Module 3 Flashcards
The changes in blood pressure in the right atrium are the same as those in the left atrium. The changes in blood pressure in the right ventricle are different from those in the left ventricle.
(both) atria pump blood to ventricles ; same / short, distance ;
right ventricle pumps blood to lungs ; short distance / at low(er) pressure / at approx 3.2 kPa / at approx 24 mmHg ; ora i.e. (left ventricle) greater distance / high(er) pressure / at approx 15.8 kPa / at approx 120 mmHg less resistance, in lungs or pulmonary circulation / greater resistance in the systemic circulation ; left ventricle pumps to, whole body / AW ; correct ref. to (muscular) walls ; e.g. same (thickness) in atria thicker / thinner, in ventricles more / less, muscular, in ventricles right ventricle pumps with lower / less, force ; ora
Some components of tobacco smoke are absorbed into the blood stream and affect the cardiovascular system.
Describe the effects of nicotine on the cardiovascular system
nicotine increases heart rate ; increases blood pressure ; makes platelets ‘sticky’ ; increases chance of blood clotting / promotes thrombosis ; decreases flow of blood to, extremities / AW ; constriction of blood vessels
Some components of tobacco smoke are absorbed into the blood stream and affect the cardiovascular system.
Describe the effects of nicotine on the cardiovascular system
carbon monoxide combines with haemoglobin / forms carboxyhaemoglobin / higher affinity for haemoglobin (than oxygen); R absorbed, reacts with, bonds to reduces oxygen carrying capacity (in context of, haemoglobin / blood) ; promotes release of damaging free radicals / peroxides / super oxides / oxidising agents ; causes platelets and neutrophils to stick together / platelets to stick to endothelium ; hypoxia can damage heart muscl
Describe the roles of centrioles in animal cells.
(during), mitosis / meiosis / nuclear division ; ignore ‘cell division’ / phases replicate, after / before, each division ; A at interphase move / separate, to poles ; assemble / organise, microtubules ; centre for growth of / forms, spindle fibres / for formation of spindle / AW ; modified centrioles found elsewhere such as in flagella / cilia ;
) Explain why it is possible to see the internal membranes of a cell in electron micrographs, such as Fig. 2.1, but it is not possible to see them when using the light microscope.
(EM has) greater / higher, resolution / resolving power ; ora explanation of resolution as ability to differentiate between two points (close together) ; width of membranes is 7 nm (±1) ; (resolution of) LM is 200 nm (0.2 µm) and EM is 0.5 nm (0.0005 µm) ; A 0.5 to 1 nm (0.001 µm) ref to shorter wavelength ; ora resolution is equal to half the wavelength ;
explain the effect of increasing temperature on the beetroot tissue.
at (temperatures above) 60 °C, cell / vacuolar, membranes damaged / AW; A tonoplast (membrane ) proteins, denatured / altered tertiary structure ; increased fluidity (of membrane) / phospholipid bilayer more fluid ; (so) diffusion / AW, of, betalain / pigment (out) ; as temperature increases, rate of diffusion increases / diffusion occurs more quickly
structure of collagen
more than four (different) monomers (monomers =) amino acids / polypeptides no sugar no base(s) strands not antiparallel peptide bonds no phosphate / phosphorus A sulfur (sulphur) present left handed helix tightly coiled triple helix A three stands
structure of dna
4 (different) monomers (monomers =) nucleotides / polynucleotides double helix right handed helix loose helix sugar antiparallel strands phosphodiester bonds base(s) phosphate / phosphorus
State what is meant by the term tidal volume.
volume of air breathed, in / out, with one breath
Explain how the minute volume at rest would be determined
before / after recovery from, exercise ;
either measure tidal volume, by breathing out into a bag ; multiply by number of breaths per minute ; A total tidal volume in x minutes ÷ x
or use a spirometer / described ; ref to taking recordings from a trace / use of a, kymograph / datalogger
Suggest two differences in the structure of the lungs that may account for the greater oxygen uptake by people who live on top of mountains
(bigger lungs so) more alveoli ; A greater surface area (of alveoli) more, bronchioles / airways ; R more bronchi wider, bronchioles / airways ; larger number / higher density, of capillaries (around alveoli) ; thinner wall / shorter distance, between air and blood / AW ;
Explain why the red blood cell count increases so much when people visit places at high altitude.
partial pressure of oxygen is low ; A low concentration of oxygen / less oxygen more haemoglobin (is required / produced / synthesised / available) ; compensates for smaller volume of oxygen absorbed / compensates for lower saturation of haemoglobin / more oxygen can be carried (per unit of blood) ; ref to, EPO / erythropoeitin ;
Suggest how organisms that live in freshwater that has a low concentration of sodium ions. and who’s body fluids have a higher concentration of sodium ions than the surrounding water, retains sodium ions in its body fluids.
cell membranes impermeable to sodium ions ; (as) sodium ion channels are not present (in cell membranes) ; active transport / active uptake ; A sodium pumps to take up sodium ions move sodium ions against their concentration gradient ; uses, energy / ATP ;
State one role of sodium ions in organisms.
ref. to, (nerve) impulses / action potentials / depolarisation / resting potential ; treat ref. to electric as neutral helps to maintain, water / solute / osmotic, potential of, body fluids / named body fluid ; helps to maintain, osmotic / electrolyte, balance ; ref. to, urine formation / osmoregulation ; absorption of glucose / co-transport ; [1 max]
flatworm which lives in ponds, streams and rivers. The dimensions of the flatworm are 12.5 mm long by 3.0 mm wide. Its volume was estimated as 12.6 mm3. Flatworms do not have a transport system for the respiratory gases, oxygen and carbon dioxide.
explain how flatworms survive without a transport system for respiratory gases.
thin / flat ; large / high, surface area to volume ratio / small / low, volume to surface area ratio ; R large surface area (on its own) (SA:V ratio) 5.95:1 ; A anything between 5:1 and 7:1 or suitable calculation e.g. 2 × (12.5 × 3.0) / 12.6
state two ways in which the structure of catalase is similar to the structure of haemoglobin and one way in which it differs
similarities
made of amino acids / amino acid monomers / polymer of amino acids A protein / polypeptides have quaternary structure / have more than one polypeptide chain ; four, sub-units / polypeptides ; haem / porphyrin / prosthetic group(s) ; [2 max]
difference
(four) sub-units / polypeptides, are identical ; or haemoglobin has, two different, sub-units / polypeptides ; or haemoglobin has alpha and beta polypeptides ;
(catalase) has active site(s) ; A Hb has (oxygen) binding site
State why it is possible for a catalase molecule to bind to four substrate molecules at the same time.
each, sub-unit / polypeptide, has an active site ; catalase has four, active sites / haem groups ;
Explain, in terms of water potential, how water moves from across the leaf
water moves down water potential gradient ; A high(er) to low(er) water potential / less negative to more negative water potential apoplast pathway / through cell walls ; symplast pathway / through, plasmodesmata / cytoplasm ; evaporation ; from spongy mesophyll cell walls ; into (substomatal / intercellular) air space ; diffusion of water vapour ; A diffusion of water if evaporation used in correct context elsewhere through stomata ;
State and explain three ways in which the structure of xylem vessels is adapted to transport water.
cellulose, cell wall / lining ; allows adhesion of water ; and prevents collapse providing support under tension
either lignin ; waterproofing / prevents water loss ; or lignin ; A rings / spirals / thickening / AW (of walls) prevents collapse / idea of providing support (under tension) ;
no cytoplasm / lack of contents / hollow / empty lumen ; R dead less resistance to / unimpeded / uninterrupted / unhindered / ease of / AW, flow / AW ; A greater volume per unit time / faster rate R continuous, smooth
lack of end walls / continuous tube ; less resistance to / unimpeded / uninterrupted / unhindered / ease of / AW, flow / AW ; R continuous, smooth
pits / pores ; R holes lateral movement / movement around air bubbles / supplies (water) to (surrounding), cells / tissues ;
wide / large diameter / large lumen ; so large volume of water can be transported ;
how do you know a cell is in metaphase
chromosomes / chromatids, on equatorial plate / at equator / AW ; A in, centre / middle, of cell nuclear, membrane / envelope, dispersing / breaking up / (partially) visible / AW ; A disappearing chromosomes, in one group / not in two groups / not arrow shaped / not going to poles / not separated / AW ;
Describe how cigarette smoke is responsible for the development of lung cancer.
smoke / tar, is carcinogenic
genes control, cell division / mitosis ;
mutation / change to DNA (in these genes) ;
tumour suppressor genes switched off cells,
uncontrolled mitosis
cancer cells do not respond to signals ;
(and) form a (malignant) tumour ;
(tar) settles on bronchial, epithelial cells / epithelium ;
State and explain two ways in which the structure of a phloem sieve tube is adapted for the transport of assimilates.
sieve pores ; allow easy flow (from sieve tube element to sieve tube element) ; R flow of water
sieve plate ; (may) prevent sieve tubes from bursting / AW ;
cell (surface) membrane / plasma membrane ; prevents loss, of sucrose / assimilates / phloem sap ; little cell contents / AW ; R no cell contents little resistance / AW, to flow ; R flow of water
plasmodesmata ; allows flow, to / from, companion cells ;
thin walls ; for, rapid / easy, entry of water (at source, to build up pressure)
Describe the function of the endodermis in roots.
Casparian strip / suberin, is impermeable (to water) ; blocks, apoplast pathway / pathway between cells / cell wall pathway ; ref. to passage cells ; water / (inorganic) solutes / minerals / ions, must pass through, endodermal cells / symplast pathway / symplast pathway described ; cell can select solutes / AW ; ref. to, active transport / carrier proteins ; ref. to presence of solutes (at base of xylem) causing increase in root pressure / AW
State two roles of water within plant cells other than taking part in breakdown reactions
accept any two relevant examples, e.g.
solvent / medium for reactions ;
transport medium ;
maintaining turgidity / keeping firm / prevents flaccidity / AW ;
(raw material / reactant for) photosynthesis / photolysis ;
expansion / elongation / growth ;
maintains, hydrostatic pressure / pressure potential ;
maintains water potential (gradient) ;
A maintains osmotic gradient / prevents plasmolysis
stomatal opening ;
hydrophilic interactions of membranes ;
(in vacuole) pushes chloroplast to edge of cell ;
R hydrogen bonding unqualified by ref. to membranes
Describe the role of elastic fibres in the wall of the alveolus
stretch / expand / lengthen, on inspiration and, recoil / shorten, on expiration ;
A alternatives for inspiration and expiration but R contract and relax
(stretch) to increase, surface area / volume of air, for, diffusion / gas exchange ;
(recoil) to (help), expel air / force air out ;
explain how alveoli are adapted for gas exchange.
correct ref. to diffusion of, carbon dioxide / oxygen ; A absorb / lose / AW
(many alveoli) large surface area ;
surrounded by, (many) capillaries / capillary network / AW ;
short diffusion distance (between air and blood) ;
blood maintains concentration gradient ;
epithelium / alveolar wall / AW, thin / squamous ; A alveolus one cell thick
A alveolus has a thin wall
R cell wall e.g. alveolar cell wall is thin
idea that very little between, epithelium and endothelium / AW ;
e.g. alveolus and capillary are close together
State two ways in which the lung tissue of someone with emphysema differs from the lung tissue of someone with healthy lungs.
assume answers are about person with emphysema, accept ora if clear
fewer alveoli / (large) ‘holes’ ;
A alveolar walls broken down / fewer air sacs / alveoli burst / destroyed
less / destroyed / broken, elastic tissue / elastin ; ignore damaged
R no, elastin / elastic fibres
small(er) surface area ;
fewer capillaries ;
named change(s) to bronchial tissue ; e.g. enlarged goblet cells, more mucus, scar
tissue, scarred, narrow lumen in airways, inflammation, damaged / no, cilia
ref. to tar deposits ;
State two symptoms of emphysema
shortness of breath (when exercising) / breathlessness ;
A breathing difficulty
wheezing / AW (on inspiration) ;
rapid breathing rate / hyperventilation / decreased ability to hold breath ;
R heavy breathing
chest, tightness / pain ;
cyanosis / bluish appearance to the skin / AW ; A pale
fatigue / tiredness / lethargy / weakness / dizziness / AW ;
coughing / coughing up blood ;
lots of mucus produced / much phlegm ;
expanded / barrel, chest ;
Explain how the valves ensure one-way flow of blood through the heart.
allow ref to one side only valve opens to allow blood from atria to ventricles ;
when ventricles contract, valves close (to stop backflow) ;
A valves close when blood is pumped out of the ventricles
ref. to pressure difference between chambers ;
Explain the roles of the sinoatrial node (SAN), atrioventricular node (AVN) and the Purkyne tissue during one heart beat.
SAN sends out, wave of excitation / impulses ; A electrical (im)pulses
R once only - nervous impulse(s) / pulse(s) / signal(s) / wave(s)
R if brain stimulates SAN to send out impulses
2 spreads across atria ;
3 atria contract / atrial systole ;
4 fibrous ring / non-conducting tissue / insulating tissue ;
5 prevents, it reaching the ventricles / ventricles contracting at the same time (as atria) ;
6 AVN sends on wave of excitation to ventricles ;
A in context – impulse reaches AVN and is passed on to ventricles
7 (therefore) time delay to allow, atria to empty / atria to complete contraction / ventricles
to fill / atria and ventricles do not contract at the same time ;
8 time ref. 0.1–0.2 seconds ;
9 Purkyne tissue conducts, excitation / impulses, to base of, septum / ventricles ;
A apex of heart
10 spreads upwards in ventricle (walls) ;
11 (so) ventricles contract from base upwards / ventricles force blood up from base ;
State two ways in which the composition of blood entering the right atrium is different to blood entering the left atrium.
right atrium has (ora for left atrium)
lower, concentration/partial pressure/AW, of, oxygen ; R no oxygen
A (right) deoxygenated blood (versus oxygenated blood)
A higher saturation of haemoglobin with oxygen
higher concentration/AW of, hydrogen carbonate ions/carbon dioxide ;
A more carbaminohaemoglobin
higher concentration of water molecules/high(er) water potential/less negative water
potential ;
higher concentration/AW, of glucose ;
patent ductus arteriosus – a link between the pulmonary artery and aorta fails to close after birth
Suggest and explain how the flow of blood in a person with patent ductus arteriosus differs from that of a person with a healthy heart.
suggest
1 blood flows from aorta to pulmonary artery ;
2 increased volume of / more, blood to lungs ;
A blood to lungs at higher pressure
3 oxygenated and deoxygenated mix ;
4 oxygenated blood / blood from aorta, to lungs ;
explain (why blood flows from aorta to pulmonary artery)
5 left ventricle thicker wall (than right ventricle) ;
6 (so) contraction generates greater force (than right ventricle)/AW ;
7 higher pressure in aorta (than pulmonary artery)
Explain the role of goblet cells in the maintenance of a healthy gas exchange system
synthesise/produce/secrete/release, mucus ;
mucus, sticky/AW ;
(mucus) traps/AW, pathogens/AW , dust/particles/AW, pollen ;
A named organism types/microorganisms
R cilia traps
increased secretion when, inflamed / infection ;
qualified ref. to role of mucus ; e.g.
increases distance (e.g. of pathogen) to reach (epithelial) cells
acts as barrier/prevents, entry/attachment to, cells
prevent, infections/pathogens reaching alveoli
Explain the role of cilia in the maintenance of a healthy gas exchange system
waft/move/AW, mucus ;
synchronous/metachronal, rhythm ; AW
movement towards back of throat for, swallowing/coughing out ;
qualified ref. to role of cilia in health ; e.g. ref. to, normal air flow/ventilation/keeping airways
clear
why is left ventricle s wall thicker than the right ventricle
(Y/wall of left ventricle) contains more (cardiac) muscle ; ora
left ventricle/ventricle beside Y, pumps blood to, whole body / further ; ora
at higher pressure with more force (than right) ; ora
resistance to blood flow is greater in systemic circulation ;
Name the medical condition caused by breakdown of the elastic fibres
(ii) emphysema
Cigarette smoke contains tar, a substance which has several harmful effects on the cells lining the gas exchange system.
Outline three of these effects.
(cause) mutations ;
uncontrollable, division/mitosis/cell replication/cell growth ;
lack of contact inhibition/no apoptosis or described/(proto)oncogenes ;
goblet cells secrete, excess/more/AW, mucus ;
destroys/weakens/paralyses/AW, cilia ;
development of scar tissue ;
inflammation ;
increased chance of infection/AW
Explain the importance of the effect of carbon dioxide on haemoglobin
carbon dioxide influences percentage saturation of haemoglobin with oxygen / AW ;
2 tissues / cells, with high rate of (aerobic) respiration ;
3 high demand for oxygen ;
4 haemoglobin / blood, releases more oxygen ; R faster
5 than it would in absence of carbon dioxide ;
6 at same partial pressure of oxygen ;
The percentage saturation of haemoglobin with oxygen decreases as the partial pressure of carbon dioxide increases.
Explain how this happens
either
react or combine with haemoglobin / form haemoglobinic acid / form HHb ;
A ‘picks up’ / absorb
or
carbon dioxide combines with haemoglobin / forms carboxyhaemoglobin ;
(so) stimulate haemoglobin to release more oxygen (in areas of low pO2) ;
ref. to, allosteric effect / change in tertiary or quaternary structure or shape ;
A conformational change
either
haemoglobin has a higher affinity for hydrogen ions than oxygen = 2 marks
or
haemoglobin has a higher affinity for carbon dioxide than oxygen = 2 mar
role and importance of carbonic anhydrase
(catalyses very) fast / AW, reaction ;
(carbon dioxide as) hydrogen carbonate ions / bicarbonate ions ;
diffuse / move / leaves, out of the (red blood) cell ;
in(to) the plasma ; R ‘into blood’
(so that) blood can transport more than could be transported as carbon dioxide (in
solution) / 80 – 90% CO2 transported this way ;
idea that
reaction maintains concentration gradient for CO2 from, tissues / tissue fluid, to blood ;
if carbon dioxide transported then pH would decrease ;
(therefore) maintains pH / prevents pH decreasing / acts as a buffer ;
State three ways in which the blood at venules differs from the blood at the artefioles other than in the concentration of carbon dioxide.
assume answer refers to Y unless told that it refers to X
less pressure ; A low pressure
less oxygen ; A deoxygenated
less glucose ; only accept more glucose if identified as liver
fewer / more, amino acids / fatty acids ;
less water / lower water potential / lower solute potential / higher osmotic pressure / higher
concentration of solutes and / or rbcs ;
A ‘blood is more concentrated’
fewer ions ;
more of named cell product ; e.g. insulin / glucagon / albumen / AW
(more), urea / excretory waste
Describe how carbon dioxide molecules reach red blood cells from respiring cells
diffusion / diffuses ;
down concentration gradient / from high concentration to low concentration / from high to low
partial pressure ;
description of pathway ;
two of the following
cell (surface) membrane of (respiring) cell, tissue fluid, (pore in) capillary wall / endothelium /
endothelial cell, basement membrane / plasma
Explain how the structure of red blood cells is suited to their function of transporting oxygen to body tissues
small size / 6-8 µm (diameter), to squeeze through capillaries (7 µm) ;
2 small size / 6-8 µm (diameter), so, haemoglobin (molecules) near to surface (of plasma
membrane) / reduces distance for diffusion (in / out of rbc) ;
3 no nucleus / lack of organelles, so more room for haemoglobin (so more oxygen
transported) ; R more room for oxygen
4 biconcave shape / diagram drawn, increases surface area for, diffusion / uptake / release
(of oxygen) ;
5 flexible / AW ( membrane), to squeeze through capillaries ;
The circulating red blood cell is metabolically active but only lives for about 120 days. During this time, some important enzymes are gradually broken down and this may contribute to the death of the cell.
Explain why the red blood cell is not able to replace important enzymes that have been broken down.
1 enzymes are proteins, protein synthesis does not occur ;
2 no, nucleus / DNA / genes, so no, transcription / mRNA ; *
3 no mRNA, so no, translation / protein synthesis ;
*A no nucleus, so no protein synthesis for one mark
4 no, RER / ribosomes, site of protein synthesis / AW ;
5 no mitochondria, insufficient ATP (for synthesis) ;
6 no RER for modification (of protein) ; A Golgi apparatus
describe and explain how carbon dioxide (CO2) and hydrogen ions (H+) play a role in the unloading of oxygen from haemoglobin
diffusion of, carbon dioxide / CO2;
2 into red blood cell from correct source ;
3 description of carbonic acid formation followed by H +
production ;
4 ref. carbonic anhydrase ) fast reaction; A ecf from (d)
5 haemoglobin has a higher affinity for hydrogen ions than oxygen ;
A haemoglobin releases oxygen more easily in acidic conditions
accept idea of H + binding to haemoglobin bringing out oxygen release
6 ref. to, allosteric effect / change in tertiary structure / AW, in (oxy)haemoglobin, causes,
release / AW, of oxygen ;
7 formation of haemoglobinic acid ; must refer to, H +
binding / decreased pH
8 ref. higher partial pressures / AW, CO2, linked to (oxy)haemoglobin releasing, more
oxygen / oxygen more readily ; Bohr shift
9 formation of carbamino-haemoglobin ; R carboxyhaemoglobin
10 chloride shift, qualified ;
e.g. as hydrogen carbonate ions move out of cell, chloride ions move in e.g. to maintain,
electroneutrality / a balance of charge / ions ;
Describe and explain the effects of nicotine on the cardiovascular system that can contribute to a person developing coronary heart disease
ref. to coronary arteries ; in correct context makes platelets sticky, so causing blood to clot ;
increases risk of thrombosis in, coronary arteries / arteries to heart (muscle) ;
leading to plaque / atheroma / atherosclerosis / AW ;
increases heart rate ;
increased blood pressure ;
damage to, tunica intima / endothelium /endothelial lining / arterial lining
The production of low-nicotine cigarettes and cigars is considered a strategy that may reduce the harmful effects of smoking.
Explain whether or not you agree with this statement.
agree
less addicted to smoking cigarettes so fewer smoked ;
fewer smoked, so reduced risk of smoking-related diseases ; A named disease
fewer smoked so reduced risk from, (effects of) tar / carbon monoxide ;
disagree as people may smoke more
may smoke more to, increase their nicotine levels / satisfy need for nicotine / AW ;
more smoked, so increased risk of smoking-related diseases ; A named disease
may smoke more so increased risk from, (effects of) tar / carbon monoxide ;
Plants take in mineral ions through their root hair cells. This may happen by a process which moves the ions from a low concentration in the soil to a higher concentration in the root hair cell.
(i) Name and describe this process by which mineral ions are taken in
active, transport / uptake ; [1]
carrier / transport, protein ; A pump protein R channel protein
ref. (protein) changing shape / conformational change ;
ref to specificity ;
ATP / energy, required ;
Water is also absorbed from the soil by the root hair cells.
Outline the mechanism by which this occurs.
osmosis in correct context ; e.g. through, cell surface / partially permeable, membrane or
into, cytoplasm / cell
diffusion, into / through, cell walls ;
from (region of), high(er) / less negative, water potential, to (region of), low(er) / more
negative, water potential or down a water potential gradient ;
transpiration pull ;
Describe the pathway taken by water as it passes from the root hair cells into the cells which are specialised for transport of water and mineral ions.
through cortex / via cortical cells ;
apoplast pathway
(by) via cell walls (of adjacent cells) ; R if named as symplast pathway ;
symplast pathway
via cytoplasm and plasmodesmata ; R if named as apoplast pathway
ref. vacuolar pathway ;
ref. apoplast to symplast / pathway described, at endodermis ;
(via) passage cells ;
ref to, suberised / Casparian, strip ; in correct context
There is a large difference between the percentage saturation of myoglobin and that of adult haemoglobin at low partial pressures of oxygen. Suggest reasons for this.
myoglobin has higher affinity for oxygen / myoglobin binds oxygen while haemoglobin
releases oxygen ; ora
(myoglobin) acts as a store of oxygen ;
myoglobin will only release oxygen, at (very) low oxygen partial pressures / AW when
oxygen demand (in muscles) exceeds supply ; A during exercise
AVP ; e.g. myoglobin has, one / fewer haem groups, so no cooperative binding effects
e.g. allows aerobic respiration to continue (in muscle)
Explain, with reference to Fig. 4.1, the significance of the difference in oxygen binding affinity between fetal and adult haemoglobin.
fetal haemoglobin has higher oxygen affinity (than adult / maternal haemoglobin) /
AW ;
(higher oxygen affinity) over all ppO2 / use of data at more than one ppO 2 (from
Fig. 4.1) ;
oxygen uptake from, adult / maternal, blood / AW ;
or
gas exchange taking place between fetal and, adult / maternal, blood ;
ref. to fetal reliance on mother to supply oxygen / mother only source of oxygen for
fetus ; [2]
In a rare condition known as Hereditary Persistence of Fetal Haemoglobin (HPFH), fetal haemoglobin continues to be produced well into adulthood in addition to adult haemoglobin. This condition, however, usually lacks any symptoms.
Suggest why HPFH usually lacks symptoms
at lower ppO2 both, unload / AW, oxygen ;
sufficient / more, adult haemoglobin present or adult haemoglobin provides sufficient
oxygen / AW ;
ref. to compensating by producing additional red blood cells ;
AVP ; e.g. ref. to similarity of position of both curves
For Examiner’s Use
(c) Describe how the assimilate you have named in (b)(i) is transported from the source to the sink.
1 H +
/ protons, (move) out of companion cells by, active transport / AW ;
R diffuse by active transport
2 H +
/ protons, diffuse (back) in with / cotransport sucrose, into companion cells ;
A description of (facilitated) diffusion
R active transport
ref. to companion cell required only once for mps 1 and 2
3 via, cotransporter / cotransporter described ;
4 sucrose, diffuses / AW, into (phloem) sieve, tube / element, via plasmodesmata ;
5 (entry of sucrose into sieve tube so) water potential lowers ;
6 water enters by osmosis ;
7 (hydrostatic) pressure builds up ; A pressure difference created
8 unloading at, sink / named sink, gives a difference in pressure (between source and
sink) ; AW
9 (so) mass flow ; term to be used in context
Aphids are insects with mouthparts adapted to penetrating the cells of plants which transport assimilates.
Suggest why aphids feed specifically from these cells.
obtain, sucrose / amino acids / other named assimilate ; R nutrients unqualified
pressure forces, sap / AW, into aphid ; [max 1]
The blood vessel that transports deoxygenated blood from the heart.
pulmonary artery
The cell that ingests and digests cell debris and bacteria in the lungs
phagocyte
The cell that secretes antibodies
B-lymphocyte / (effector) B (cell) / plasma (cell)
The epithelial cell that secretes mucus in the trachea
goblet (cell
The tissue that prevents the collapse of the trachea during inhalation.
cartilage
State one role of vacuoles in plant cells.
store of / holds, cell sap ; R if contains organelles
store of / holds, water / ions / named ion(s) / minerals / salts / pigments / (named) sugars ;
R substances / molecules
R storage unqualified
pushes chloroplast to edge of cell ;
gives, turgidity / turgor pressure / hydrostatic pressure / support / AW ;
A makes, firm / rigid
A controls / maintains, turgidity
Explain how the composition of the cell surface membrane determines the permeability
of the cell surface membrane
1 F partially permeable A selectively permeable
and G (fully / freely / AW), permeable / porous ;
F is partially permeable cell surface membrane
2 phospholipid (bilayer);
3 permeable to, lipid-soluble molecules / oxygen ;
A other terms for lipid-soluble
treat reference to water as neutral
4 impermeable to, water-soluble / AW, molecules / ions / AW ;
A other terms for water-soluble
treat reference to water as neutral
5 aquaporins / proteins, provide (increased) permeability to water ;
6 transport proteins provide permeability to, ions / polar molecules ;
A channel / pore / carrier, proteins
Explain how the composition of the permeable cell wall determines the permeability
of the cell surface membrane
G is permeable cell wall 7 cellulose ; 8 fibres ; 9 ref. to, spaces / gaps / holes / pores, (between, fibres / other cell wall components) ;
Describe the roles of plasmodesmata in transport in plants.
allows transport of, water / sucrose / amino acids / organic substances / ions /minerals /
salts / lipids / hormones / ATP, (from cell to cell / between cells) ;
R if linked to an incorrect transport mechanism e.g. sucrose moves by osmosis
2 without crossing, membranes / walls ; A without going through protein channels
3 this is movement through the symplast ;
4 any e.g. ; companion cell to (phloem) sieve tube (element / cell)
between mesophyll cells
mesophyll cell to companion cell
cortical cell to cortical cell / across cells of the cortex
cortical cell to endodermal cell
endodermal cell to, pericycle cell / xylem / phloem
ignore between sieve tube elements
5 allows, communication / signalling, between cells ;
Explain the advantage of the position of the dissociation curve for people with sickle cell
anaemia.
at partial pressures in the tissues ; where oxygen is unloaded from Hb
2 haemoglobin is less saturated (than L) ;
3 because, haemoglobin / Hb, dissociates more readily ;
A idea of unloading oxygen more readily even if Hb not mentioned
4 to compensate for, fewer / less effective, red blood cells / Hb ;
Describe and explain how humans become adapted to the low partial pressure of
oxygen at high altitude
haemoglobin less well saturated (in lungs at high altitude) ;
2 data quote from Fig. 3.1 ; A 80–90% saturated at ‘about 7.5 kPa’
3 produce more red blood cells / increase in number of RBCs ;
4 more haemoglobin ;
5 idea of compensates for, smaller volume of oxygen absorbed / lower saturation (of
haemoglobin) ;
also accept the following adaptations
6 increase in haematocrit / AW / decrease in plasma volume ;
A increase in RBCs per unit volume
R decrease in blood volume
7 increase in, breathing rate / tidal volume / heart rate / stroke volume ;
8 increase in, capillary density / number of mitochondria / myoglobin / respiratory
enzymes, in muscle ;
9 ref. to (increased) secretion of, erythropoietin / EPO ;
10 increase in (2,3), BPG / DPG, in red blood cells ; A rightward shift in curve
Explain why vaccination cannot be used to prevent sickle cell anaemia
not caused by (named type of) pathogen / non-infectious / non-transmissible / noncommunicable
/ AW ;
2 genetic / inherited / AW, disease ; A caused by a mutation / AW
A ‘passed down from parent(s)’
R idea of congenital diseases
R ‘you get it from your mother’
3 ref. to, no immune response / no antigen(s) ;
4 affects all red blood cells so vaccine would lead to their destruction ;
Explain how capillaries are adapted for their function as exchange vessels.
1 (capillary) wall is, thin/ single layer of cells / one cell thick ;
A endothelium/ epithelium for wall
2 short diffusion, pathway / distance/AW ;
R ‘easy’ diffusion
3 (many have) endothelial pores / fenestrations / gaps / spaces / openings ;
4 to allow named, substance/ cell, to leave the blood ;
A idea of separation/ selection, of named substance(s) by size
5 small diameter/ small lumen/ diameter of red blood cells ;
6 slows down flow of red blood cells /(capillary / blood) close to cells ;
7 (capillaries have) large, surface area/ surface area to volume ratio ;
8 idea that allows more exchange ;
Explain the differences between the composition of blood, tissue fluid and lymph for white blood cells
te blood cells
1 (named) white blood cells can, leave capillaries / enter tissue fluid ;
A diapedesis /(suggestion that some) too large to leave the, blood/ capillaries
2 high number in, lymph nodes / thymus / bone marrow/ spleen ;
A stored/ produced
Explain the differences between the composition of blood, tissue fluid and lymph for glucose
small (molecule) ;
4 filtered/ diffuses /leaves / leaks, from blood/ from capillaries / into tissue fluid ;
5 taken up/ used, by cells in respiration ;
Explain the differences between the composition of blood, tissue fluid and lymph for protein
too large to, leave capillaries / enter lymph/ enter tissue fluid ;
7 (in lymph / tissue fluid) antibodies / proteins, from/ secreted by, lymphocytes / other
cells ;
Outline how red blood cells are involved in the transport of carbon dioxide
carbon dioxide, reacts / combines, with (terminal amine/N terminal, of) haemoglobin ; R carried by /reacts with, haem 2 to form carbaminohaemoglobin ; 3 carbonic anhydrase catalyses, formation of carbonic acid (H2CO3)/reverse reaction described (in the lungs) ; 4 (carbonic acid dissociates to) HCO3 – /CHO3 – / hydrogen carbonate (and H+ ) ; 5 hydrogen carbonate/HCO3 – , diffuses /moves /AW, out (into plasma) ;
Transpiration is often described as an ‘inevitable consequence of gas exchange in
plants’.
Explain what is meant by this statement.
stomata open(ings) to allow carbon dioxide in ;
carbon dioxide required for photosynthesis ;
water vapour diffuses out through stomata ;
Describe three ways, other than small size, in which leaves are adapted to reduce the
rate of transpiration.
stomata close (for longer), during the day /when hot/when dry ;
2 stomata in pits / sunken stomata ;
3 stomata only on lower surface of the leaf ;
4 hairs / trichomes ;
5 low number of/ few(er)/ less, stomata (per unit area) ;
ignore ‘less open stomata’
6 thick(er) cuticle;
7 reflective cuticle (on upper epidermis) ;
8 thick(er) epidermis / more than one layer of epidermal cells ;
9 curled/rolled/AW, leaves ;
) Aquaporins are membrane channel proteins in plant and animal cells. They permit the
movement of water across membranes. Explain why they are necessary
water molecules are polar
idea that few polar molecules pass through the phospholipid (bilayer) ;
ora for non-polar molecules
A none pass /repelled
3 core of membrane/ phospholipid tails, are hydrophobic ;
A hydrophobic core
4 channels (through aquaporins), are hydrophilic ;
A core of channel proteins /described as R-groups of amino acids
5 (aquaporins) increase permeability of membrane to water ;
6 example ;
e.g. root hairs / small intestine epithelium/ nephron
7 role of water in a cell ;
e.g. solvent/reactant/reaction medium/ turgidity or support in plant cell
State three structural features that are present in a mesophyll cell in a leaf that are not
present in a prokaryotic cell
chloroplast ; A grana/ thylakoid(s) A plastid
(permanent) vacuole/tonoplast ; R vesicles unqualified A lysosome
mitochondrion/mitochondria ; A cristae
Golgi (body / apparatus / complex)/ dictyosome ; A Golgi vesicle(s)
rough endoplasmic reticulum/rough (ER)/RER ;
smooth endoplasmic reticulum/ smooth ER/SER ; A endoplasmic reticulum, if RER and SER
not given
nucleolus ;
linear/AW, chromosomes ; A DNA + histones
cellulose cell wall ;
starch grain/ amyloplast ;
plasmodesma(ta) ;
larger/ 80S/ 22nm, ribosomes ;
