OCR B Flashcards
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 ………………… .
pituratary gland/hypotalamous
hypothalamus
cerebral cortex?
medula oblongata
Explain how fMRI measures brain activity.
Explain how fMRI measures brain activity.
Suggest two advantages of fMRI over computed tomography (CT) for the measurement of brain activity.
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
Another imaging method can identify regions of brain damage by measuring electrical activity across the brain. Name this method
ecg
Explain how the loop of Henle performs its role in the production of urine
(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
Outline how blood pressure can be measured manually
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
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
(active transport) into root hairs apoplast / symplast pathway through epidermis / cortex layers via xylem vessel to (root) nodule
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
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
outline role of crista(e) in the function of the mitochondrion.
crista(e)
large surface area, for oxidative phosphorylation / ATP production
State the importance of the intermembrane space for mitochondrial function.
establish, H+ / proton gradient, across inner membrane
1
Explain why chemiosmosis stops during apoptosis
H+ / electrochemical gradient / proton motive force, lost ATP synthase stops / ATP not produced / uncoupling of electron transport from ATP synthesis
Suggest why the electron transport chain is interrupted during apoptosis
less / loss of, cytochrome C (from intermembrane space) reduction in / loss of, electron transfer / shuttling between, complexes / carriers
Suggest why apoptosis has no effect on the oxidation of reduced NAD and reduced FAD.
(reduced NAD/reduced FAD) oxidised on inner membrane / inner membrane not affected
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
measurement of, glycosylated / glycated, haemoglobin glycosylated / glycated, haemoglobin proportional to blood glucose average measurement over several, weeks / months
Describe two pieces of lifestyle advice that a doctor may give to a patient with type 2 diabetes.
reduce sugar intake / controlled diet lose weight increase exercise participation
Give one reason why some people are concerned with increasing levels of type 2 diabetes
strain on health service ref to complications of the disease
A CT scan is more likely to detect a small lung tumour than an X-ray. Explain why
CT involves more than one X-ray CT is a 3D image CT has greater resolution / can see greater detail with CT
Outline the role of photosynthesis in the production of named molecules required for respiration.
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
suggest the advantages of using the colorimeter. for observing haemolysis
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
Suggest one adaptation that would have enabled primitive plants, such as charophytes, to evolve to living on land.
waxy cuticle (to prevent water loss) roots (for obtaining water) gas exchange structures
Why do seed-bearing plants need a transport system
large and multicellular have small SA:V idea that diffusion distance is large and diffusion is too slow to meet need
Explain the role of a ‘sink’ in the mechanism of translocation
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
Suggest one explanation for this lower heart rate.
(student) was , fitter / undertaking athletic training (student) had a higher stroke volume genetic reasons
The walls of the alveoli consist of squamous epithelial cells.
How does the structure of these cells differ from the epithelial cells lining bronchioles?
(squamous epithelial cells) do not have cilia (squamous epithelial cells) are flattened (squamous epithelial cells) have fewer mitochondria
Bronchiole walls contain smooth muscle and elastic fibres.
Describe the role of each of these tissues
smooth muscle contracts to , control / adjust / reduce lumen size
elastic fibres allow , stretch / recoil OR allow lumen to , dilate / return to usual size
smooth muscle contracts to , control / adjust / reduce lumen size
elastic fibres allow , stretch / recoil OR allow lumen to , dilate / return to usual size
(wall of) trachea OR bronchus AND support / prevents (airway) collapse
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
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
- 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.
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
) 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.
less blood (supplied to muscles) less oxygen / glucose (supplied to muscles) less (aerobic) respiration
Suggest how a faulty G2 checkpoint may affect the cell cycle.
no response to / detection of, DNA damage / AW cells division / mitosis, continues apoptosis not triggered
2
Explain how meiosis is significant in the life cycle of a plant
forms, haploid cells / gametes gametes that are genetically different / allows variation prevents doubling of the chromosome number
which parts of the PQRST show The time taken to conduct the cardiac impulse through the AV node
PR interval
which parts of the PQRST show The time taken for ventricular depolarisation and repolarisation
QT interval
which parts of the PQRST show The time taken for ventricular diastole
TP PR
which parts of the PQRST show two intervals which decrease during exercise.
RR TP QP
which parts of the PQRST show Will be elevated during or after a heart attack
ST (segment)
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.
sit person in W position
give aspirin to chew if appropriate
assist them to take any angina medication monitor pulse and breathing
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.
idea of increased reabsorption (of calcium ions) idea of more (calcium ion) transport proteins / more active transport/ more facilitated diffusion
Name two molecules other than DNA or RNA which contain a purine
ATP / ADP / AMP / NAD / NADH / FAD / FADH
Explain how the action of ADH on the cells of the collecting duct brings about changes in the concentration of urine
(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
Describe the roles of acetylcholine and other neurotransmitters in the interaction between neurones in the brain.
• 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
Which area of the brain is associated with memory?
cerebral cortex
How is oxygen transported in mammals?
idea of (reversibly) bound to haemoglobin
Name one gene present in mitochondrial DNA.
cytochrome c oxidase
