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1
Q

What are the advantages of using insulin produced by genetically modified bacteria compared with using other sources of insulin?

A

No ethical/ animal welfare concerns
It is human insulin- less likely to cause a reaction in the immune system or cause an allergic reaction
Can be mass produced in large quantities in a small amount of time

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2
Q

What is the benefit of using stem cell therapy over insulin injections?

A

Stem cells will differentiate into beta cells which will produce insulin- will be a permanent cure so no need for insulin injections

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3
Q

Why does the concentration of
i) ions
ii) oxyhaemoglobin
decrease in the renal vein compared to the renal artery

A

The concentration of ions are adjusted based on the needs of the body, therefore some are excreted

Some oxygen is used by the kidney cells for aerobic respiration

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4
Q

How do diuretic drugs decrease blood pressure?

A

Decrease the volume of the blood
Decreases the reabsorption of water from the collecting duct back into the blood
Reducing the amount of ADH released from the pituitary gland
Reducing the amount of ions reabsorbed into the bloodstream

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5
Q

What is the function of the sodium potassium pump?

A

Pumps 3 Na+ ions out of the cell for every 2 K+ ions in the cell

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6
Q

What is the action of adrenaline in the liver

A

Binds to receptor on the cell surface membrane of the liver
The enzyme adenylyl cyclase is activated, which converts ATP to cAMP
cAMP acts as a second messenger- activating protein kinases and converting glycogen to glucose

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7
Q

What are the effectors in the skin that are involved with temperature regulation?

A

Erector muscles
Smooth muscle in the walls of the arterioles
Sweat glands

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8
Q

What are ways in which an ecosystem can change over time?

A

Succession
Human activity- mining, deforestation
Climate change changing habitats
Fluctuating population size of an organism- migration/ immigration
Evolution/ speciation

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9
Q

Why are giant tortoises able to survive without food for longer periods of time than mammals?

A

They are ectotherms- less energy used in maintaining their internal environment
Less movement/ respiration

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10
Q

What new pieces of evidence can be used to classify organisms?

A

DNA sequencing
Amino acid/ protein sequencing

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11
Q

Two control variables in a plant experiment

A

Temperature- can affect enzyme activity
CO2 conc, light intensity. light wavelength- limiting factor in the light dependant reaction
Water availability

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12
Q

How can grazing on vegetation decrease biodiversity in a habitat?

A

Overgrazing can lead to more interspecific competition for food resources

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13
Q

Why does a rabbit population increase even after introducing a virus?

A

Rabbits develop resistance to the virus, so more rabbits become immune
Carrying capacity is not reached as space, prey is not limiting

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14
Q

What indicates that an immunological response to a pathogen has taken place inside the body?

A

Antibodies in the bloodstream

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15
Q

Compare and contrast continuous and batch culture

A

Similarities- both require aseptic technique
Industrial scale reactions
Require a fermenter
Need to control temperature and pH

Continuous- nutrients added and products removed continuously
only primary metabolites produced
exponential/ log phase maintained
more problems for contamination

Batch- nutrients added once and products removed once at the end
secondary metabolites
death phase occurs

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16
Q

Describe the stages of tissue culture

A

Take an explant from a plant
Sterilise with ethanol
Place explant in a nutrient growth medium
A callus is formed (a mass of undifferentiated, totipotent cells)
Auxin and cytokine promote mitosis
Transfer to a greenhouse environment

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17
Q

Why can two twins not be “carbon copies” of one another

A

Nutrition/ malnutrition
Somatic cell mutation

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18
Q

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

A

B cells have an antibody on their surface which is complementary to one type of antigen
The selected B cell divides by mitosis into plasma cells
Plasma cells secrete antibodies which are complementary to the antigen

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19
Q

What are the properties of a bacterium

A

No membrane bound organelles
Contains a cell wall

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20
Q

Explain why toxins produced by the different strains are described as being “immunologically distinct” and how they are dealt with by the immune system

A

Toxins produced by each strain are slightly different, with slightly different 3D shapes
Immune response depends on the shape of the antigen (which in this case is the toxin)

Antigen presenting cells ingest the pathogen and present the antigens on their MHC
Interaction between APC and T helper cell produces interleukins
B cell activated- clonal expansion- differentiate into plasma cells- dividing into antibodies
Antibodies bind to and neutralise toxins

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21
Q

How do both genes and the environment cause animals to vary in their immune response?

A

Genes:
Inherit genes that code for antibodies from our parents, eg B and T lymphocytes
Autoimmune disease can also be inherited, eg rheumatoid arthiritis and lupus
Mutation can produce new alleles, coding for different antibodies

Environment:
Exposure to different pathogens determines the immune response
Vaccinations
Poor nutrition can affect the immune system
Environmental influences on allergies

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22
Q

Describe the precautions taken in the potometer experiment

A

Cut and insert the stem under water so that no air bubbles to the stem/ xylem get in and block the xylem
Take care not go get water onto the leaves
Apparatus under water
Use syringe to move bubble
All joints must be sealed with petroleum jelly so any water loss is as a result of transpiration
Keep the shoot supported to avoid breaking the water column

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23
Q

What are the functions of the cytoskeleton

A

Mechanical support
Maintains shape
Movement of organelles within the cell
Movement of flagella/ cillia
Exo/ endocytosis

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24
Q

How can we use a microscope to measure the diameter of the nucleus of a WBC?

A

Using an eyepiece graticule
Calibrate with a stage micrometer to calculate the length of one epu
Measure diameter of nucleus in epu
Take repeat measurements to calculate a mean

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25
Name the colours and image given by SEM TEM Laser scanning confocal microscope
SEM- 3d black and while TEM- 2d black and white Laser scanning confocal- 3d/2d colour
26
Name the enzyme that breaks down histone protein associated with DNA
Protease
27
Why does the the trace go downwards when using a spirometer?
The volume of air in the gas chamber decreases as the exhaled carbon dioxide is absorbed by soda lime
28
Explain why using standard deviation error bars would increase the confidence in any conclusion made.
Standard deviation shows the spread of data around the mean And reduces the effect of extreme results/ an anomoly
29
Explain the importance of maintaining biodiversity for the discovery of new antibiotics
Many drugs are origniated from plants/ bacterium If these plants go extinct, we will not be able to use it for medicinal advantages Maintaining biodiversity increases the chance of developing new drugs
30
Synthetic Biology Personalised medicine
SB- synthesis of new genes/ organisms PM- development of drugs linked to genes/ individual
31
Choose and describe a sampling technique which would show the distribution and abundance of native and introduced grasses
Lay a string in a line across the two zones Use a belt transect and a quadrat, place the quadrat at set intervals along the tape Use a key to identify the species present Estimate the percentage cover/ species frequency Repeat the experiment again, after a certain amount of time
32
Describe the similarities and differences between ultrafiltration and the formation of tissue fluid
Both occur in the capillaries Both retain larger molecules, eg proteins which are too large to be filtered High hydrostatic pressure, which is greater than oncotic pressure Molecules that are not reabsorbed by capillaries in ultrafiltration form urine, but they form lymph for tissue fluid Blood filtered through glomerulus, basement membrane, podocytes, but only through capillaries for tissue fluid Tissue fluid enters intracellular spaces whereas filtrate enters bowmans capsule, then the PCT
33
How can allele B inhibit the expression of allele A
B codes for a repressor protein, which can bind to the promoter of A and stop the translation of A
34
State developments which have led to an increase in the speed at which DNA can be sequenced
Nanopore technology Next generation sequencing Massive parallel sequencing High throughput sequencing Whole genome sequencing
35
Name the enzyme that can be used to convert mRNA to single stranded DNA
Reverse transcriptase
36
hcG mode of action as a non lipid soluble hormone
Binds to receptor on the cell surface membrane Involved in cell signalling Activates a second messenger to bring about a response in the cell.
37
How does NAD act as a coenzymes in respiration?
NAD- oxidises triose bisphosphate to form pyruvate oxidises pyruvate to form acetyl group oxidises intermediates in the Krebs cycle Addition of electrons to the electron transport chain Reduction of pyruvate to lactate in lactate fermentation Reduction of ethanal to ethanol in alcoholic fermentation
38
What type of cell makes up cambium tissue?
Meristem
39
Describe extracellular digestion?
Digestion is not occurring within the cell, enzymes are released within to the extracellular space
40
Describe the adaptations of hydrophytes
Air spaces within the leaf, to allow the leaf to float to access light for photosynthesis Stomata on upper surface of leaf to allow access to Co2 Reduced roots as they are not needed to get water
41
What are the disaccharides sucrose and lactose made of?
Sucrose- glucose and fructose Lactose- glucose and galactose
42
Explain how the failure of control mechanisms of Hox genes during development can lead to deformities?
Normally, hox genes code for transcription factors which control development of the body plan In this case, the hox gene does not produce the transcription factor Molecules signalling apoptosis/ mitosis are not produced so it does not occur.
43
Describe post- transcriptional control
Primary mRNA can be turned in mature mRNA by intron splicing Alternative splicing can produce different versions of mRNA
44
Describe the composition of the artery and vein
Artery: Thick elastic layer helps them to withstand the force of the high pressure blood Stretch and recoil Even out surges of blood from the pumping of heart Collagen for structural support and maintaining shape Smooth muscle contracts and relaxes to alter the diameter of the lumen Provides strength to withstand high blood pressure Veins: Valves to prevent the backflow of blood as blood is travelling at a low pressure, against gravity Less elastic layer as there is no pulse in the blood More collagen than arteries to give structural support as they carry larger volumes of blood
45
Outline the structures and adaptations involved in the mammalian gas exchange system
Nasal cavity- good blood supply and moist surfaces so it warms the incoming air to the temperature and humidity of the air already in the trachea, reduce evaporation Hairs and mucus secreting cells trap dust/ microbes Trachea- C shaped rings of cartilage so it does not collapse Goblet cells and ciliated epithelial cells Bronchi and bronchioles have smooth muscle which allows air to move in and out Alveoli+ adaptations
46
What properties of the mitochondrial inner membrane allow chemiosmosis to occur?
Large surface area Contains enzymes such as ATP synthase
47
Outline the importance of junctions between neurones in the functioning of the nervous system
Allows for nervous impulses to be unidirectional Allows for summation Ensures that only stimulation that is strong enough will be passed on (filters out low level stimulation)
48
Outline the importance of junctions between neurones in the functioning of the nervous system
Allows for nervous impulses to be unidirectional Allows for summation Ensures that only stimulation that is strong enough will be passed on (filters out low level stimulation)
49
Why may measuring Co2 uptake give a better indication of photosynthetic activity than oxygen production
O2 production- only gives indication of the rate of photolysis Co2 uptake- only gives indication of rate of calvin cycle
50
A weedkiller binds with electrons in photosystem I Suggest how this results in the death of a plant
Prevents cyclic and non- cyclic photophosphorylation from occurring Less ATP/ NADPH produced for the light independent stage (conversion of GP to TP)
51
Why is it important to maintain viable wild populations of crop plant species?
To bring in genetic variation into the population Acts as a gene bank, a source of useful alleles Can be cross bred with the plants to prevent an inbreeding depression Source of replacement To increase genetic diversity as a monoculture of plants will all be susceptible to the same disease etc
52
Why can a genetic bottleneck lead to low genetic diversity?
Many alleles are lost when the population is dropped Modern population descends from a small number of survivors
53
Outline how an animal can evolve into a different species when the island is separated
Allopatric speciation The animal now faces a DIFFERENT selection pressure to the animals on the mainland Mutation occur Animals with the mutation survive and reproduce and pass the beneficial allele onto their offspring
54
State 3 conditions required for speciation to occur
Speciation- the formation of a new species Time DIFFERENT selection pressure from the other population Mutation
55
How can succession be deflected?
Grazing sheep Burning patches of heather Rotational coppicing
56
Explain how properties relating to the density of water contribute to the survival of organisms
Ice is less dense than water so it can float and provide a habitat to some species Floating of ice insulates the water underneath Organisms can float in water
57
How can tourists lead to an increase in the biodiversity of an area
Ecotourism Money from tourism is used to support conservation, eg maintaining footpath, planting trees, wildlife rangers
58
How can timber be produced sustainably with felling
Limit size of area felled to minimise soil erosion Minimum distance between replanted trees to reduce competition Replant trees that have been felled
59
What are the benefits of coppicing?
Lifespan of the tree is extended Fewer large trees means more light can reach the floor, to smaller organisms Prevents succession Prevents soil erosion as the roots remain- maintain the quality of the soil Large machinery needed
60
How can biodiversity be considered at different levels?
Species richness/ species diversity- which is represented by the Simpsons index of biodiversity Habitat diversity
61
How can biodiversity be considered at different levels?
Species richness/ species diversity- which is represented by the Simpsons index of biodiversity Habitat diversity
62
Describe how to clone a plant by taking a cutting
Cut shoot from a healthy plant Cut with a slant Between nodes Dip in rooting powder
63
What observation is explained by the competitive exclusion principle?
Only one species can occupy a particular niche
64
What is the function of cholesterol within the cell membrane
Cholesterol has a hydrophilic and hydrophobic end, interacting with different parts of the phospholipid bilayer Adds stability Prevent the membrane from becoming too solid as the phospholipid molecules cannot get too close together
65
Which feature is common to bacteria, protocists and fungus?
Ribosomes
66
What is the correct definition for precision and accuracy
Precision- results have a small standard deviation Accuracy- mean result is close together
67
Why is glucose required for the contraction of skeletal muscle?
Glucose RELEASES energy to produce ATP ATP is needed to break the cross- bridges between actin and myosin ATP is hydrolysed into ADP and Pi to reset the myosin heads
68
Describe the vascular bundle in a: Root Leaf Stem
Stem: Xylem on inside, phloem on outside Root: X shape xylem in middle, with phloem surrounding Leaf- long with a dip, xylem on top, phloem on bottom
69
Describe the vascular bundle in a: Root Leaf Stem
Stem: Xylem on inside, phloem on outside Root: X shape xylem in middle, with phloem surrounding Leaf- long with a dip, xylem on top, phloem on bottom
70
Why is only a small amount of body mass made of ATP
ATP is hydrolysed into ADP Immediately made and used Used for active transport, growth etc
71
Define: Resolution Random error Systematic error
Resolution- measuring instruments having smaller divisions so can measure smaller changes Systematic error- consistent repeatable errors involving equipment Random error- always present when taking readings but can be overcome by doing repeats and a mean
72
Describe the synaptic pathway
Arrival of action potential in the pre synaptic neurone causes opening of Ca2+ ion channels Stimulates release of neurotransmitter by exocytosis Neurotransmitter causes Na+ ion channels to open in the post synaptic neurone
73
What is the supply of blood in the liver?
Hepatic portal vein- deoxygenated blood with nutrients from the small intestine Hepatic artery- oxygenated blood
74
Suggest two ways in which the ultrastructure of a chloroplast can be affected by high temperatures
Damage to chlorophyll reduce the light dependant reaction Damage to the membranes of the chloroplast Damage ETC/ ATP synthase which will result in less ATP being made in the LDR
75
Why can athletes expend so much energy without needing to carry out aerobic respiration?
Cells can tolerate lower pH levels Phosphocreatine stores/ stores of ATP
76
What is the role of pyruvate in anaerobic respiration?
It acts as a hydrogen acceptor, accepting H from NADH so NAD can be generated so that glycolysis can continue and some ATP can still be made
77
Why does aerobic respiration yield fewer molecules of ATP than the theoretical maximum?
Some ATP is needed to actively transport pyruvate into the mitochondrion Some H+ ions may leak back through into the matrix Not all the NADH is used in respiration
78
Why does anaerobic respiration produce less ATP than aerobic?
No oxygen available as the final electron acceptor No chemiosmosis Only glycolysis can occur- glucose made into pyruvate w net gain 2 ATP Substrate level occuring only- not oxidative phosphorylation
79
What is the difference between peritoneal and haemodialysis ?
Haemodialysis uses a counter current flow so that a steep concentration gradient is maintained Therefore, it is more effective at removing waste than peritoneal dialysis
80
What do large error bars that overlap indicate?
Overlapping- no significant difference between the two sets of data Large- large random error in the results
81
What is the Bohr effect?
Haemoglobins affinity for oxygen is reduced, so that oxygen can dissociate from haemoglobin more easily. More can be supplied to muscles, for aerobic respiration Curve shifts to the right
82
What processes occur during prophase?
Chromatin coils and condenses to become visible Spindle fibres form Centrioles migrate to opposite ends of the cell Nuclear envelope breaks down In meiosis only: 2 prophases In prophase 1- homologous chromosomes pair and bivalents form Crossing over occurs and chiasmata form

Past paper questions (1 decks)

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