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1
Q

Describe how R groups interact to determine the tertiary structure of a protein (4)

A

1 some R groups, attract / repel ;
2 disulfide, bridges / bond ;
3 between, cysteine / SH / S (atoms) ;
4 hydrogen / H, bonds ;
5 ionic bonds between, oppositely charged / + and -, R groups ;
6 hydrophilic R groups, on outside of molecule / in contact with
water (molecules) ;
7 hydrophobic R groups,
on inside of molecule / shielded from water (molecules) ;

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2
Q

What are 3 differences between the structure of glycogen and collagen? (3)

A

1 polysaccharide and protein / polypeptide ;
2 (alpha) glucose (units) amino acid (units) ;
3 identical units different amino acid units ;
4 glycosidic, bonds / links peptide, bonds / links ;
5 branched unb / linear ;
6 non-helical ;
7 one chain (per molecule) three chains (per molecule) ;
8 no cross links cross links (between
chains) ;
9 contains C H O contains C H O N ;

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3
Q

State 2 properties of collagen making it suitable for ligaments (2)

A

strong
insoluble
flexible

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4
Q

State two properties of cellulose making it suitable for cell membranes (2)

A

unreactive
insoluble
flexible
forms H bonds with neighbouring chains

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5
Q

Why may some cells not take up a stain? (1)

A

cells, dead / not respiring ;

no, (metabolic) energy /ATP, to take up stain

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6
Q

Describe the function of glycolipid in the cells surface membrance? (5)

A

1 (acting as) antigens ;
2 identification / recognition, (of cells) as, self / non-self / AW ;
3 cell signalling / described ;
4 receptor / binding site, for, hormone / (chemical) signal / (medicinal / named) drugs ;
5 ref. to receptor / binding site / trigger,on transport proteins / AW ;
6 cell adhesion / to hold cells together (in a tissue) ;
7 attach to water molecules (to stabilise membrane / cell) ;

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7
Q

What is the role of the phospholipid bilayer? (1)

A

to act as a barrier (to, polar / charged, particles) / select what enters or leaves cell ;
ACCEPT selectively permeable or partially permeable membrane
ACCEPT allows small / fat soluble molecules to pass through

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8
Q

Explain why new branches are seen growing just under the bark of the cut suface of the plant? (2)

A

This is where cambium / meristem / xylem / phloem / vascular bundle, is found ;
mitosis/cell division, occurs in cambium (to produce new cells for growth) ;
new cells, differentiate / specialise, (into xylem and phloem) ;
xylem supplies water for, (cell) elongation / (cell) growth ; phloem supplies, sugars / assimilates, for, energy / growth /respiration

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9
Q

Suggest why plants need lenticels (cells to allow gases to diffuse into living tissues of the trunk (2)

A

allow oxygen to reach, cells / tissues (under bark) ;
for (aerobic) respiration ;
animals transport oxygen in, blood / circulation / transport system ;
plants do not transport (much) oxygen in transport system ;
idea that (oxygen not supplied from leaves as) stomata only open in day / no leaves in winter ;

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10
Q

Complete this passage about the loop of Henle (6)
Electrolytes such as sodium —– are actively reabsorbed from the filtrate at the —– of the loop of Henle. This reduces the —– —– of the surrounging tissues in the —– of the kidney. The walls od the desending loop are —– to water. The result is that water is reabsorbed from the filtrate by the process of —–.

A
ions 
asending limb
water potential
medulla 
permeable 
osmosis
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11
Q

Predict the effect of a non functioning glucose transport protein on the volume of the filtrate (3)

A
  • volume increase
  • glucose lowers water potential graident
  • reduction of water potential from the filtrate and cortex
  • less water absorbed from desending limb
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12
Q

Where are podocytes located? (1)

A

Bowman’s capsule

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13
Q

How does ornithine and citrulline move into and out of the mitrochondria? (2)

A
  • AT as need to be moved more quickly than would be met by diffusion
    OR
  • Facilitated diffusion as conversion of ornithine to citrulline creates concentration graidents
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14
Q

Give one way in which a laser scanning confocal microscope differs from an electron microscope? (1)

A

LSCM has a …

  • lower resolution
  • can have a fluorescent tag
  • can see movement
  • can say different layers/depths
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15
Q

State two reasons why a cell may look in prophase? (2)

A
  • chromosomes condensed
  • chromosomes not organised
  • nuclear envelope is present
  • no nucleolus
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16
Q

Explain how the organisation of homologous chromosomes during Metaphase 1 increases genetic variation? (3)

A
  • independent assortment
  • (homologous chromosomes) line up along the centre of the cell/metaphase plate/equator
  • either chromosome could end up in either cell
  • each chromosome of the homologous pair is genetically different
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17
Q

Describe a procedure to observe the positions of xylem vessels in a leaf stalk of celery? (2)

A
  • cut a cross-section

- add a stain and observe under a microscope

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18
Q

State 1 similarity and 2 differences between the structure of the xylem and the phloem (3)

A
Similarities: 
-both made up of cells joined end to end
-both made up of more than one cell type
-xylem vessels and sieve tube elements both lack nuclei
Differences:
X lignified P no lignin
X no sieve plated P sieve plates 
X no companion cells P companion cells 
X pits P no pits
X no cytoplasm/organelles P has cytoplasm and some organelles
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19
Q

Describe how you would do a dissection of a insect gaseous exchange system? (2)

A
  • cup open exoskeleton

- observe tracheoles/ tracheae using saline solution

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20
Q

How is the trachea of a mammal different from that of an insect? (2)

A
  • Mammals have 1 trachea and insects have multiple
  • Mammals have a larger diameter
  • Mammals have cartilage but insects have chitin
  • Mammals have C - shaped cartilage and insects have spiral
  • Mammals trachea branches into bronchi while plants into tracheoles
  • Mammal trachea has smooth muscle/goblet cells and insect tracheae do not
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21
Q

Explain the differences in duration between primary and secondary infection? (2)

A

Primary is slower due to clonal selection/expansion/production of antibodies.
Secondary is quicker because of memory cells/more antibodies produced/immunological memory.

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22
Q

What do scientists need to control when doing biodiversity experiments? (1)

A
  • same time of year/day
  • same length/number of transects
  • same counting/capture technique
  • same place in habitat
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23
Q

State 3 adaptations to hydrophytes? (3)

A
  • air spaces in leaves to allow leaves to float to receive light for photosynthesis
  • stomata on upper side of leaf so they have access to C02
  • roots reduced/absent as not required to obtain water/not wasting resources
  • waxy cuticle so water does not block stomata
  • reduced vascular tissues due to high water availability
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24
Q

Explain why an electrocardiogram may not be an accurate representation of a persons heart rate? (3)

A
  • only 1 cardiac cycle shown
  • could be anonymous/atypical
  • mean of several cycles would be better
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25
Q

Explain how the structure of a phospholipid allows them to form the bilayer? (3)

A
  • hydrophilic head and hydrophobic tail
  • hydrophobic tail repelled by water
  • hydrophilic head forms H bonds with water
  • medium outside plasma membrane in aqueous
  • hydrophobic nature of tail results in their facing towards each other
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26
Q

Suggest what roles these ions have in helping cut plants last longer? (2)
H+
Na+

A
H+ = maintain/regulate pH
Na+ = regulate water potential
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27
Q

What causes the fluctuation of pressure in the aorta? (2)

A
  • systole increases pressure
  • diastole decreases pressure
  • systole is ventricular
  • left ventricle
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28
Q

Why does pressure have to decrease from the aorta to the capillaries? (2)

A
  • capillary (wall) is, thin / only one cell thick ;
  • (high pressure would) burst / damage, capillary (wall) ;
  • reduce chance of, tissue fluid build up / oedema
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29
Q

Describe and explain how the wall of an artery is adapted both to withstand and maintain
high hydrostatic pressure (5)

A
To withstand pressure:
wall is thick ;
(thick layer of) collagen ;
(wall / collagen) provides strength ;
endothelium, corrugated / folded ;
idea of: no damage to, endothelium / artery (wall) (as it
stretches) ;
max 3

To maintain pressure:
(thick layer of) elastic tissue / elastic fibres / elastin ;
to cause recoil / return to original size ;
(thick layer of) smooth muscle ;
narrows / constricts, lumen / artery ;

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30
Q

How can you tell the distance between the strands in DNA is not always the same? (1)

A

DNA creates a double helix shape which would not occur if the strands are the same length.

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31
Q

How does carrying out replicates improve an investigation? (2)

A
  • calculate a mean
  • anomalies can be identified
  • improves repeatability
  • allows statistical tests to be completed
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32
Q

Explain how paralysis of the diaphragm could lead to suffocation? (2)

A
  • no/little increase in volume of thorax
  • no/little decrease in pressure in the thorax
  • less air drawn into lungs
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33
Q

What effect will reducing the speed of conduction of Purkyne fibres have on heart rate? (3)

A
  • slows/decreases heart rate
  • slows transmission of impulse from AVN to ventricles
  • slows ventricular systole
  • longer delay before ventricular systole begins
  • increases time the heart is in diastole
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34
Q

Explain why the wall of the left ventricle is thicker than the wall of the left atrium? (3)

A
1 (more muscle to create) more force ;
2 (needs to create) higher pressure ;
3 push blood against greater , resistance / friction ;
4 (left ventricle) pumps blood further /
pumps blood to all parts of body /
supplies systemic circulation ;
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35
Q

Explain why the curve for fetal oxyhaemoglobin is to the left of the curve for adult oxyhaemoglobin? (4)

A

1 fetal haemoglobin has a higher affinity (for
oxygen) ( than adult haemoglobin) ;
2 (fetal Hb) takes up oxygen in low(er) partial
pressure of oxygen ;
3 placenta has low partial pressure of oxygen ;
4 at low partial pressure of oxygen / in placenta,
adult (oxy)haemoglobin will dissociate / AW ;

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36
Q

Suggest the effects of kidney failure on the composition of the blood (2)

A
  • higher conc of urea
  • higher conc of ions/salts
  • increase in water
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37
Q

Explain the need for close matching of a donated kidney to a recipient (3)

A

Donated kidney will be recognised as foreign/non self
Antigens on donated kidney will be different
Causing rejection
By immune system

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38
Q

Explain the ways in which the Bowmans capsule and the Glomerulus are adapted (5)

A

Ultrafiltration
Afferent arteriole is wider than efferent arteriole
High hydrostatic pressure in glomerulus
Endothelium has gaps to allow passage of substances
Basement membrane stops removal of large molecules
Podocytes have projections
Projections ensure gaps to allow passage

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39
Q

ADH is a hormone which is produced by specialised nerve cells known as —- cells.
These cells detect changes in the water potential of the blood flowing through the —-. If the water potential of the blood is too low ADH is released. ADH s not secreted immediately into the blood but passes along the —- of the specialised nerve cells to the —- gland where it is released. ADH acts on the cells of the —-. The ADH molecule attaches to the —- of these cells. (6)

A
Osmoreceptor 
Hypothalamus 
Axon
Posterior pituitary 
Collecting duct 
Cell membrane
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40
Q

ADH is a hormone. Suggest where it is removed in the blood describing what happens to the ADH molecule (3)

A
Liver cells 
Hydrolysis of protein 
Deamination occurs
Ornithine cycle 
Amino acid used in metabolic pathway 
Ultrafiltration from blood 
Urea present in urine 
Excreted
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41
Q

State two processes which occur in a cell during interphase (2)

A
  • ATP content of cell increased
  • Cell growth
  • Protein Synthesis
  • Checking genetic material
  • Increase in the number of organelles
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42
Q

Who is cell division in a plant different to that in an animal? (2)

A

Plant:

  • plate/wall forms
  • cytokinesis starts from middle of cell
  • occurs in meristems
  • no centrioles
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43
Q

What does meristematic tissue need to be stained for investigating the number of cells in each phase (2)

A
  • to be able to see the individual chromosomes
  • to provide a contrast between cell structures
  • to determine the different stages of mitosis
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44
Q

Before division of the nucleus of the cell, the frantic material must replicate in mitosis. State why (2)

A
  • both cells are genetically identical to mother

- both cells receive a diploid number of chromosomes

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45
Q

Describe how cells in a multicellular organisms are organised (5)

A
  • cells are differentiated/specialised
  • cells form tissue
  • tissues form organs
  • a group of organs form organ systems
  • cells/tissues/organs/organ systems work together
  • named example of tissue/organ/organ system
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46
Q

How might the peritoneum differ in its function from the artificial membrane in a dialysis
machine used in haemodialysis? (1)

A

it can perform , active transport / facilitated diffusion

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47
Q

Why does the dialysis fluid used in peritoneal dialysis contain dextrose solution rather
than water alone? (2)

A

1 idea that (dialysis is replicating function of kidney and)
part of kidney’s function is to remove
(excess) water from blood ;
2 (dextrose / sugar) reduces , water potential / 
(of dialysis fluid)
or
(dextrose / sugar , solution)
has a lower , water potential /  (than water) ;
3 water moves from blood (into dialysis fluid)
by osmosis
or
prevents water moving into the blood
(from dialysis fluid) by osmosis ;
4 (if it was water alone) cells would , swell / burst ;

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48
Q

Suggest why patients receiving peritoneal dialysis usually need to have the peritoneal
dialysis fluid replaced four times a day, but those receiving haemodialysis only need
treatment three times a week (2)

A

1 peritoneal dialysis can remove
less (named) waste
(than haemodialysis) ;
2 idea that
in haemodialysis dialysis fluid is constantly ,
refreshed / changed
(but not in peritoneal dialysis) ;
3
4
haemodialysis uses counter-current flow ;
idea that
haemodialysis maintains concentration gradient
or
in peritoneal dialysis the concentration gradient ,
reduces / is lower ;
5 (in peritoneal dialysis) the fluid reaches equilibrium
with the blood ;

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49
Q

The blood in the glomerulus has a high ………………………………………………. pressure,
which forces small molecules, such as glucose and …………………………………………….. ,
out of the glomerulus and into the lumen of the Bowman’s capsule. This process is
known as ……………………………………………… .
In the proximal convoluted tubule, the glucose, most of the ……………………………………….. and
some of the salts are reabsorbed into blood ………………………………………………. that surround
the nephron at this point.

A
hydrostatic ;
water / urea / amino acids / vitamins / small proteins ;
ultrafiltration ;
water ;
capillaries / vessels ;
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50
Q

Suggest and explain what effect the action of aldosterone will have on the secretion of
ADH (2)

A

-water potential of , plasma / blood , will ,
decrease / become more negative ;
-(ADH secretion) will increase ;

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51
Q

Which part(s) of the nephron corresponds to each of the statements in the table below?

walls are impermeable to water
glucose is reabsorbed into the blood
ADH acts on the walls
contains podocytes
most of the water is reabsorbed into the blood
A
ascending loop of Henle 
proximal convoluted tubule 
collecting duct
Bowman's capsule
Proximal convoluted tubule
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52
Q

State the effect that the environment has on discontinuous and continuous variation (2)

A

of
1 no / little , environmental effect for ,
(named example of) discontinuous variation /
example given for discontinuous variation in (i) as ecf ;
2 some / large , environmental effect for ,
(named example of) continuous variation /
example given for continuous variation in (i) as ecf ;

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53
Q

State one advantage and one disadvantage of using clones to test a treatment for a disease (2)

A
advantage
(genetically identical so) all react the same
or
genetic variable controlled ;
disadvantage
expensive (to produce)
or
don’t see varied response to drug like in real populations
(of mice)
or
idea that clones (of mice) may have unknown health issue
(which would affect responses) ;
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54
Q

What is meant by homozygous and gene locus? (2)

A

(individual / cat / genotype with) 2 identical,
alleles / version of the gene / forms of the gene ;
gene locus
position / place / location, of, gene / allele, on chromosome

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55
Q

Suggest why physiological problems in pedigree animals are more common than wild animals (2)

A

1 inbreeding / small or decreasing, gene pool ;
2 homozygous recessive (genotypes) ;
3 gene / allele , for desired characteristic on same
chromosome as problem, gene / allele ;
4 selecting for one trait (unintentionally) selects for another ;
5 breeders select for looks not health ;
6 weaker selection against less healthy animals (than in wild) ;

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56
Q

Which ions along the axon are at higher concentrations in the extra cellular compared to the intracellular space? (1)

A

Na+ and Cl-

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57
Q

Which is the following brain regions is responsible for controlling balance? (1)

  • hypothalamus
  • medulla oblongata
  • cerebellum
  • temporal lobe
A

Cerebellum

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58
Q

Where precisely in the body is adrenaline produced? (1)

A

Adrenal Medulla

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59
Q

Are these insitu or exsitu forms of conservation? (1)

  • seed bank
  • botanic gardens
  • SSSI forest
  • marine reserve
A

Exsitu
Exsitu
Insitu
Insitu

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60
Q

Which of these is the specific location that light dependent reactions take place? (1)

1) chloroplast
2) thylakoid membrane
3) stroma
4) lumen of the grana

A

2

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61
Q
By what mechanism is a rare disease found at high frequencies?(1)
A) genetic bottleneck 
B) mutation 
C) artificial selection 
D) founder effect
A

D

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62
Q
On a typical growth curve, what stage would penicillin be produced by the bacteria?(1)
A) lag phase 
B) log phase 
C) stationary phase 
D) death phase
A

C

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63
Q

Which part of the lac operon codes for the transcription factor? (1)

A

The regulatory Gene

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64
Q

Why is it vital to give someone a booster dose of the same vaccine? (1)

A

The memory cells have undergone apoptosis

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65
Q

Outline the reasons why insects and other animals need well-developed transport systems (3)

A

high metabolic , demands / rate 
need , large oxygen / rapid oxygen , supply 
diffusion , not sufficient / too slow / distance too far 
(to) maintain , steep / AW , concentration / diffusion , gradient(s) 
surface area to volume ratio is (usually) low 
(named) metabolite(s) needed by cells / (named) waste(s) removed from cells 

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66
Q

How do you know a TEM microscope has been used? (2)

A
2D image 
internal details visible 
(named) organelles / ultrastructures , visible 
high magnification 
high resolution 
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67
Q

Explain why a plant leaf is described as an organ (4)

A

organ is
collection / AW , of tissues 
perform / carry out / adapted to , function / role 
leaves have
two from: epidermis / spongy mesophyll / palisade mesophyll / vascular / phloem / xylem , (tissues) 
(to carry out) photosynthesis / gaseous exchange 

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68
Q

What can large standard deviations show on a graph? (1)

A

That a random error has occured

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69
Q

Explain why podocytes are usually unable to undergo mitosis (3)

A

have already / are , differentiated / specialised
(so cannot divide) 
2 are in , G0 (phase of cell cycle) / resting phase 
3 idea that shape is (too) , irregular / asymmetrical
(so cannot divide) 
4 cytoskeleton cannot function / spindle (fibres)
cannot form
5 (if mitosis occurred) it would alter , number / size ,
of the , gaps / fenestrations 
6 idea that it would alter an aspect of ultrafiltration

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70
Q

Explain why the toxins produced by the different strains are described as immunologically distinct and how they are dealt with by the immune system (6)`

A

1) toxins produced by each strain will be slightly different
2) each toxin with have a different 3D shape
3) toxin acts as an antigen
4) immune response determined by the shape of antigen
5) APC inject antigen and display antigens on surface
6) interaction causes production of interleukins
7) B cells activated by T-Helper cells
8) Clonal selection and clonal expansion
9) B cells differentiate into plasma cells
10) plasma cells produce antibodies
11) by protein synthesis antibodies bind to and neutralise toxins

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71
Q

What is meant by an autoimmune disease? (2)

A

An abnormal immune response

Against tissues normally in the body

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72
Q

Suggest why antibodies specific to nuclear proteins are not normally made (1)

A

They are usually hidden in the nucleus

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73
Q

Name two different types of T lymphocytes and describe their role in the immune system (2)

A
  • Helper cells which produce interleukins
  • Killer cells secrete perforin to kill cells
  • Memory cells for a faster/secondary immune response
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74
Q

State two possible sources of natural medicines (2)

A

plants and microorganisms

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75
Q

Outline the processes that lead to the production of antibodies against an unfamiliar bacterium (3)

A
  • B cells/lymphocytes carry an antibody on surface/complementary to one antigen
  • Selected/activated B cell clones/divides by mitosis
  • forms/differentiates into plasma/effector cells
  • which secretes antibodies/complementary to antigen
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76
Q

Explain how helper T cells act to speed up B cell stimulation? (2)

A

T Helper cells are stimulated by antigen-presenting cells.
Release cytokines/interleukins.
Stimulate B cells/mitosis/clonal expansion

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77
Q

Explain why vaccinations are an example of active immunity (2)

A

Antibodies produced
Activation of lymphocytes of person being vaccinated
Memory cells remain

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78
Q

Explain why vaccinations are an example of active immunity (2)

A
  • Different pathogens have different antigens
  • Antigens have a specific shape
  • Shape of antibody must be complementary to a specific antigen
  • Different antibody needed for each pathogen
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79
Q

Describe the actions of the B lymphocytes in the immune response (8)

A
  • Humoral response
  • B cells have antigen receptor/carries antibody on its surface
  • Matches to one antigen
  • Clonal selection
  • Selection of B lymphocyte
  • by macrophages/ APC / T helper cells / interleukins
  • Clonal expansion
  • Cells divide by mitosis/clones
  • Differentiate/specialise
  • B cells form plasma/effector cells
  • Secrete/produce antibodies
  • Antibodies are specific/complementary to an antigen
  • B cells form memory cells
  • Secondary response
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80
Q

Explain why the response to the subsequent infection is much bigger than the response to vaccination? (3)

A

Clonal selection
Clonal Expansion
Differenciation

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81
Q

Describe two ways in which the structure of part C is adapted to its function (2)

A

1 contain , (named) pigment (molecules) /
photosystems ;
2 contain ,
(named) electron carriers / ETC / ATP synth(et)ase ;
3 idea that has a large surface area (in a small volume)
for , light absorption /
light dependent reaction(s) /
light dependent stage /
electron transport ;

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82
Q

With reference to the biochemistry of photosynthesis, explain why the theoretical rate of photosynthesis is not achieved at higher light intensities (2)

A

1 at high light intensity
other (named) factor becomes a limiting factor ;
2 idea that temperature becomes limiting as ,
Calvin cycle / light independent reaction ,
involves enzymes /
relies on kinetic energy of molecules ;
3 idea that CO2 (concentration) becomes limiting as it is
required for ,
Calvin cycle / light independent reaction /
formation of (named) Calvin cycle compound /
reaction with RuBP / fixation by Rubisco ;

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83
Q

Suggest one way in which the structure of a leaf in shaded area will differ (1)

A

shade leaf will have
1
2
3
large(r) / more , chloroplast(s) / (palisade) mesophyll ;
more , grana / thylakoids (in chloroplast) ;
large(r) surface area (of leaves) ;

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84
Q

State the advantage to the plant of having a range of accessory pigments in photosystems (1)

A

able to , absorb / use ,
a range of / different / more / other ,
(light) wavelengths / ;

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85
Q

Name the products of the light-dependent of photosynthesis (3)

A

reduced NADP / NADPH / NADPH2 / NADPH+ ;
ATP ;
oxygen ;

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86
Q

What stage of the DNA cycle does DNA Replication occur? (1)

A

The synthesis phase of interphase

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87
Q

What are the products of DNA replication compared to transcription? (1)

A

DNA replication produces two double stranded DNA molecules and transcription produces one mRNA molecule

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88
Q

What does a stop codon do to stop the formation of the polypeptide? (1)

A

A stop codon does not bring down any amino acids so the polypeptide chain stops

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89
Q

Choose three words which are wrong and replace them (3)
Replication takes place in the S-phase of mitosis.
The DNA molecules unwinds.
Free DNA nucleotides are activated.
Thymine pairs with adenosine.
The nucleotides are joined by DNA helicase.
Cytosine pairs with guanine.

A

Mitosis - Interphase
Adenosine - Adenine
DNA helicase - DNA polymerase

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90
Q

Outline the processes which occur in G1 and G2 (4)

A

G1 (2 marks maximum)(more) protein, synthesised / made;(more) cytoplasm volume increases;cell, grows / increases in size;(more) organelles, produced / grow anddivide / replicate;
G2(more) organelles, produced / grow anddivide / replicate;energy stores, increase / AW;idea of (DNA) proofreading / checkpoin

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91
Q

Outline the processes and organelles involved in the translation of these proteins from RNA (4)

A

(m)RNA transported out of nucleus (1)(m)RNA transported to / associates withribosome (1)translation / protein synthesis, occurs atribosome (1)(t)RNA brings specific amino acids or(t)RNA described (1)peptide bonds form between adjacentamino acids or peptide bonds described (1)polypeptide / protein processed through Golgi apparatus (1)

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92
Q

Describe how gene expression can be regulated after transcription (3)

A

primary mRNA is modified (1)removal of introns to produce maturemRNA (1)Alternative splicing can produce differentversions of mRNA (1)protein must be activated by cAMP /phosphorylation (1)binding (of cAMP) alters shape of protein

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93
Q

Explain why the rate of photosynthesis decreased at temperatures above 25 degrees (4)

A

1 denaturing of enzyme; 2 change in shape of active site; 3 named photosynthetic enzyme; 4 less photolysis; 5 less ATP produced; 6 named step in Calvin cycle which is affected; A step described

7 increase in rate of respiration; 8 respiration occurring at faster rate than photosynthesis; 9 temperature compensation point;

10 increased rate of transpiration; 11 stomatal closure; 12 less carbon dioxide uptake;

13 AVP; e.g. ref to photorespiration

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94
Q

Explain why CO2 was released when CO2 concentrations were low for the plant (2)

A

ref respiration;

production of carbon dioxide; R release

(at low concentrations, CO2 was) diffusing / moving down a concentration gradient;

respiration faster than photosynthesis / AW;

AVP; e.g. below compensation point

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95
Q

Suggest why it was important that the leaves remained attached to the plants while the measurement were made in photosynthesis? (2)

A

maintenance of water supply;

xylem / vascular bundles, intact;

water required for, photosynthesis / turgor; A water prevents wilting

stomata might close if the leaf detached;

leaves site of photosynthesis;

AVP; e.g. ABA, water stress, sugar transport

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96
Q

Outline the ways in which heterotrophic organisms are dependant on plants (3)

A
1 animals / heterotrophs (need to) ,
eat / obtain organic material from / AW ,
plants / autotrophs ;
2 (plants / autotrophs) produce
(named) organic molecules during ,
photosynthesis / Calvin cycle /
light independent stage ;
3 (plants / autotrophs) produce oxygen during ,
photosynthesis / photolysis /
light dependent stage;
4 glucose / carbohydrate / oxygen ,
(produced in photosynthesis)
are used in respiration by ,
animals / heterotrophs
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97
Q

Name two polysaccharides that can be synthesised from the end products of the light independent stage of photosynthesis (2)

A

starch / amylose / amylopectin
and
cellulose ;

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98
Q

Define what is meant by autotroph and heterotroph (2)

A

autotroph
can make ,
organic molecule(s) / named organic molecule(s) ,
from , inorganic molecule(s) / carbon dioxide ;
heterotroph
relies on / needs to use / has to obtain /
feeds on and digests ,
(named) organic molecules (that have been made
by another organism) ;

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99
Q

Explain what fat droplets in the chloroplast might be used for (1)

A

for membrane formation
or
phospholipid / cholesterol / glycolipid , for membrane ;
fatty acid / (named) pigment , synthesis

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100
Q

Suggest the effect of the herbicide binding to the electron carriers will have on photosynthesis (2)

A

1 prevents non-cyclic photophosphorylation ;
2 no electron(s) available to form reduced NADP ;
3 idea that ATP production by cyclic
photophosphorylation is not prevented ;
4 no / less , ATP and no reduced NADP available for ,
Calvin cycle / light independent reaction /
conversion of GP to TP ;

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101
Q

Describe why measuring carbon dioxide and oxygen production may both not be accurate (2)

A
1
2
3
4
5
oxygen
oxygen only produced in one (named) stage of
photosynthesis ;
oxygen produced might be used for respiration ;
carbon dioxide
CO2 only used in one (named) stage of photosynthesis ;
CO2 produced during respiration might be used for ,
photosynthesis /
light independent reaction /
Calvin cycle ;
O2 / CO2 / both , could be an underestimate
or
represents net production (O2)
or
represents net use (CO2) ;
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102
Q

Paraquat binds to electrons in photosystem 1. Suggest how in results in death of the plant (2)

A
1 prevents photophosphorylation ;
2 cyclic and non-cyclic ;
3 no / less , ATP / reduced NADP , for ,
light-independent stage / Calvin cycle /
GP to TP ;
4 no (named) substrate made for respiration ;
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103
Q

Suggest the role of DNA and ribosomes in the chloroplast(2)

A

1 (DNA) coding for , gene(s) / protein / enzyme
or
(ribosome) protein / enzyme , synthesis ;
2 (enzymes for production of / proteins for)
chlorophyll synthesis / pigment synthesis /
photosystem ;
3 (protein for) electron , acceptor(s) / carrier(s) ;
4 ATP synth(et)ase ;
5 (enzyme / PSII) for , photolysis / splitting of water ;
6 (enzymes for)
Calvin cycle / light independent reaction ;

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104
Q

Suggest why not all the oxygen produced by the plant in photosynthesis is collected (2)

A

1 would dissolve in the water ;
2 used in , respiration / oxidative phosphorylation ;
3 may escape the collection apparatus ;
4 trapped in , a bubble attached to / air spaces in ,
the leaf

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105
Q

Why might nitrogen be collected from a plant in a photosynthesis reaction? (1)

A

1 (nitrogen) was present in the air (spaces) in the ,
leaf / plant ;
2 (nitrogen) leaves the plant with the oxygen ;
3 idea that (nitrogen) comes out of solution /
‘undissolved’ (as less soluble in warm water) ;

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106
Q

Suggest the advantage of plants deep in water to having different accessory pigments (2)

A

intensity
1 in deeper water there is , less / lower , light intensity ;
2 (these pigments) can absorb what (little) light there is ;
wavelength
3 not all wavelengths of light can penetrate
or
mainly shorter wavelengths can penetrate
or
(mostly) blue light (450 – 520 nm) penetrates ;
4 (these pigments) can absorb
wavelengths of light that can penetrate
(deeper water) ;

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107
Q

Discuss the fate of TP in the Calvin Cycle (3)

A

1 regenerates / produces , ribulose bisphosphate / RuBP ;
2 so cycle can continue / for (further) CO2 fixation /
to combine with CO2 ;
3 formation of (named) , sugar / glucose / hexose / sucrose /
starch / cellulose ;
4 formation of (named) ,
fat / triglyceride / lipid / fatty acids / glycerol /
amino acids / protein /
nucleic acids / nucleotides ;
5 10x TP for RuBP and 2x TP for production
or
most TP used to produce RuBP and the rest for production

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108
Q

Explain why the Bohr effect occurs (2)

A
  • reduces affinity for oxygen
  • formation of haemoglobinic acid
  • prevents a fall in pH
  • alters shape of haemoglobin
  • more 02 released where CO2 concentration is high
  • Co2 binds to haemoglobin forming haemoglobinic acid
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109
Q

Describe the role of haemoglobin in transporting oxygen around the body (2)

A

1 haemoglobin has a high affinity for oxygen
2 oxygen binds to haemoglobin in high partial pressures
3 oxyhaemoglobin
4 oxygen released where oxygen partial pressure is low

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110
Q

Explain how selective breeding that led to this increased yield could have been done? (4)

A
  • breed high yielding plants together
  • access/test yield
  • crossbreed best offspring
  • over many generations
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111
Q

Define the term recombinant DNA (1)

A

DNA which has been combined from two sources

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112
Q

State what is meant by biotechnology using examples and suggest the advantages of using microorganisms for this (6)

A
  • large-scale / industrial / commercial use (of living
    organisms / enzymes) ;
  • to produce , food / named example ;
  • detail of , microbe / enzyme , involved ;
  • to produce , drugs / named example ;
  • detail of , microbe / enzyme , involved ;
    to make , (useful) enzymes / biogas / calcium citrate /
  • for bioremediation / for water treatment / for microbial
    mining ;
    Advantages of microorganisms
  • fast, growth / reproduction / products ;
  • microbes can be genetically engineered ;
  • processes occur at low , temperatures / pressures ;
  • low , temp / pressure , cheaper / safer , to maintain ;
  • products , pure / easy to separate ;
  • grow on unwanted, food / nutrients ;
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113
Q

What is graphical evidence that a substance is a secondary metabolite? (2)

A
  • it is produced after main growth cycle

- it is not needed for growth

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114
Q

What is the importance of maintaining aseptic technique in fermentation? (3)

A

to avoid unwanted microbe , entry / presence ;
so no competition for nutrients ;
so conditions remain unchanged ;
so no decrease in yield ;
so no contamination of , batch / product / penicillin
or
batch is unusable ;
to prevent escape of ,
microbes / fungus / Penicillium / spores ;

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115
Q

State 3 physical factors in a fermenter that need to be monitored and controlled and why (3)

A

pH - enzyme activity
temp - enzyme activity
oxygen concentration - respiration levels

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116
Q

Give 2 advantages of immobilised enzymes (2)

A

(enzyme can be removed to be) used again ;
(enzyme can) to leave pure(r) product ; ora
(enzyme) more stable / more efficient / works better ;

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117
Q

Outline the process by which bacteria can be genetically modified (6)

A
Section I - Obtaining the gene
use restriction, enzyme / endonuclease ;
to, cut out / get / isolate, (rennin) gene / DNA coding for rennin
or to, fragment / digest, DNA ;
gene probe ;
OR
obtain rennin mRNA ;
(use) reverse transcriptase ;
to make cDNA ;
OR
sequence, rennin (protein) ;
work out base code ;
make this DNA sequence ;
sticky ends ;
Section II - Vector
cut (open), plasmid / phage ;
using same restriction enzyme ;
annealing / base pairing of sticky ends ;
join sugar-phosphate backbones ;
(using DNA) ligase ;
recombinant, vector / plasmid / phage / DNA ;
Section III - Introduction into host cell
mix with bacteria ;
detail of conditions ;
transformation (plasmid) / transduction (phage) ;
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118
Q

Discuss the benefits of using immobilised enzymes for large scale production (4)

A

(enzyme) can be re-used so reduces cost ;
product, pure(r) / uncontaminated ;
reduced downstream processing costs ;
(immobilised enzyme) works at high(er) temperature ;
(immobilised enzyme) works in changed pH ;
reaction, can be faster / have higher yield ,
because can be done at higher temperature ;

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119
Q

Define the term recombinant DNA (1)

A

DNA (combined) from (two) , sources / organisms ;

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120
Q

Outline the process of somatic cell therapy (5)

A

somatic / adult, cell / nucleus ;
fused with / injected into ;
empty / enucleate , egg cell ;
from another goat ;
idea of electric shock / electrostimulation ;
this cell or embryo, grown on , in vitro / in tied oviduct ;
(early) embryo / blastocyst , split ;
idea that embryos replaced in , surrogate mothers

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121
Q

Outline the process of glycolysis (4)

A

1 phosphorylation of glucose ;
2 so forming hexose (1,6) bisphosphate ;
3 (then) splitting into / formation of ,
two / 2 , triose phosphate(s) / TP ;
4 (for formation of pyruvate) dehydrogenation /
oxidation / formation of reduced NAD ;
5 yruvate produced (from , TP / (3C) intermediate) ;
6 total production 4 ATP / net production of 2 ATP ;

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122
Q

Explain what might happen to a person if the liver did not break down insulin (2)

A

1 blood glucose (concentration) would fall ,
too low / below normal level ;
2 idea that
glucose would continue to be taken up by ,
cells / liver / muscle (results in low blood glucose)
or
idea that
glucose is continually converted into glycogen /
would store too much glucose as glycogen ;
3 (mitochondria eventually) cannot ,
release enough energy / generate enough ATP
(as less available glucose in blood) ;
4 coma / death ;

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123
Q

When mitochondria are extracted from cells, they are usually kept in a 0.25 mol dm-3 sucrose solution.
What is the purpose of the sucrose solution?
A it is used as a solvent
B it maintains a constant pH by acting as a buffer
C it acts as a source of food for respiration
D it prevents the mitochondria from changing structure

A

D

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124
Q

Which of the following is absent from prokaryotic cells?

A plasmids
B cell wall
C rough endoplasmic reticulum
D ribosomes

A

C

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125
Q
On complete hydrolysis, which of the following would produce the fewest molecules?
A	phospholipid	
B	triglyceride	
C	sucrose	
D polypeptide
A

C (only 2 molecules produced) - 1 fructose and 1 glucose

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126
Q
Which of the following molecules does not yield only α glucose molecules on complete hydrolysis?
A	amylose	
B	glycogen	
C	maltose	
D     sucrose
A

D (produces fructose also)

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127
Q

Analysis of a sample of DNA found that 20% of the bases were adenine.

What percentage of the bases would be pyrimidines? 
A 20% 
B 30% 
C 60% 
D 50%
A

D
20% thymine
30% cytosine

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128
Q
What is the approximate temperature coefficient (Q10) of an enzyme-controlled reaction?
A	50	
B	10	
C	2	
D     1
A

C - the rate of the reaction doubles with temperature going up by ten degrees

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129
Q
When an enzyme is subjected to temperatures above the optimum, it denatures. Which of the following bonds are the first to be disrupted by high temperatures?
A	disulfide	
B	hydrogen	
C	ionic	
D     peptide
A

B

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130
Q

Why do we store glycogen and not glucose? (3)

A
  • insoluble so no affect on water potential
  • metabolically inactive
  • compact so lots can be stored in a small place
  • able to store lots of energy
  • has lots of ends to be broken down and release glucose quickly
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131
Q

Why can progesterone move through the phospholipid bilayer? (2)

A
  • non polar/ lipid/ hydrophobic/ fat soluble

- it can diffuse through the phospholipid bilayer

132
Q

Explain why more is absorbed from a colorimeter when temperature increases with beetroot (5)

A
  • increase in pigment causes an increase in absorption
  • low temperatures there is little change in absorption
  • the membrane is undamaged
  • at higher temperatures there’s a higher increase in pigment
  • this then leaks out when the membrane gets more damaged / becomes more permeable / move further apart
133
Q

What is the point of DNA polymerase? (1)

A

Forming phosphodiester bonds between molecules

134
Q

What is one thing that needs to be done before a plant cross section can be observed? (1)

A

A stain needs to be added

135
Q

Why can expiration be a passive process? (1)

A

it does not use muscle contraction / muscles (just) relax
or
rib cage , falls / drops (due to gravity)
or
lungs (elastic so) will recoil 

136
Q

Given chitin is made from beta glucose, describe the formation of a polysaccharide (4)

A

1 (in chitin glycosidic bond(s) formed by) condensation 
2 (molecule of) H2O / water , produced / released 
3 alternate monomers are , upside-down / flipped / rotated through 180o 
4 because of the position of the , OH / H , on carbon 1 
5 forms a , straight / linear / unbranched , chain / molecule / polymer 
6 similar to cellulose 

137
Q

Why might a white spotting tile be used instead of just adding a load of indicator? (1)

A
(looking at , a small volume / against a white background) makes it easier to see the colour change 
the indicator (if added to test tube) might affect the progress of the enzyme reaction 
better temperature control as test tube not taken in and out of water bath 
138
Q

State the structures and functions and the 3 types of muscle (6)

A

Function:

  • cardiac is for the pumping of blood
  • smooth muscle for the control of the bronchioles and blood vessels
  • skeletal for the movement of muscle and bones

Structure:

  • cardiac is uni nucleated and some striations
  • smooth is uni nucleated and spindle shaped and not striated
  • skeletal is multi nucleated and striated
139
Q

Suggest why individuals have 2 allies specifically(2)

A
  • humans have diploid cells
  • chromosomes are in pairs
  • one allele on each chromosome from parent
140
Q

Give two industrial uses of plant hormones (2)

A
  • seedless fruits
  • weed killers
  • rooting powder
  • control fruit ripening
  • preserve cut flowers
141
Q

What properties of the mitochondrial inner membrane allows chemiosmosis to occur? (2)

A

Large surface area
Presence of ATP synthase
Impermeable to hydrogen ions

142
Q

State two quantitative changed which occur in the inner mitochondrial membrane which occur as a result of oxidative phophorylation (2)

A

Decrease in pH

Becomes positively charged

143
Q

What are the net products of one cycle of Krebs? (1)

A

3 NADP
2 CO2
1 ATP
1 FADH2

144
Q

Summarise the importance of coenzymes in respiration (6)

A

Coenzyme A:
- transfers acetate from Links to Krebs cycle
ATP:
- phophorylation of glucose to heroes bisphosphate
- removal of phosphate group from TP in glycolysis
- dephosphoylation in the Krebs cycle
- formation from substrate level phosphorylation
- formation from oxidative phosphorylation
NAD:
- oxidises TP in glycolysis
- oxidises pyruvate in Links reaction
- oxidises intermediates in Krebs
- addition of electrons to electron transport chain
FAD:
- oxidation of intermediates in Krebs

145
Q

Explain the difference from ATP made in Krebs and by ATP synthase (2)

A

Krebs = substrate level phosphorylation

ATP synthase = oxidative phosphorylation

146
Q

Why does aerobic respiration yield less ATP than expected? (2)

A
  1. some ATP needed to actively transport pyruvate into the mitochondria
  2. Some ATP used to transport NADH made from glycolysis
  3. Some energy released in electron transport chain is to used to transport protons
  4. Not all proton movement generates ATP
147
Q

Explain why having a large number of proton pores in the inner mitochondrial membrane will result in someone being less likely to gain weight (4)

A
  • protons leak back into matrix
  • reduces yield of ATP from chemiosmatic gradients
  • less ATP is made from oxidative phosphorylation
  • more energy wasted as heat
  • energy yield per glucose molecule decreases to n aerobic respiration
  • food not converted to ATP as efficiently
  • less energy in take in diet
  • less deposition of fat
  • fat stores may be respire for energy
148
Q

If two sucrose solutions of different concentrations are separated by a partially permeable membrane, which one of the following will occur?
A The solute will diffuse from the more concentrated to the less concentrated solution.
B Both solute and solvent will diffuse until equilibrium is reached.
C The volume of the less concentrated solution will increase.
D The volume of the less concentrated solution will decrease.

A

D

149
Q

1 There are 40 units of DNA in the cell during stage G2.
How many units of DNA are in the cell during G1?
A 10
B 20
C 40
D 80

A

B

150
Q

11 A diploid cell contains three pairs of homologous chromosomes. Each pair is heterozygous for a pair of alleles, Aa, Bb and Cc respectively.
If this diploid cell undergoes meiosis, how many different combinations of these genes could be produced in the haploid daughter cells?
A 6
B 8
C 16
D 64

A

B

151
Q

What volume cannot be measured by a spirometer? (1)

A

Residual volume

152
Q

How does surfactant stop the lungs collapsing? (1)

A

By reducing the surface tension

153
Q

Where is the heartbeat initiated? (1)

A

In the right atrium (where is SAN is)

154
Q

Which of the following statements he molecules produced during the phosphorylation stage of glycolysis? (1)
1 two molecules of triode phosphate
2 two molecules of ATP
3 two molecules of NADHZ

A

1

155
Q

What is the equation for respiratory quotient?

A

Volume of carbon dioxide produced divided by volume of oxygen produced

156
Q

Explain how acetyl coenzyme A is formed from pyruvate (4)

A

Pyruvate is decarboxylated forming one molecule of carbon dioxide.
One molecule of NAD is reduced to NADH.
Pyruvate is dehydrogenated.
This forms acetate.
Acetate combines with coenzyme A to form acetyl coenzyme A

157
Q

Explain how glycolysis can be maintained during anaerobic respiration (3)

A
  • during aerobic respiration, pyruvate is hydrogenated to lactate using NADH
  • this regenerates NAD
  • this can be used again in glycolysis to oxidise triose phosphate
158
Q

Explain how the movement of electrons down electron transport chain leads to the formation of ATP (3)

A
  • electrons pass down the chain releasing energy
  • this energy is used to pump protons from the mitochondrial membrane into the intermembrane space
  • protons then move down the electrochemical gradient via ATP synthase
159
Q

Explain what the light energy absorbed by the photosystems in photosynthesis is used for (3)

A

To make ATP from ADP
To make NADH from NAD
To split water into protons and electrons in photolysis

160
Q

Explain why using a standard deviation is better than a range (2)

A

Standard deviation takes all data into account

SD is not affected by outliers

161
Q

State where the reduced NAD and reduced FAD molecules are reoxidised and describe what happens to the hydrogen atoms (4)

A

1 inner mitochondrial membrane/cristae; 2 ref to (NADH) dehydrogenase; 3 hydrogen split into protons and electrons; 4 ref to, electron carriers/ETC/cytochromes; 5 energy released from electrons; 6 ref to protons pumped across membrane; 7 protons accumulate in intermembranal space; 8 proton gradient/pH gradient/H+ gradient; 9 protons pass through ATPase; A ATPsynthase/ ATP synthetase/stalked particle 10 ref. to oxygen (final) hydrogen/electron acceptor; 11 formation of water;

162
Q

Explain why the incomplete breakdown of glucose in anaerobic respiration produces less ATP than aerobic respiration (4)

A

1 glycolysis / conversion of glucose into pyruvate ,
occurs ;
2 produces 2 molecules of ATP (net) ;
3 (only) substrate level phosphorylation (occurs) ;
4 oxygen not available as final electron acceptor ;
pyruvate / ethanal ,
5 used to regenerate NAD for glycolysis (to continue) ;
6 (Krebs cycle and)
electron transport chain / chemiosmosis /
oxidative phosphorylation ,
do not occur ;

163
Q

Suggest why lactate is converted to pyruvate by the hepatocytes rather than the respiring cells in which it is produced (1)

A

hepatocytes can tolerate , lactate / low pH
(which would otherwise be toxic) ;
2 hepatocytes have / (other) cells do not have ,
enzymes , t o
metabolise lactate / catalyse this reaction ;
3 (conversion of lactate) requires oxygen and ,
muscle cells do not have enough oxygen /
2 O
is not available during anaerobic respiration

164
Q

State where in the liver cell that the excess reduced NAD is oxidised (1)

A

In the inner mitochondrial membrane

165
Q

Which reaction is catalysed by the enzyme RuBisCO?
A carboxylation of ribulose bisphosphate (RuBP)
B conversion of triose phosphate (TP) to ribulose phosphate (RuP)
C oxidation of glycerate-3-phosphate (GP)
D reduction of glycerate-3-phosphate (GP)

A

A

166
Q

Outline how a student could carry out a chromatography experiment to determine the pigments present in the leaves (4)

A
  • extract the pigments from the leaves by grinding them up
  • place a concentrated spot on the chromatography plate
  • put this in a small beaker containing a small amount of solvent
  • when the solvent has stopped moving, remove it and mark the solvent front
  • calculate the retention values
167
Q

What are two safety precautions that should be taken when doing paper chromatography ? (2)

A
  • wear gloves/goggles because many of the compounds are toxic
  • fume cupboard as the vapours are hazardous
168
Q

Give two chemical defences that plants can produce in response to be eaten by plants and explain how they work (4)

A

Alkaloids which are poisonous to many insects

Tannins which bind to protein in the animals guy making it hard for the plant to be digested

169
Q

How does ethene cause the plants to ripen? (1)

A

Breaks down cell walls / break down chlorophyll / convert starch into sugars

170
Q

State three ways in which lactate enzymes can be immobilised (3)

A

1 encapsulated in alginate beads
2 trapped in a silica gel matrix
3 covalently bonded to cellulose or collagen fibres

171
Q

Give two disadvantages of using immobilised enzymes in industry (2)

A

1 extra equipment needed
2 reduction in enzyme activity
3 expensive so not good for small scale production

172
Q

Give one example of an immobilised enzymes used in industry (1)

A

Penicillin acylase used in production of semi synthetic penicillins.
Glucoamylase for the conversion of dextrin a to glucose.
Glucose isomerase for the conversion of glucose to fructose

173
Q

Explain the process of somatic cell cloning and give some disadvantages (6)

A
  • nuclei extracted from the organism that’s being cloned
  • nuclei removed from the oocyte
  • electrofusion to stimulate the nucleus to be take up
  • cells stimulated to divide to produce embryos
  • an embryo is transplanted into a surrogate mother
  • reduced genetic variability
  • difficult / time consuming
  • may have health defects
  • unethical
174
Q

Plant growth can be reduced if the rate of the light independent reaction is limited. Explain one reason why (2)

A

Less GP converted to TP….
Less amino acids for protein production
Less glucose for releasing energy

175
Q

Give one example of a phenotypic trait in plants that is only determined by the environment and explain how it is caused (2)

A

Chlorosis - leaves turn yellow due to external factors such as limited magnesium to be able to produce chlorophyll

176
Q

Why does DNA need to be amplified before producing a DNA profile? (1)

A

To be able to see the DNA bands much easier

177
Q

Explain why DNA samples from different individuals produce different bands with different patterns when DNA profiles are produced? (4)

A
  1. The genome contains areas of repetitive, non-coding base sequences
  2. Different individuals have a different number of repeats at each loci
  3. DNA fragments corresponding to different numbers of repeats are separated according to size
  4. The pattern of bands produced corresponds to the number of repeats an individual has at each locus
178
Q

Give two disadvantages of somatic cell therapy (2)

A
  • effects may be short lived
  • multiple treatments needed
  • immune response may start against the virus vector
  • the gene may be overexpressed
  • may be inserted in the wrong place and could cause more problems
179
Q

A hydatidiform mole is a rare complication of pregnancy that can occur after implantation
of the fertilised egg in the uterus. It results in excessive production of hCG and damage to
the lining of the womb, leading to miscarriage.
Suggest how a hydatidiform mole could increase hCG above normal levels (3)

A

1 idea that (hydatidiform mole) cells produce more hCG than normal 
2 (due to) expression / up regulation , of genes 
3 synthesising more , hCG / protein(s) 
4 idea that other tissues could be stimulated to produce more hCG than normal 

180
Q

Discuss the benefits of using stains when making slides for light microscopy (3)

A

contrast is high(er) 
more (internal) structures visible 
some (named) organelles / cell components more visible , because they bind to stain 
clearer image can be obtained 

181
Q

In a microscope image, how do you identify the islets of langerhan and the acini tissue in the pancreus? (1)

A

The islets of langerhan are in a cluster where as the acini cells are not.

182
Q

Suggest how the interdisciplinary field of bioinformatics may be useful in determining whether a newly-sequenced allele causes a genetic disease (2)

A

base sequence of normal allele and (known) alternatives held (in database) 
computational analysis allows rapid comparison of sequences with newly sequenced allele 
amino acid sequence / protein structures, also held
(in database) 
idea of
computer modelling of new protein structure from base sequence 

183
Q

Suggest three ways in which the use of embryonic stem cells in research has practical benefits to biological knowledge (3)

A

(can be grown into different tissues to) test how effective new medicinal drugs are 
(can be grown into different tissues to) test for side effects / toxicity of new drugs 
(can be grown and) studied to see how they develop into different cell types (developmental research) 
cell function can be studied to find out what can make it fail to work properly in certain (named) diseases

184
Q

Suggest one advantage and one disadvantage of a kidney transplant compared to
dialysis (2)

A

advantage:
does not require repeated dialysis OR diet less limited OR better quality of life / no longer chronically ill 
disadvantage:
idea of difficulty finding donor organ OR risks of surgery OR risks from , organ rejection / long term immunosuppressant drugs 

185
Q

State a material used as the stationary phase in thin layer chromatography (1)

A

Silica gel

186
Q

State the precise location of photosynthetic pigments in the chloroplast (2)

A

Photosystems

Thalakoid membrane

187
Q

State three differences between electrophoresis and thin layer chromatography (3)

A
  • separates by absorption vs separates by size
  • TLC separates non charged molecules where as electrophoresis only can seperate charged molecules
  • electricity is used for electrophoresis compared to not in TLC
  • buffer solution for electrophoresis but not for TLC
  • electrophoresis is automated but TLC is not
188
Q

Compare DNA replication and transcription by describing the similarities and differences
between the two processes (6)

A
Similarities
• DNA unwinds and unzips
• Helicase enzymes
• Template DNA
• Complementary base pairing
• Hydrogen bonds
• Free, activated nucleotides
• Polymerase enzymes

Differences
• Only a small section of DNA (where the gene is located) unzips during transcription
• Both strands act as templates in replication
• RNA vs DNA free nucleotides
• RNA vs DNA polymerase
• Different helicase enzymes
• Products are two new daughter strands of DNA in replication and one mRNA strand in transcription
• mRNA leaves nucleus whereas the new DNA strand remains bound to the template strand

189
Q

Suggest why proteins are heated before being placed in the electrophoresis gel (1)

A

denature / unfold , protein AND idea of exposes charges or hydrophobic region

190
Q

Define a climax community (1)

A

final / stable / not subject to further succession

191
Q

Describe the difference betwen a pioneer community and a climax community (2)

A

1 pioneers arrive, before climax / earlier; ora
2 pioneer communities subject to, greater / more, change / succession / replacement; ora
3 pioneer community (usually) has, less / lower, biodiversity; ora
4 idea that pioneer community is (often) less, stable / self-sustaining; ora
5 pioneer community has lower biomass; ora

192
Q

What is the difference between decomposition and denitrification? (2)

A

1 decomposition is break down, dead matter / waste
or
decomposition is conversion of organic matter to inorganic;
2 denitrification is conversion of nitrates to nitrogen (gas);
3 decomposition increases, mineral / nitrate, supply
and
denitrification reduces, mineral / nitrate, supply;

193
Q

What is the difference between nitrogen fixation and nitrification? (2)

A

nitrogen fixation is the conversion of (atmospheric) nitrogen into, ammonia / ammonium compounds / ammonium ions;
2 nitrification is the conversion of, ammonia / ammonium compounds / ammonium ions, into nitrite / nitrate;
3 correct ref to microorganisms involvement in both processes;
- nitrogen fixation involves, Rhizobium / Azotobacter / Nostoc
and
nitrification involves, Nitrosomonas / Nitrobacter

194
Q

Describe how a student would use a belt transect to measure the distribution of the two buttercup species between the pond and the land (3)

A

lay tape measure out from edge of pond ✓
place quadrat beside tape measure ✓
identify species of buttercup in quadrat ✓
count number of plants of each species (in quadrat) ✓
repeat for positions of quadrat along tape ✓

195
Q
Which of the following statements describes a feature of peritoneal dialysis?1 Urea and mineral ions pass into the tissue fluid.2 Blood is passed over an artificial membrane to remove toxins.3 The patient receives immunosuppressant medication.
A          1, 2 and 3
B          Only 1 and 2
C          Only 2 and 3
D          Only 1
A

D

196
Q

Fluid is found in the tubes responsible for gaseous exchange in insects. Name this fluid (1)

A

Tracheal fluid

197
Q

Explain why is meant by a limiting factor (2)

A

the factor that will , determine / limit / AW , the rate

when at ,low(er) / sub-optimal / AW , level 

198
Q

Water can fill air spaces in the soil surrounding the roots.This prevents oxygen from reaching root hair cells. Using your knowledge of aerobic and anaerobic respiration, explain why overwatering can kill plants (6)

A

Aerobic respiration (A)(No oxygen so) no aerobic respiration occurs
No , link reaction / Kreb’s cycle / ETC / oxidative phosphorylation
No oxygen to act as the final , electron / hydrogen acceptor
Anaerobic respiration
Plant has to) switch to anaerobic respiration / only anaerobic respiration can occur
Only glycolysis occurs
Alcoholic fermentation occurs
NAD regenerated (for glycolysis)
Pyruvate to ethanal to ethanol
Named enzyme e.g. pyruvate decarboxylase
(Only) 2 ATP
ethanol is toxic
(alcoholic fermentation) is irreversible
Less ATP produced / only 2 ATP from glycolysis
Less / no , active transport
(root hair cells) cannot take up mineral ions (by active transport)
so (plant) cannot make , proteins / amino acids / DNA / chlorophyll etc
cannot generate water potential gradient (into roots) / water potential (in root hair cells) is too high
water cannot be absorbed (so cells cannot remain turgid)
less / no , photosynthesis

199
Q

Explain why a plant leaf is described as an organ (4)

A

organ iscollection/ AW, of tissues
perform / carry out / adapted to , function / role
leaves have two from: epidermis / spongy mesophyll / palisade mesophyll / vascular / phloem / xylem , (tissues)
(to carry out) photosynthesis/ gaseous exchange

200
Q

Nephrogenic diabetes insipidus is a disease of the kidney that affects the regulation of water potential in the blood. One cause is lithium poisoning. Lithium ions enter the kidney tubules through sodium channels.This prevents the cells of the collecting duct from responding to ADH in the blood.State and explain one symptom you would expect to observe as a result of nephrogenic diabetes insipidus (2)

A

symptom:
high volume of / excess , urine OR always thirsty / AW explanation:
fewer / AW , aquaporins in the (plasma) membrane (of collecting duct cells)

201
Q

Describe and explain the role of ATP in the cell (3)

A
  • releases energy
  • phosphate group can be removed by hydrolysis
  • energy released in small packets
  • ADP can attach to a phosphate during respiration
202
Q

Describe the ways in which an endothermic animal prevents its core temperature decreasing (5)

A
  • thermoreceptors detect this
  • hypothalamus then receives this info
  • vasoconstriction of arteriole story reduce heat loss
  • Increased metabolic rate to generate heat
  • adrenaline release
  • shivering to generate heat
  • erector muscles contract
203
Q

Fever is accompanied by sweating. Explain the effect that this sweating will have on the body (2)

A

1 evaporation will , have a cooling effect / reduce (body) temperature ;
2 heat , taken from / supplied by , the body / blood / skin , is , needed / used for , evaporation ;
3 idea that water has a high latent heat of , vaporisation / evaporation

204
Q

Suggest an explanation for the fact that action potentials are not generated constantly whilst wearing clothes (1)

A
1    sodium (ion) channels (remain) open/ resting potential not re-established ; 
2   idea of ions being in the wrong place for correct ion movement (across membrane) ;
205
Q

Describe and explain the difference between the functions of RNA and DNA polymerase (4)

A

RNA Polymerase:

  • makes mRNA
  • transcription
  • one strand used / formed

DNA Polymerase:

  • DNA replication
  • semi conservative
  • before cell/ nuclear division
206
Q

Describe how the equation for respiration is an over simplification (1)

A
  • glucose is not the only substrate
  • ATP is produced
  • ATP required
  • not a single step reaction
  • enzymes are involved
  • glucose does not react directly with oxygen
207
Q

Suggest three ways that farmers can maximise the efficiency of the transfer of energy up food chains from primary consumers to humans (3)

A

1 keep animals, warm / indoors;
2 reduce animal movement ;
3 feed animals high, protein / energy, food ;
4 vaccination / (routine) antibiotics, for animals;
5 selective breeding / genetic engineering, for improved animals ;
6 slaughter just before, mature / full size ;

208
Q

Which statements describe commercial uses of plant hormones?

Statement 1: Auxin powder is placed on the cut stems of plants to help them root.

Statement 2: Ethylene gas is used to speed up the ripening of harvested green bananas.

Statement 3: Gibberellin is produced by a seed during germination.
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1
A

B

209
Q

Which food will require the largest volume of oxygen for it to be oxidised completely?

A 1 g lipid
B 1 g monosaccharide
C 1 g polysaccharide
D 1 g protein

A

A

210
Q

Which of the following is an example of post-translational control of gene expression?

A A non-functional protein produced from edited mRNA
B β-galactosidase activity in Escherichia coli exposed to lactose
C Liver cells beginning glycogenolysis in response to glucagon.
D A Hox gene product acting as a transcription factor for many other

A

C

211
Q

18 The polymerase chain reaction (PCR) is a laboratory technique used to amplify DNA.
Which statements correctly describe aspects of this process?
Statement 1: When the temperature is at 55oC single-stranded DNA anneals to primers.
Statement 2: DNA copy number increases with each thermal cycle on a logarithmic scale.
Statement 3: The enzyme Taq polymerase is used because it catalyses transcription in a bacterium that lives in hot water.
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1

A

B

212
Q

Which of these statements is true of natural clones in mammals?
A They have identical nuclear genomes and, on average, 50% of the same mitochondrial genome.
B They share the same nuclear and mitochondrial DNA genomes.
C They share, on average, 50% of their nuclear genome but have identical mitochondrial genomes.
D They share, on average, 50% of their nuclear and mitochondrial genomes.

A

B

213
Q

A liquid broth containing bacteria undergoes three rounds of serial dilution. In each case 1 cm3 of the starting solution is mixed with 9 cm3 of water. 1 cm3 of the final solution is plated onto agar and 39 colonies grow.
Calculate the number of bacteria in 1 cm3 of the original broth.
A 390
B 3 900
C 39 000
D 390 000

A

C

214
Q

What conversion is carried out by nitrifying bacteria as part of the nitrogen cycle?

A Ammonium compounds are converted to nitrites and nitrates.
B Atmospheric nitrogen is converted to nitrates.
C Nitrates are converted to atmospheric nitrogen.
D Nitrates are converted to ammonium compounds.

A

A

215
Q

State three differences in the structures of starch (amylose) and cellulose molecules (3)

A

coiled no coiling (contains)
α / alpha / A / a ,-glucose (contains) β / beta / B / b , -glucose ;
α / alpha / A / a 1-4 glycosidic bonds β / beta / B / b 1-4 glycosidic bonds ;
all , monomers / AW , in same orientation alternate monomers at , 180° / AW , to each other ;
granular / not fibrousfibrous / not granular ;
H bonds within molecule / no (H) bonds (between molecules) (H) bonds between adjacent molecules

216
Q

Describe how the guard cells surrounding the leaf pores are adapted to their role (2)

A

dea of: unevenly thickened (cell) wall ;
able to, change shape / bend ;
transport proteins / ion pumps, in plasma membrane ; (presence of) chloroplasts (to provide, ATP / energy) ;2

217
Q

The cohesion-tension theory is often used to explain the mechanism by which water movesup the xylem from the roots to the leaves.Use this theory to explain how water moves from the roots to the leaves (4)

A

evaporation at top of, plant / xylem ;
(creates) tension in xylem ;
water molecules, stick together / are cohesive / form a chain or column ;
(column / chain) pulled up (by tension);

218
Q

State two adaptations of sieve tubes that enable mass flow to occur (2)

A

1 elongated elements ;
2 elements , joined end to end / form column ;
3 sieve plates / pores in end walls / perforated end plates / sieve pores ;
4 little cytoplasm / cytoplasm pushed to cell edges / thin (layer of) cytoplasm;
5 no nucleus / few organelles

219
Q

State and explain two adaptations of leaves that reduce evaporation (4)

A

1] hairy leaves ;trap water vapour / moisture ; [A 2]stomata, in pits / sunken ;pits trap, water vapour / moisture ;
3] rolled leaves / presence of hinge cells;reduce surface area OR(rolled leaves) trap water vapour / moisture ;
4] high solute concentration in cells ; reduces water potential inside leaf cells ;
5] thick(er) cuticle;(which is) waterproof / (relatively) impermeable;
6] smallleaves / needles;smaller surface area;
7] fewer stomata; reduces diffusion (of water vapour) ; 8] stomata close, during the day ; reduces diffusion (of water vapour) ;
9] most stomata on lower surface ; less exposure to sun OR cooler OR reduces diffusion (of water vapour

220
Q

Some chemicals can act as allergens. If these allergens are inhaled, they can cause breathing problems. Allergens cause the smooth muscle in the walls of the airways to contract. Suggest the effects that this muscle contraction has on ventilation (2)

A

1 reduction in (lumen) diameter of, bronchi/bronchioles
2harder to exhale / more resistance to exhalation /less aircan be exhaled
3more air remains in the lungs
4harder to inhale / more resistance to inhalation /less aircan be inhaled
5harder to ventilate / more resistance to ventilation/ increased breathing rate/ gasping

221
Q

Suggest why the resistance of MRSA to existing antibiotics is of major concern to humans (2)

A

MRSA / it, is harder to treat / may become untreatable ;
potential for, disease outbreak / epidemic / pandemic / killing many people
;developing new / more powerful, antibiotics, is expensive / takes time

222
Q

he wild ancestor of the domestic chicken is the red jungle fowl found in the rainforestsof South East Asia.Explain why it is important to preserve the population of the red jungle fowl (2)

A
1 maintain biodiversity ; 
2aesthetic (reasons) / tourism ; 
3ethical (reasons) ; 
4part of a food chain / web ; 
5maintain / increase gene pool; 
6genetic resource / availability to breed with domestic chickens
223
Q

State three differences in the ways in which plant and mammalian hormones operate (3)

A

1 (M) made in endocrine glands versus (P)made in many plant tissues ;
2 (M) move in blood versus(P)move, in xylem / in phloem / from cell to cell ;
3 (M) act on, a few / specific / target, tissues versus (P)act on most tissues / can act in cells where produced 4 (M) act more rapidly

224
Q
Define the following terms:
producer
consumer
trophic level
(3)
A

producer (leaves / plants) fix carbon / photosynthesise / make food / autotroph(ic) / convert light energy to chemical energy / convert inorganic, C / CO2, to organic molecules

consumer (bird) eat / derives energy from / feeds on , other organisms or heterotroph(ic)

trophic level stage / position / place / level , in a food , chain / web

225
Q

The farmer does not wish to use inorganic fertiliser to replace the nitrate in the soil of thecabbage field. She wishes to make use of nitrogen fixation. Suggest a crop she could plant that would allow this to occur and explain how this would add nitrate to the soil (3)

A

1 legume / any named leguminous plant ;
2 Rhizobium / nitrogen-fixing bacteria (in root nodules) 3 idea of converting nitrogen gas / N2 , into ,compounds / ammonium / ammonia / amino acids / protein (in plants)
4 plants ploughed in / plants left to decay /

226
Q

Why is the continued existence of rare breeds of farm animals desirable? (2)

A

1 genetic resource / gene bank / have (different) alleles ;
2 for , genetic engineering / genetic modification / artificial selection / selective breeding / described
3 if conditions change / in the future
4 example of useful trait
5 to maintain, biodiversity / genetic diversity / (large) gene pool

227
Q

Explain the differences between conservation and preservation (2)

A

1 conservation maintains , ecosystem / biodiversity / species / habitats or conservation involves , active / sustainable , management of , ecosystem / resource / habitat
2 preservation leaves , ecosystems / habitats undisturbed

228
Q

Describe the proccesses that lead to the release of insulin from beta cells (4)

A

1 glucose , respired / phosphorylated / metabolised , to produce ATP ;
2 ATP , blocks / closes , potassium ion channel(s) andpotassium ions / K+, build up (inside cell) / cannot leave ; 3 (voltage-gated) calcium ion / Ca2+, channels open andcalcium ions / Ca2+, enter (cell by diffusion)
4 (more) calcium ions / Ca2+, resulting in , movement of vesicles to membrane /exocytosis / described

229
Q

Outline the organisation and roles of the autonomic nervous system in mammals (6)

A
  • (two parts are) sympathetic and parasympathetic
  • S uses noradrenaline but P uses acetylcholine
  • S, fight / flight / stress, but P, rest / relaxation / calm
  • S increases,heart rate / cardiac output / blood pressure, but P reduces this;
  • S increases, speed / rate / depth, of breathing, butPreduces this
  • S increases airway diameter but P reduces it ;
  • S increases blood flow to skeletal muscle but Pincreases blood flow to gut (smooth muscle)
  • S dilates pupils but P constricts pupils
  • S makes liver release glucose, but P makes liver,store / take up,glucose
230
Q

Explain why dwarfism can be described as a genetic condition (2)

A

inherited / passed to offspring / passed (down) from parents

(caused by) mutation / allele;

231
Q

Name the tissue that lines the proximal convoluted tubule (1)

A

Epithelial

232
Q

Explain how changes in concentration in the blood are brought about by the proximal convoluted tubule (3)

A
  • selective reabsorption;
  • of glucose and amino acids ;
  • co-transport / facilitated diffusion / uptake described ;
  • water follows by osmosis so concentration of, ions / nitrogenous waste / urea / remaining substances , increases ;
233
Q

Suggest why it is necessary to add an anticoagulant to the blood in dialysis (1)

A

so that clots don’t form, whilein the(dialysis) machine / during dialysis

234
Q

Suggest why no anticoagulant is added to the blood towards the end of a dialysis session (1)

A

idea of allowing blood to clot normally after treatment

235
Q

Suggest why patients receiving peritoneal dialysis usually need to have the peritonealdialysis fluid replaced four times a day, but those receiving haemodialysis only needtreatment three times a week (2)

A
  • peritoneal dialysis can remove less (named)waste (than haemodialysis)
  • in haemodialysis dialysis fluid is constantly ,refreshed / changed (but not in peritoneal dialysis) ; - haemodialysis uses counter-current flow ;
  • idea that haemodialysis maintains concentration gradient or in peritoneal dialysis the concentration gradient , reduces / is lower ;
  • (in peritoneal dialysis) the fluid reaches equilibrium with the blood
236
Q

(c) If oxygen is not present or is in short supply, respiration can take an anaerobic pathway afterglycolysis. In plant cells, this pathway is the same as the one used in yeast cells.
(i) Name the hydrogen acceptor in this pathway. ……………………………………………[1]
(ii) Name the intermediate compound in this pathway. ………………………………………….[1]
(iii) Name the products of this pathway. …………………………………………….[1]

A

1 ethanal
2 ethanal
3 ethanol and carbon dioxide

237
Q

Explain why aerobic respiration is important to plants (2)

A

1 releases NAD , to accept more H / to be reduced again / so glycolysis can continue or allows (some) ATP to be generated (in glycolysis) ;
2 (some ATP available) for named cellular process eg:
(active transport, endocytosis / exocytosis , mitosis / meiosis, protein synthesis, DNA replication, Calvin cycle / light-independent stage of photosynthesis

238
Q

State the stage or stages of aerobic respiration during which:

(i) carbon dioxide is produced [1]
(ii) oxygen is used [1]

A

(i) link cycle and krebs cycle

(ii) oxidative phosphorylation

239
Q

Explain why there is an increased rate of respiration in soaked seeds at 25 °C compared with soaked seeds at 15 °C (2)

A

increased kinetic energy ;

(named respiratory) enzymes / decarboxylases / dehydrogenases involved

240
Q

Compare anaerobic respiration in yeast and mammals.

  • Name of hydrogen acceptor after glycolysis
  • CO2 produced?
  • name of final product
A
Mammals:
- pyruvate 
- no
- lactic acid
Yeast:
- ethanal
- yes
- ethanol
241
Q

Explain how the three reaction pathways (Krebs, Calvin, Glycolysis) are able to work independently of each other in the same leaf cell (3)

A

take place in different , parts / organelles , of the cell or compartmentalisation / reactions separated by membranes ;
W / glycolysis , in cytoplasm ;
X / Calvin cycle , in , chloroplast /stroma (of chloroplast) Y / Krebs cycle , in , mitochondrion / matrix (of mitochondrion

242
Q

Describe how the structure of the cell walls in xylem vessels would differ from the cell walls in meristematic cell tissue (2)

A

thicker ;
lignified ;
contain (bordered) pits

243
Q

Discuss the ways in which genetic variation is produced, including the role of nuclear division (8)

A

A1 independent assortment / random segregation , of(homologous) chromosomes / bivalents;
A2 in , metaphase I / meiosis I;
A3 of chromatids in , metaphase I I / meiosis I I ;
A4 (so) homologous chromosomes , have different alleles / come from different parents ;
A5 produces large number of allele combinations ;
C1 crossing over / (formation of) chiasma(ta) ;
C2 in , prophase I / meiosis I ;
C3 (so) chromatids will have new combination of alleles C4 amount of variation depends on distance between crossover points ;
M1 mutation ;
M2 changes the (DNA) nucleotide/ base, sequence ;
M3 DNA checks (during duplication) did not recognise damage ;
M4 idea of differences in (named) protein(s) ;
N1 non-disjunction ;
N2 homologous chromosomes do not separate (in metaphase I) ;
N3 one , more / less , chromosome present ;
F1 random, mating / fusion of gametes/fertilisation ;
F2 gametes are not genetically identical;
F3 produces large number of (allele) combinations

244
Q

Explain what is meant by a homologous pair of chromosomes (3)

A
1 one maternal and one paternal / 
2 carry same genes;
3 carry, same / different, alleles ;
4 (usually) same / similar, length ;
5 centromere in same position ; 
6 same banding pattern ; 
7 pair up in meiosis / form bivalent
245
Q

Name two parts of a plant where meristematic tissue can be found (2)

A

(just behind) tip / apex , of root ;
(just behind) tip / apex , of shoot ;
cambium / pericycle / vascular bundle ; bud ;

246
Q

State three reasons why mitosis is important to organisms (3)

A

growth (of tissue / organism) ;
replace (cells) / repair (tissues) ;
asexual reproduction/cloning / producing genetically identical cells;
maintain chromosome number in all cells

247
Q

Suggest why it is not possible to expel all the air from the lungs (2)

A

thorax / rib cage / lungs, cannot be completely , compressed / flattened ;
trachea / bronchi, held open by cartilage ;
bronchioles / alveoli, held open by elastic fibres

248
Q

State the name of the process by which new species arise and suggest the mechanisms necessary for this process to occur (3)

A
  • speciation;
  • isolation / separation, (of populations)
  • further detail of isolating mechanism e.g. volcano/ river
  • mutation / genetic variation
  • natural selection / description of natural selection
  • different selection pressure(s) (in different environment)
  • (enough) time to allow changes in population to prevent interbreeding
249
Q

Outline the main steps involved in cloning plants via tissue culture (5)

A
  • meristematic/ totipotent/ undiffernciated tissue
  • sterile conditions
  • nutrient medium to encourage mitosis
  • produces a callus
  • subdivided
  • grows into plantlet
250
Q

State 3 advantages of tissue culture (3)

A
  • can be done at any time of year
  • deseribale characteristics always passed on
  • faster method
  • produces many plants
  • disease free
251
Q

List 3 constituents of the culture medium (3)

A
  1. sucrose
  2. amino acids
  3. vitamins
  4. water
  5. auxins
252
Q

Suggest 3 reasons why micropropagation may be more expensive than other methods (3)

A
  • specalist workers needed
  • special equipment
  • labour intensive
  • sterile conditions
253
Q

State the meaning of an immobolised enzyme (1)

A

An enzyme which is attached to an insoluable material

254
Q

Describe two practical considerations to ensure the S. cerevisiae population grows successfully when the initial culture is established (2)

A

aseptic techniques / avoid contamination
provide (sources of) nutrients / respiratory substrates (incubate at) suitable temperature
use (pH) buffer
agitation / stirring / shaking

255
Q

A diploid cell contains three pairs of homologous chromosomes. Each pair is heterozygous for a pair of alleles, Aa, Bb and Cc respectively.
If this diploid cell undergoes meiosis, how many different combinations of these genes could be produced in the haploid daughter cells?
A 6
B 8
C 16
D 64

A

B

256
Q
How many mitotic divisions of a meristematic cell in a root tip are needed to produce 256 daughter cells?
A	8	
B	16	
C	32	
D     64
A

8 (2^8)

257
Q

Explain why glucose is needed for contraction of skeletal muscle (3)

A

(glucose) for respiration / as respiratory substrate / to release energy 
to produce ATP 
ATP needed (in muscle contraction) for breaking
cross-bridges between myosin and actin / AW 
ATP , hydrolysed / to ADP and Pi , to
reset myosin heads 
ATP for active transport of calcium ions (back)
into sarcoplasmic reticulum 

258
Q

Outline the importance of photosynthetic pigments in photosynthesis (4)

A
  • pigments absorb light/photos
  • accessory pigments pass energy to ,
    reaction centres / primary pigments 
  • primary pigments , become oxidised /
    lose electrons / pass electrons to ETC 
  • for light dependent reaction / photophosphorylation
259
Q

State and explain how one feature of the plasma membrane contributes to its stability (2)

A
property -
hydrophobic (region / fatty acid tails) 
explanation -
(helps to) form bilayer / separates two aqueous regions 
property - 
(region) contains cholesterol 
explanation - 
regulates (membrane) fluidity
260
Q

Outline the role of membranes within cells (2)

A

compartmentalisation
OR
form / surround , (named) organelles 

purpose of / need for , compartments / separation

sites of , chemical reactions / electron carriers /
photophosphorylation / chemiosmosis /
oxidative phosphorylation 

provide attachment sites for , enzymes / pigments

allow formation of concentration gradients

261
Q

Outline the processes involved in the generation of ATP through chemiosmosis (6)

A

Points mentioned

  • involves inner membrane and matrix
  • involves movement of H+ across the membrane
  • use of enzyme / ATP synthase
  • H+ pumped out of the matrix
  • H+ gradient
  • ATP synthase produces ATP from ADP and an inorganic phosphate

Points missed out
- occurs in mitochondria
- H+ ions pass through hydrophilic transmembrane
protein
- H+ ions move from area of high concentration to
low concentration
- Some H+ ions leak back into matrix / process is not
completely efficient
- cristae

262
Q

Explain how TTX affects the activity of neurones if it binds to voltage - gated sodium ions and stops them opening (4)

A
  • sodium ions / Na ions / Na+ , cannot enter 
  • no / prevents , depolarisation of membrane 
  • (membrane) remains at resting potential 
  • prevents action potential being generated 
  • impulse not conducted (along axon) 
  • (so) no release of neurotransmitter 
263
Q
Which of the following types of cells will not be involved in the primar immune response? (1)
A T - Memory
B T - Helper
C T - Killer
D plasma cells
A

A

264
Q

Desribe and explain how one feature of the lungs provides an efficent gas exchange surface (2)

A

large surface area
for (maximum) diffusion

squamous, epithelium / cells OR alveolar wall, only 1 cell thick / thin
(providing) a short diffusion distance

Good, blood supply / ventilation
maintaining / creating a (steep) concentration gradient

265
Q

Suggest two ways in which the student could have ensured confidence in their results (2)

A
  • repeats
  • calculate mean
  • identify anomolies
  • use statistical test to identify differences
266
Q

Explain why the surface area to volume ratio of an organism determines whether it needs a circulatory system (3)

A

large(r) organism has small(er) SA : Vol ratio
(rate of) diffusion (too) slow / diffusion distance (too) long
for (sufficient), delivery / uptake of, oxygen / nutrientsOR for (sufficient) removal of (named) waste products
for, (aerobic) respiration / metabolic demand

267
Q

Name 3 functions of triglycerides in living organisms (3)

A
  • thermal insulation
  • electrical insulation
  • protection for organs
  • energy storage
  • buoyancy
268
Q

Explain the melting points of three molecules decreasing when the number of hydrogen atoms decreases (2)

A
  • less saturated molecule means more kinks

- less uniformly packed together

269
Q

Outline a practical method that could be used to determine the density of hairs on the underside of the leaf (3)

A
use a microscope
use a graticule/ calibrate 
count number hairs per (unit) area
repeat (measurements on same leaf) 
calculate mean(leaf hair density) 
divide by area used (to calculate density)
270
Q

Why do plants further away from the river have an increased number of leaf hairs? (2)

A
  • further away from the river means less water (available)
  • transpiration causes water loss
  • hairs,trap water vapour/ reduce transpiration / reduce loss of water (vapour)
  • reduced water (vapour) potential gradient from inside to outside leaf
271
Q

Explain why transcription is needed for long polypeptide synthesis (2)

A

1 gene / DNA, copied/ transcribed,to (m)RNA
2 (idea that RNA goes to / translation is at) ribosome(s) / RER
3 DNA,is too large to/ cannot / is not able to,leave nucleus / cross nuclear envelope / fit through nuclear pores

272
Q

Compare the properties and functions of fibrous and globular proteins (6)

A

FIBROUS PROTEINS
Properties:•
insoluble•
elongated / long / rods / filaments / ropes / strands• strong / tough•
flexible
IGNORE size refs / compact / coiled / bond types / hard
Functions:
(structure) collagen in, bone / cartilage / connective tissue / tendons / ligaments / skin / blood vessels
fibrin + role described•
for protection•
keratin in, skin / hair / nails•
to give, elasticity / elastic properties•
elastin in, (named) blood vessels / alveoli / cartilage• for, contraction / mechanical movement•
actin / myosin, in muscle•
microtubules in, cilia / flagella / spindle / cytoskeleton

GLOBULAR PROTEINS
Properties:•
soluble•
spherical / ball-shaped•
have, 3D / tertiary / 3o, shape / structure•
specific / complementary (to another molecule)•
ref. conjugated / contain prosthetic group• temperature / pH, sensitive•
hydrophilic on outside
Functions:
enzymes / metabolic role / to catalyse reaction(s) / to lower activation energy•
named enzyme + its specific role described• hormones / receptors / for cell signalling•
named hormone / insulin + role described•
antibody / for immunity / defence against infection• opsonin / antitoxin / agglutinin + role described• fibrinogen in bloodclotting•
to transport substances across cell membranes• carrier / channel / pump + role described•
to transport substances in blood•
haemoglobin + role described e.g. carry oxygen•

273
Q

A student did a method to work out which amino acids were in a sample.
This is the method used:
1 Draw a pencil line 1cm from the bottom of the chromatography plate, put solvent to 0.9cm
2 Hold the paper in your hand and lower it into the beaker
Suggest 4 improvements which could be made (4)

A

1 put pencil line / origin / amino acids, higher (than the solvent / 1cm) +1 R to stop, spots / samples / amino acids,dissolving into / mixing with / touching, solvent
2 put, amino acids / spots / them, further apart / on separate plates+2R to stop them, merging / touching / clashing / AW
3 touch plate edges / wear gloves / use forceps / don’t touch middle, to prevent, contamination / transfer of substances from hands
4 place, lid / cover, over beaker to prevent evaporation (of solvent)
5 support the plate / attach plate to beakerto keep plate, vertical / still / at constant height
6 use ninhydrin to, see / visualise, amino acids
7 repeat and find, mean / average (Rf value) to improve, accuracy / check for repeatability / exclude anomalies
8 label, amino acids / spots / samples (in pencil / on beaker) to know which is which / avoid confusion

274
Q

Explain how electricty activity controls ventricular systole (2)

A

1 impulse OR(wave of) depolarisation ORwave of excitation
2correct ref.atrioventricular node / AV node / AVN
3 (through / along)bundle of His/ Purkyne fibres,to (cause contraction of) ventricles

275
Q

State how the cytoskeleton moves organelles around the cell (1)

A

microtubules/ tubulin / motor protein

276
Q

Explain the function of the epithelial cells in the airways of mammals and the importance of the cytoskeleton in carrying this out (4)

A

1 goblet cells,secrete / release / make / produce / form, mucus
2mucus traps, pathogens/ microorganisms / bacteria
3ref. phagocytes / neutrophils / macrophages / lysozyme
4cilia/ ciliated cells / ciliated epithelium, sweep / brush / waft / move / AW, mucus
5cytoskeleton / microtubules / tubulin, move(s) / make(s) up, the cilia

277
Q
In which of the following processes do bacteria not play an active role?
A Bioinformatics
B Bioremediation
C Cheese - Making
D Manufacturing human insulin
A

A

278
Q

How do you know if something is a light microscope? (2)

A

magnification , (only) 1000 / < 2000 / within LM range
• colour visible
• (other) subcellular structures / (named) organelles , not visible
• wide field of view

279
Q

Apart from growth and repairs, what are the other roles of mitosis in multicelluar organisms? (1)

A
  • asexual reproduction
  • development of body plan
  • proliferation of white blood cells (clonal expansion)
  • producing gametes from haploid cells
  • production of new stem cells
280
Q

Explain, with refernce to selective breeding, why it is important to maintain viable wild populations of crop plant species (6)

A
genetic variation
genetic resource / gene bank 
source of useful alleles
can be cross bred with crop varieties
allows introduction of different traits
unknown future requirements 
potentially useful in changing climate
prevention of inbreeding depression 
promotion of hybrid vigour
prevent dwindling gene pool 
source of replacement if cultivated population is in danger
281
Q

Explain the purpose of a control bacterial plate which contains no bacterial broth (2)

A
  • control

- shows that bacterial growth is only due to the bacteria being cultered (idea of checking for contamination)

282
Q

Suggest why the teacher told the students not to grow the bacteria at 35 degrees (1)

A
  • human pathogens / harmful pathogens can grow
283
Q

Suggest why doing repliates helps to improve an investigation (3)

A
  • reduces impact of anomolies
  • measure repeatability
  • allows a calculation of a statistical test
  • mean is more likely to be close to the true value
284
Q

Explain why a gentic bottleneck can lead to low genetic diversity (2)

A
alleles lost (when population dropped) 
(modern population) descended from few survivors
285
Q

Explain how DNA sequencing allows the sequence of amino acids in a polypeptide to be predicted 92)

A
  • 3 bases/a codon codes for an amino acid

- order of bases codes for order of amino acids

286
Q

Outline how DNA sequencing and bioinformatics could be used toincrese the effectiveness of a vaccination programme against ebola (4)

A

Sequencing -
high) mutation (rate) means many , strains / AW , of virus exist
can predict (viral) , strain / protein / antigen
vaccine contains correct antigen
Bioinformatics
facilitates access to large amount of data
facilitates access to data on DNA and proteins
idea that format (of information) is universal
can identify source of outbreak
can identify vulnerable populations
vaccination program can target certain , area / individuals

287
Q

What is the normal function of IAA in a plant? (1)

A

cell enlongation

288
Q

The herbicide atrazine works by disabling plastoquinone, one of the proton pumps in photosystem II. Explain how atrazine would kill a susceptible plant (5)

A

1reduced / no,proton pumping / proton motive force / chemiosmosis
2photophosphorylation stops
3less / no,ATP produced
4less / no,reduced NADP produced
5no,Calvin cycle / carbon fixation / light independent stage
6no,TP / (hexose) sugars,made
7no respiratory substrate / respiration ceases

289
Q

What are 2 examples of non reversible enzyme inhibitors? (2)

A
  • cyanide

- aresenic

290
Q

What is the name of the action where animals synapes have multiple stimuli which result in one response? (1)

A
  • spatial summation
291
Q

By appearance, how can yo tell the difference between the hepatic portal vein and the hepatic artery? (1)

A

Hepatic artery as blood entering liver through narrow vessel
Hepatic portal vein as blood (from gut) entering liver through branched vessel

292
Q

Suggest 2 ways in which the ultrastructure of the chloroplast can be altered by high temperatures? (4)

A

1a damage to chlorophyll / reduction in pigment
1b which will reduce the light dependent stage
2a damage to membranes in chloroplast / reduction in sites for light capture
2b which will reduce the light dependent stage
3a damage to membranes in chloroplast / reduction in reaction sites for electron transfer
3b which will reduce,photophosphorylation / ATP production in the light dependent stage
4a damage to membrane around chloroplast / release of enzymes
4b which will reduce,light independent stage / Calvin cycle

293
Q

Suggest why is is beneficial for a plant to transfer their carbohydrate to be transferred as sucrose rather than another carbohydrate (2)

A

1 soluable

2 metabolically inactive

294
Q

How is transport in the phloem similar and different to that in the xylem? (2)

A

similar -
solutes carried in solution in both
both carry mineral salts
both use, mass flow / generated hydrostatic pressure different –
transport in phloem can take place in different directions and transport in xylem only takes place up the plant
phloem carries carbohydrates and xylem does not phloem transport uses living cells and xylem does not xylem uses, capillary action / cohesion and adhesion,and phloem does not

295
Q

Describe the sequence of actions that occur once adenylyl cyclase is activated in liver cells? (2)

A

catalyses synthesis of cyclic AMP from ATP

cyclic AMP activates enzymes responsible for conversion of glycogen to glucose

296
Q

Suggest how an allele may inhibit the expression of another allele by epistasis (2)

A

B, produces / codes for, repressor protein /
repressor polypeptide / enzyme / transcription factor 
(protein / polypeptide / product of B) binds to, promoter (of A)
/ mRNA / ribosome 
(product of allele B) stops, transcription / translation (of allele A)
/ protein synthesis / described
product of B inhibits the enzyme (encoded by A)

297
Q

Describe the production of ATP by substrate - level phosphorylation in different stages of respiration with reference to the number of ATP produced (4)

A

-2 (ATP molecules per glucose) from, glycolysis
-(when) triose (bis)phosphate / TP, converted / broken down,
to pyruvate 
-ref to net yield of 2 (ATP) / 4 (ATP) made but 2 used up
( in glycolysis) 
-1 ATP (produced) per, (turn of the) Krebs cycle / acetyl (coA) 
-when 5-carbon compound is converted to, 4-carbon compound / oxaloacetate

298
Q

Explain how temperature has a greater effect on the light independent stage rather than the light dependant stage (2)

A

1 light-independent stage is) controlled by (named) enzymes 
2 idea that higher temperature will increase, kinetic 3 energy of enzyme molecules / number of successful collisions /ESCs
formed / ora 
4 enzymes may be denatured at high temperatures / described

299
Q

Complete. The tissue sample removed from a plant is called the _____ ? (1)

A

Explant

300
Q

Explain why PCR may not be able to complete as much cycles in practice (1)

A

-temperature damage to, template / strand / fragment -(sometimes, once separated) template / strands, may rejoin
(rather than bonding to primers) 
-lack of, primers / (free) nucleotides 
-primers fail to, join / attach / anneal (to fragment

301
Q

What is one differnce between the action of somati cell therpay compared to germ line therapy? (1)

A
  • somatic tissue can target specific tissue in need of treatment which germ line therapy cant do
302
Q

Outline the processes which lead to the production of antibodies against an unfamilar bacterium (3)

A
  • B cells/ lymphocytes, have,antigenreceptor / carry antibody,on surface,specific / complimentary to, only one antigen
  • selected / activated, B cell, proliferates / clones/ divides by mitosis
  • forms/ differentiates into, plasma / effector, cells
  • which secrete antibodies specific / complementary, to antigen
303
Q

Describe 2 economic advantages of immobolising enzymes for large - scale production

A
  • reused so less money/cost
  • purifying cost reduced
  • more profit from faster yield
304
Q

Give comparisons of cuttings compared to micropropagation (2)

A
  • cuttings needs less and propogation needs more equipment
  • microprogogation needs more staff
  • cuttings roduces less offspring
305
Q

What are the steps that occur to ammonia for plants to be able to take up the nitrogen and what bacteria are involved? (4)

A

Nitrosomonas
ammonia to nitrite
Nitrobacter
nitrile to nitrate

306
Q

What is the hydrostatic pressure and oncotic pressure like at the arterial end of the capillary and the venous end? (1)

A

The hydrostatic pressure is higher at the arterial end.

The oncotic pressure is the end at both ends.

307
Q

What are some adaptations of hydrophytes? (2)

A

no / thin, (waxy) cuticle and idea that wax production is a waste (1)
large surface area to, increase / maximise, photosynthesis, as transpiration is not an issue (1)
many stomata to, increase / maximise, gas exchange (1) stomata on the top surface, as gas concentration is higher in air than water

308
Q

Explain how the casparian strip stops ions from passing through the endodermis layer? (2)

A

strip is impervious to, water / solutions (1)
forces water / solutions, to pass through, plasma / cell surface, membrane (1)
phospholipid (bilayer), repels / AW, ions / charged particles (1)

309
Q

Explain how mass flow of the phloem sap occurs in plants with a vascular system (3)

A

1 sugar / sucrose / assimilates, in the sieve tube (elements) ✓
2 (assimilates) enter, sieve tube / phloem (at source) and lowers water potential (in sieve tube)✓
3 water enters (sieve tube), by osmosis / down water potential gradient / described and increases hydrostatic pressure ✓
4 (assimilates) leave, sieve tube / phloem (at sink) and increases water potential (inside sieve tube) ✓
5 water leaves (sieve tube), by osmosis / down water potential gradient / described and lowers hydrostatic pressure ✓
6 (assimilates) move, from high to low (hydrostatic) pressure / down pressure gradient

310
Q

Explain why water molecules can form hydrogen bonds with nitrate (NO3–) ions (2)

A
water is (a) polar (molecule) ✔ 
nitrate (ion) / NO3–, is, charged / negative ✔ 
(hydrogen bonds form) between H on water and O on nitrate
311
Q

Describe the roles of the sinoatrial node (SAN) and the atrioventricular node (AVN) incoordinating the cardiac cycle (3)

A

SAN, is pacemaker/initiates heart beat ;
(SAN sends) impulse / wave of excitation, over atria (walls) ;
AVN delays impulse ;
(AVN) sends impulse down, septum / bundle of His / Purkyne fibres

312
Q

Describe how the action of the heart is initiated and coordinated (5)

A
  • T / SAN, creates / initiates / starts / originates, excitation
  • wave (of excitation) spreads over atrial, wall / muscle; ref to, AVN / U ;
  • atria contract / atrial systole ; contraction is synchronised / AW
  • delay at AVN
  • (excitation spreads) down septum
  • ref to, bundle of His / Purkyne fibres
  • ventricles contract / ventricular systole, from, apex / bottom
313
Q

Explain why a protein that is 175 amino acids long is coded for by 528 base pairs of DNA (3)

A

triplet code or 3 bases = 1 amino acid ;
525 ;
3bases are , stop / (chain) termination , codon

314
Q

Describe two ways in which hormones may alter a plant’s growth in response too overcrowding by other plants (4)

A

auxin / IAA
(positive) phototropism
plants / shoots, bend towards light
etiolation / plants grow taller
climbing plants climb, up / over, other plants
(positive) thigmotropism / sense of touch
grow roots towards, water / minerals

315
Q

Suggest how hormones alter a plant’s growth if the top of the plant shoot is eaten by an animal (3)

A

less auxin / auxin production stopped
apical dominance, stopped / removed
side shoots grow / lateral buds develop / ora
plant becomes bushy

316
Q

The number of small squirrels increases initially, but then decreases. Explain, using your knowledge of factors affecting population growth, why the small squirrel population in this rainforest does not increase in size indefinitely (4)

A
limiting / density-dependent, factors ; 
carrying capacity; 
intraspecific competition ; 
for, food / nesting sites ; 
interspecific competition 
parasites spread more easily
317
Q

Outline three reasons for conserving biological resources, such as the rainforest in Sarawak (3)

A

aesthetic / amenity / recreational, value
(eco)tourism
to, preserve biodiversity / preserve genetic diversity / stop extinction
ref. interactions between species / need to preserve whole habitat ;
(rainforest species / preserve gene pool as could be useful, in future / as potential, for, medicine / genetic engineering / AW ;
to support indigenous peoples / AW ;
to stop effect of deforestation on, atmosphere / climate / soil

318
Q

As the sugar concentration decreases the ethanol concentration increases in a yeast fermentor increases. Explain this relationship (3)

A

1 sugar converted to ethanol ;
2 in anaerobic respiration ;
3 sugar , undergoes glycolysis / converted to pyruvate ; 4 pyruvate , loses carbon dioxide / decarboxylated / forms ethanal ;
5 reduced NAD giving hydrogen to ethanal ;
6 idea of NAD being , regenerated / recycled , (so) glycolysis continues ;
7 correct ref to , pyruvate decarboxylase / ethanol dehydrogenase ;

319
Q

Discuss the benefits of using immobilised enzymes for large-scale production (4)

A

(enzyme) can be re-used so reduces cost ;
product, pure(r) / uncontaminated ;
reduced downstream processing costs ;
(immobilised enzyme) works at high(er) temperature ; (immobilised enzyme) works in changed pH ;
reaction, can be faster / have higher yield , because can be done at higher temperature

320
Q

HGH made in this way is given by injection to some children who have a genetic mutation. The mutation means that they do not produce enough HGH to enable them to grow atthe normal rate.Explain why injecting recombinant HGH in this way is not an example of gene therapy (3)

A

cells / DNA / genes / alleles ,not changed;
vector not used (in child) ;
child / cells , not producing , HGH / hormone ;
HGH / drug / injection , has to be given repeatedly / is a short term solution / not a cure

321
Q

Describe how a method that uses a colorimeter and Benedict’s reagent could be calibrated to measure the concentration of lactose in an unknown sample (4)

A
1 zero the colorimeter / set to zero 
2 using blank 
3 use red filter 
4 use known concentrations (of lactose) 
5 (produce) serial / series, dilutions 
6 construct calibration curve 
7 test unknown sample (using the same method) 
8 use / read from, graph / calibration curve, to determine (unknown) concentration
322
Q

Explain the mechanism by which competitive inhibition by enzymes work (3)

A

competes (with substrate) / competitive (1)
enters / fits in / binds to / blocks, active site (1)
prevents substrate from entering active site (1)
(binds to active site) temporarily (1)

323
Q

Explain the importance of species evenness in determining the biodiversity in a habitat (3)

A

measures), abundance / numbers, of individuals in each species ;
species evenness is more quantitative than species richness ;
high(er) species evenness indicates high(er) biodiversity ;oralow species evenness indicates, dominance by / high abundance of, one / few, species ;ora
used to calculate (Simpson’s) Index of Diversity ; example used to illustrate explanation of mp 3 or 4

324
Q

Suggest the implications of high Simpsons index on planning decisions (2)

A

many species present / high species richness / all species evenly represented / high species evenness / high biodiversity ;(so)

should not be developed / development should be modified / development should be reconsidered / should be conserved /

325
Q

Describe how it is possible to use selective breeding to improve the overall disease resistance of a crop (6)

A
  1. cross / breed, with disease resistant variety ;
  2. method to test offspring for disease resistance ;
  3. select , best offspring / offspring with resistance 4.(inter)breed, offspring with resistance / best offspring 5.(continue process) for (many) generations ;
  4. dea of avoid breeding, closely related / AW , individuals to preserve genetic diversity ;
  5. ora (regularly back) cross with, wild variety ;
  6. idea of preserving rare varieties in case they are needed in the future
326
Q

Describe the way in which an endothermic animal prevents body temperature decreasing (5)

A
  1. peripheral / skin ,thermoreceptors/ (heat) receptors ,stimulated (by decrease in external temp) ;
  2. (impulses sent to / blood temperature monitored in )hypothalamus / sensory cortex; vasoconstriction of , arterioles / small arteries , to reduce heat loss ;
  3. (prevents heat loss by) radiation / conduction / convection ;
  4. increased,metabolic rate / metabolism / respiration , to generate heat (energy) ;
  5. (release of) adrenaline / thyroxine ; shivering / (involuntary) muscle spasms , to generate heat (energy) ; 6.erector / hair , muscles raise , (skin) hair / fur , to trap , air / heat
  6. reduce sweating
327
Q

Explain how the structure of galactose allows it to be used as a respiratory substate (3)

A

Bonds contain energy
(bonds) can be broken by (respiratory) enzymes
soluble so , can move (within cell)
H / OH , (groups) can form H bonds with water / allow solubility