OCR B

Question 1

The symptoms of a traumatic brain injury are dependent on the region(s) of the brain
affected. Damage to ………………… may lead to the release of hormones such as ADH
and oxytocin into the blood. Damage to ………………… may cause a poor regulation of
body temperature. Motor function may be affected if there is damage to ………………… .
Brain death is confirmed if there is a permanent loss of function in ………………… .

Answer 1

pituratary gland/hypotalamous

hypothalamus

cerebral cortex?

medula oblongata

Question 2

Explain how fMRI measures brain activity.

Answer 2

Explain how fMRI measures brain activity.

Question 3

Suggest two advantages of fMRI over computed tomography (CT) for the measurement of brain activity.

Answer 3

real-time measurement / CT only gives still image  view brain activity directly  greater soft tissue detail / contrast / resolution  no need for, dyes / contrast agents  no exposure to radiation 
2

Question 4

Another imaging method can identify regions of brain damage by measuring electrical activity across the brain. Name this method

Answer 4

ecg

Question 5

Explain how the loop of Henle performs its role in the production of urine

Answer 5

(role is) to set up a range of water potential gradients between medullary tissue fluid and collecting duct  diffusion of water out of descending limb  ion concentration high at base of loop  sodium and chloride ions diffuse out of base of ascending limb  water cannot leave ascending limb / ascending limb impermeable to water  ions pumped out of upper ascending limb 

Question 6

Outline how blood pressure can be measured manually

Answer 6

any 3 from: cuff of sphygmomanometer cuts off blood flow  to brachial artery (of arm)  stethoscope used to listen to blood flow  cuff slowly relaxed / valve released  first sound indicates systolic pressure  disappearance of sound indicates diastolic pressure 

Question 7

Iron is essential for the activity of the nitrogen-fixing enzyme, nitrogenase.
Iron is present as ions in soil water but is not taken up by root nodules directly.
Describe how iron ions in soil water reach the root nodules

Answer 7

(active transport) into root hairs  apoplast / symplast pathway  through epidermis / cortex layers  via xylem vessel to (root) nodule 

Question 8

FSH is a glycoprotein.
After synthesis, the polypeptides of FSH are folded in the lumen of the endoplasmic reticulum.
Describe how FSH is processed further and then secreted from a pituitary cell

Answer 8

transported to Golgi (apparatus / body / complex)  glycosylated / sugar / carbohydrate added using glycosylase / enzymes  packaged into / formation of (secretory) vesicles  fusion of vesicles with, plasma / cell surface, membrane

Question 9

outline role of crista(e) in the function of the mitochondrion.

Answer 9

crista(e) 

large surface area, for oxidative phosphorylation / ATP production 

Question 10

State the importance of the intermembrane space for mitochondrial function.

Answer 10

establish, H+ / proton gradient, across inner membrane 

1

Question 11

Explain why chemiosmosis stops during apoptosis

Answer 11

H+ / electrochemical gradient / proton motive force, lost  ATP synthase stops / ATP not produced / uncoupling of electron transport from ATP synthesis

Question 12

Suggest why the electron transport chain is interrupted during apoptosis

Answer 12

less / loss of, cytochrome C (from intermembrane space)  reduction in / loss of, electron transfer / shuttling between, complexes / carriers

Question 13

Suggest why apoptosis has no effect on the oxidation of reduced NAD and reduced FAD.

Answer 13

(reduced NAD/reduced FAD) oxidised on inner membrane / inner membrane not affected 

Question 14

Several different blood tests are used to diagnose and manage diabetes. One test measures how well a patient’s blood glucose levels are being controlled. The patient is not required to fast beforehand. Explain how this test works

Answer 14

measurement of, glycosylated / glycated, haemoglobin  glycosylated / glycated, haemoglobin proportional to blood glucose  average measurement over several, weeks / months 

Question 15

Describe two pieces of lifestyle advice that a doctor may give to a patient with type 2 diabetes.

Answer 15

reduce sugar intake / controlled diet  lose weight  increase exercise participation

Question 16

Give one reason why some people are concerned with increasing levels of type 2 diabetes

Answer 16

strain on health service  ref to complications of the disease 

Question 17

A CT scan is more likely to detect a small lung tumour than an X-ray. Explain why

Answer 17

CT involves more than one X-ray  CT is a 3D image  CT has greater resolution / can see greater detail with CT 

Question 18

Outline the role of photosynthesis in the production of named molecules required for respiration.

Answer 18

O2
• photolysis • details of photolysis, e.g. splitting of water in photosystem II using light
Glucose • Calvin cycle • details of intermediates, e.g. production of GP (glycerate 3-phosphate), reduction of GP to TP (triose phosphate) and joining of two TP to produce glucose • requirement for ATP and NADPH (reduced NADP) in reduction of GP to TP • carbon fixation, carbon from CO2 combines with RuBP • stroma of chloroplasts • dark reaction / light-independent
ATP and NADPH • H+ ions / protons (in thylakoid space), drive chemiosmosis / drive ATP synthase / allow production of ATP • NADPH (reduced NADP) produced in stroma from NADP+ and H+ • light-dependent

Question 19

suggest the advantages of using the colorimeter. for observing haemolysis

Answer 19

colorimeter gives quantitative results 

observing haemolysis is qualitative / AW 

advantages of colorimeter takes away human subjective judgement on haemolysis / AW 

allows calibration to give concentration at which cells are isotonic with sodium chloride solution / AW 

Question 20

Suggest one adaptation that would have enabled primitive plants, such as charophytes, to evolve to living on land.

Answer 20

waxy cuticle (to prevent water loss)  roots (for obtaining water)  gas exchange structures

Question 21

Why do seed-bearing plants need a transport system

Answer 21

large and multicellular  have small SA:V  idea that diffusion distance is large and diffusion is too slow to meet need

Question 22

Explain the role of a ‘sink’ in the mechanism of translocation

Answer 22

removes sucrose from phloem  decreases hydrostatic pressure at (sink) end of sieve tube  idea that it lowers sucrose concentration because sucrose is used for respiration / metabolism  idea that sucrose removed from phloem (so) water potential increases in phloem

Question 23

Suggest one explanation for this lower heart rate.

Answer 23

(student) was , fitter / undertaking athletic training  (student) had a higher stroke volume genetic reasons 

Question 24

The walls of the alveoli consist of squamous epithelial cells.
How does the structure of these cells differ from the epithelial cells lining bronchioles?

Answer 24

(squamous epithelial cells) do not have cilia  (squamous epithelial cells) are flattened  (squamous epithelial cells) have fewer mitochondria 

Question 25

Bronchiole walls contain smooth muscle and elastic fibres.

Describe the role of each of these tissues

Answer 25

smooth muscle contracts to , control / adjust / reduce lumen size 

elastic fibres allow , stretch / recoil OR allow lumen to , dilate / return to usual size

Question 26

smooth muscle contracts to , control / adjust / reduce lumen size 

elastic fibres allow , stretch / recoil OR allow lumen to , dilate / return to usual size

Answer 26

(wall of) trachea OR bronchus AND support / prevents (airway) collapse

Question 27

Euphorbia virosa is a species of cactus that grows in the deserts of Namibia.
It uses the guard cells to close its stomata during the hottest part of the day.
Describe the sequence of events that occur inside guard cells resulting in the opening of stomata during daylight hours and suggest why the stomata of E.virosa are closed during the hottest part of the day

Answer 27

potassium ions (K+) actively transported into the (cytoplasm of the) guard cells  decreases water potential (inside cell)  water moves in, by osmosis / down water potential gradient  outer walls (of guard cells) are thinner  ORA resulting in, curved shape / AW  3 Max idea of water loss too great  transpiration would occur too quickly

Question 28

• Proteases in the small intestine of an athlete will break down proteins in sports drinks. The amino acids then enter the bloodstream and are transported to muscle cells. In the muscle cells, amino acids are used to synthesise proteins such as myosin. Explain how amino acids are transported to and taken up by muscle cells and then incorporated into proteins.

Answer 28

transport  dissolves / soluble in plasma  polar molecule  contraction of heart  details of facilitated diffusion  details of action of channel / carrier proteins  passive process  high to low concentration

formation of proteins  4 nucleotide bases  adenine, thymine, cytosine and guanine  codon and anti-codon  hydrogen bonding between bases  unzipping / breaking of hydrogen bonds  production of mRNA  formation of phosphodiester bonds between nucleotides, condensation reactions  role of tRNA  formation of peptide bonds between amino acids  complementary base pairing  details of protein structures

Question 29

) Atrial septal defect (ASD) is a condition caused when the septum of the heart has not formed correctly. This is also known as ‘a hole in the heart’ and is shown in Fig. 3.3.
In an adult with ASD, blood will leak from the left atrium into the right atrium. Suggest why the muscles of an adult with ASD will fatigue more quickly.

Answer 29

less blood (supplied to muscles)  less oxygen / glucose (supplied to muscles)  less (aerobic) respiration 

Question 30

Suggest how a faulty G2 checkpoint may affect the cell cycle.

Answer 30

no response to / detection of, DNA damage / AW  cells division / mitosis, continues  apoptosis not triggered 
2

Question 31

Explain how meiosis is significant in the life cycle of a plant

Answer 31

forms, haploid cells / gametes  gametes that are genetically different / allows variation  prevents doubling of the chromosome number

Question 32

which parts of the PQRST show The time taken to conduct the cardiac impulse through the AV node

Answer 32

PR interval

Question 33

which parts of the PQRST show The time taken for ventricular depolarisation and repolarisation

Answer 33

QT interval

Question 34

which parts of the PQRST show The time taken for ventricular diastole

Answer 34

TP  PR

Question 35

which parts of the PQRST show two intervals which decrease during exercise.

Answer 35

RR  TP  QP 

Question 36

which parts of the PQRST show Will be elevated during or after a heart attack

Answer 36

ST (segment)

Question 37

The chances of surviving and recovering from a heart attack can be increased if first aid is provided quickly.
In addition to calling 999 and informing ambulance control that a heart attack is suspected, outline the procedure a first aider should perform to assist someone having a heart attack.

Answer 37

sit person in W position 
give aspirin to chew if appropriate 

assist them to take any angina medication  monitor pulse and breathing 

Question 38

Suggest how changes in the proximal convoluted tubule in the kidney might result in an increase in the concentration of calcium ions in blood plasma.

Answer 38

idea of increased reabsorption (of calcium ions)  idea of more (calcium ion) transport proteins / more active transport/ more facilitated diffusion

Question 39

Name two molecules other than DNA or RNA which contain a purine

Answer 39

ATP / ADP / AMP / NAD / NADH / FAD / FADH

Question 40

Explain how the action of ADH on the cells of the collecting duct brings about changes in the concentration of urine

Answer 40

(ADH) binds to receptors on cell surface membrane  (leading to) increase in concentration of cAMP  idea that (cAMP) causes vesicles containing aquaporins to move  idea that aquaporins / AW, increase in cell surface membrane lining the lumen  (more) water is reabsorbed and concentration (of urine) increases  detail of action of cAMP 
max

Question 41

Describe the roles of acetylcholine and other neurotransmitters in the interaction between neurones in the brain.

Answer 41

• named excitatory neurotransmitter e.g. acetylcholine, glutamate • named inhibitory neurotransmitter e.g. GABA • neurones interact at synapses • formation of new synapses linked to memory • neurotransmitter released from pre-synaptic membrane by exocytosis • neurotransmitter released following arrival of action potential in pre-synaptic neurone • entry of calcium ions causes vesicles containing neurotransmitter to fuse with presynaptic membrane • neurotransmitter diffuses across the synaptic cleft • neurotransmitter binds to complementary receptor on post synaptic membrane • (excitatory) results in opening of (ligand or chemical gated) sodium ion channels • sodium ions enter post synaptic neurone
post synaptic membrane depolarised (inhibitory) causes potassium ions to leave post-synaptic neurone • (inhibitory) causes chloride ions to enter post synaptic neurone • (inhibitory) hyper-polarises the post-synaptic membrane (becomes more negative

Question 42

Which area of the brain is associated with memory?

Answer 42

cerebral cortex 

Question 43

How is oxygen transported in mammals?

Answer 43

idea of (reversibly) bound to haemoglobin 

Question 44

Name one gene present in mitochondrial DNA.

Answer 44

cytochrome c oxidase 