all8. Flashcards
Explain why organisms larger than organism C (single celled) need to have transport systems.
surface area relative to volume too small/AW;
diffusion too slow/AW; idea of speed needed
distance too great/some cells deep in body/not all cells in contact with
environment/AW; R large if unqualified
insufficient/AW, oxygen/(named) nutrient, supplied/(named) waste removed;
idea of linking (named) areas; look for ‘from…’ ‘to…’ with an
implication of organs, not just ‘all over body’
(may be,) more (metabolically) active/AW/, homoiothermic;
features of the alveolus/alveolar air, sac/space which make it suitable for gas exchange.
large surface area to volume (ratio)/AW; thin/one cell thick, wall/short diffusion distance/AW; A appropriate figures for width squamous epithelium; permeable; blood supply, qualified; elastic tissue/recoil (after expansion); surfactant;
a closed system
the blood flows in vessels
a double circulation
blood passes twice through the heart for one complete circuit of the body
Purkyne tissue
transmits waves of excitation to the base of the heart
conducts waves of excitation over the walls of the ventricles
fibrous tissue between the atria and the ventricles
is unable to conduct waves of excitation
atrioventricular node (AVN)
delays transmission of the waves of excitation by about 0.1 s
sinoatrial node (SAN)
initiates the cardiac cycle
coronary artery
carries oxygen to the heart muscle
neutrophil/phagocyte function
phagocytosis/engulfing
Describe how red blood cells are adapted for their function.
1 haemoglobin/haem, carries oxygen/AW;
2 detail of no. of oxygen molecules carried;
3 small size/large SA:V ratio, so haemoglobin never far from cell
surface/AW;
4 flexible/elastic/stretchy/changes shape/AW;
5 small size/‘stretchiness’/AW, allows red cells to, fit/squeeze, into
capillaries;
6 biconcave/AW [A ‘dimpled’], gives, increased/AW, surface area
relative to volume (for diffusion);
7 no nucleus to maximise room for, haemoglobin/oxygen/AW;
8 contain carbonic anhydrase;
9 describe, the reaction catalysed by carbonic anhydrase/role in
maintenance of diffusion gradient/AW;
10 transport of carbon dioxide as carbamino-haemoglobin/CO2
combines with Hb;
11 ref buffering effect;
12 AVP; e.g. further detail of oxygen carriage
variable oxidation state of Fe
idea that small size allows them to be close to tissue or cells
lack of, other/named, named organelles, also increases
room for Hb/O2
With reference to the definition of transpiration and the apparatus (photometer) in the diagram above, explain why the results gained by using the apparatus are not measures of the actual transpiration rate.
transpiration is the loss of water, vapour/by evaporation;
(apparatus) measures water uptake;
to replace loss;
assumes all uptake is lost/AW; ora some may be used
explanation of how some uptake may be used e.g. used to regain
turgor/used in photosynthesis;
uptake by detached shoot may not be same as whole plant
potometer set up- controls
cut shoot under water/insert into apparatus under water/AW;
cut shoot at a slant;
no, airlocks/bubbles/AW in, plant/apparatus, or airtight/watertight, joints;
dry off leaves/AW; use a healthy/undamaged/AW, shoot; A fresh
allow time to acclimatise/AW;
keep (named) condition(s) constant; R ‘control’ conditions if unqualified
measure per unit time;
Describe the precautions you would take when setting up and using a photometer in order to get valid readings from which the transpiration rate can be estimated.
cut shoot under water/insert into apparatus under water/AW;
cut shoot at a slant;
no, airlocks/bubbles/AW in, plant/apparatus, or airtight/watertight, joints;
dry off leaves/AW; use a healthy/undamaged/AW, shoot; A fresh
allow time to acclimatise/AW;
keep (named) condition(s) constant; R ‘control’ conditions if unqualified
measure per unit time;
why it is important that red blood cells are stored in a solution with a suitable water potential
prevents osmosis;
no net movement of water/AW;
prevents bursting/lysis/crenation/AW;
why xylem is described as a tissue
made up of, more than one / two / a few, types of cell
working together / AW;
with a, specific / particular / same, function / role / purpose / job;
Prokaryotic cell structure
no, nucleus / nucleolus / nuclear membrane / nuclear envelope A free DNA circular DNA A loop no, histones / (true) chromosome A naked DNA no membrane-bound organelles cell wall peptidoglycan / murein, cell wall ribosomes, 18 nm / 70S / smaller plasmids AVP e.g. no cytoskeleton flagellum not 9+2 pili fimbrae capsule mesosome
Eukaryotic cell structure
nucleus / nucleolus / nuclear membrane / nuclear envelope A DNA enclosed linear DNA histones / chromosome A DNA + protein membrane-bound organelles/ named e.g. (Allow up to 2 marks) may have cell wall cellulose cell wall (if present) ribosomes, 22 nm / 80S / larger no plasmids (except inside organelles) AVP e.g. cytoskeleton flagellum 9+2 no pili no fimbrae no capsule no mesosome
the stage of the mitotic cell cycle in which each of the following takes place
chromosomes become visible as two chromatids
prophase;
the stage of the mitotic cell cycle in which each of the following takes place
DNA replicates
interphase / S phase;
the stage of the mitotic cell cycle in which each of the following takes place
nuclear envelope reforms
telophase
During mitosis, chromosomes line up at the equator of the cell.
Describe what happens to chromosomes after this, until the nuclear envelope reforms.
1 attach to spindle;
2 by centromere;
3 centromere, divides / splits; R breaks
4 spindle fibres shorten / AW;
5 chromosomes / chromatids, pulled to, poles / centrioles /
different ends of cell / different ends of spindle;
nucleus / 1 of each pair
6 centromere leading;
7 detachment from spindle fibres;
8 (start to) unravel / uncoil / decondense / lengthen / AW
Goblet cell function
in bronchus wall
produce / secrete / release, mucus;
Cartilage function (in bronchus wall)
prevent collapse of / hold open / support, airways;
ways in which the structure of the wall of the bronchus would be different in a long-term smoker
cilia, destroyed / damaged
(epithelium replaced by) scar tissue / scarring;
(smooth) muscle becomes thicker;
mucous glands enlarge / larger goblet cells / more goblet cells;
inflammation of connective tissue;
Gaseous exchange occurs across the walls of the alveoli.
Explain why the walls of the alveoli contain elastic fibres
stretch, as air is inhaled / allow alveoli to expand during inhalation;
to increase lung volume / surface area;
prevents alveoli bursting;
(elastic fibres) recoil, as exhale;
more, complete / rapid, expulsion (from the alveoli);
One feature of the disease emphysema is that the alveoli lose their elasticity.
Explain the effects of this loss of elasticity on the gaseous exchange system of a person with emphysema.
tidal volume is reduced / less air inhaled and exhaled / residual
volume is larger / air trapped in alveoli / vital capacity smaller;
more difficult to exhale;
(as) alveoli cannot, stretch / recoil;
rapid / shallow, breathing / breathlessness / wheezing;
alveoli may burst;
leaves gaps in tissue / larger air spaces / AW;
less surface area (for gaseous exchange);
blood / haemoglobin, less well oxygenated / less carbon dioxide
removed;
Explain how the lumen of the artery has become narrowed at point Y.
high concentration of, cholesterol / LDL, in blood;
endothelium / lining damaged;
deposition (fat / cholesterol) in wall of artery; R “on artery”
ref to plaque / atherosclerosis / atheroma
how doctors might treat a patient with narrowing of the arteries that supply the heart muscle
ref to suitable drug; e.g. anticlotting, blood pressure reducing, diuretic
bypass operation;
stents fitted;
angioplasty / balloon on catheter;
pieces of advice that a doctor might give to such a patient to try to reduce the likelihood of further narrowing of the arteries
avoid, saturated / animal, fats; A cholesterol
eat, unsaturated fats / polyunsaturated fats / plant oils / fish oils;
qualified ref to, more / regular, exercise;
avoid smoking;
avoid stress;
eat more, fruit / vegetables / antioxidants; A moderate intake of red wine
reduce weight;
reduce alcohol intake;
eat more soluble fibre;
ref to vitamin D production / exposure to sunlight;
The diagram shows that the pressure rises and falls in the arteries.
Explain what causes this rise and fall in pressure.
the heart / ventricle / cardiac muscle (involved);
peaks coincides, with, systole / contraction; R pump
troughs coincide, with, diastole / relaxation / AW;
stretch-recoil effect / AW;
The diagram shows that:
• the rise and fall in pressure seen in the arteries is not evident by the time the blood enters the capillaries
• the pressure is much lower by the time the blood enters the capillaries.
Explain what causes the changes described above.
distance (from heart) qualified, e.g. further / around the body / AW;
friction / resistance to flow / AW;
less / no, stretch-recoil effect / AW;
increasing volume of, arterioles / capillaries
why it is important that the pressure is lower by the time blood reaches the capillaries
stop damage (to capillaries );
A stop bursting R ‘can’t cope’ A ‘can’t withstand’
lack of (much) elasticity / thin / delicate / fine / one cell thick /
no collagen / no muscle; ora for artery wall
slows flow rate;
allows time (for);
exchange / AW; A one named substance moved, but R “food”
oedema risk reduced / high pressure might force out more tissue fluid;
The pressure in veins is very low. Explain how the blood in veins is returned to the heart
valves prevent backflow / AW;
action of (skeletal) muscle; R if muscle in vein wall implied
residual pressure / AW;
large lumen provides little resistance / AW;
negative pressure in, chest / thorax / heart; A respiratory pump
gravity effect (from areas above heart);
features of root hair cells which adapt them for water uptake
large surface area (to volume) / many; low water potential; thin wall / short diffusion path; uncutinised / permeable / unlignified / AW; rapid, growth / replacement;
Plants absorb water from the soil via their roots.
Describe the pathways and mechanisms by which water passes from the soil to the xylem vessels in the root.
1 osmosis in correct context;
look for across membrane, or, into / out of, cell / root
2 moves down a water potential gradient / from high to low
water potential;
R along / across R concentration / diffusion gradients
3 most negative / lowest, in the xylem;
4 (uptake of) ions / minerals / solutes, into xylem / root hair;
in context of WP gradient
5 tension in xylem / transpiration pull / cohesion-tension;
relate to pathway in root
6 (moves) via the cell walls;
7 (moves) via, cytoplasm / vacuoles;
8 passage via the plasmodesmata; look for linking cytoplasm /
through wall
9 Casparian strip / suberin / waxy / fatty / AW, blocks,
cell wall route / apoplast; A waterproof
10 water, crosses membrane / enters, cytoplasm / vacuole / symplast;
11 AVP; e.g. pits in xylem / passage cells /aquaporins /
protein channels / capillarity in cell wall (spaces)
After water has entered the xylem vessels in the root, it passes through them to the rest of the plant.
Describe how features of xylem vessels adapt them for water transport.
lignin / AW;
(allows) adhesion / waterproof / stops collapse (under tension);
A two functions
rings / spirals / thickening / AW; A thick wall / rigid sides
prevents collapse (under tension); R strong / support / stops bursting
no cytoplasm / lack of contents / hollow / (empty) lumen / AW;
R “dead” unqualified
less resistance to flow / ease of flow / AW / more space (linked to
lack of contents);
lack of end walls / continuous tube; A long tube idea
less resistance to flow / ease of flow; A continuous columns idea
pits / pores, inside walls; A holes R gaps
lateral movement / get round air bubbles / supplies(water) to cells or
tissues / water in or out; R “just let things in and out” unqualified
develop as a continuous water-filled column / AW;
allows tension to pull water up / AW;
narrow lumen / AW;
idea of more capillary rise;
The difference in thickness of the walls of the chambers, atrium, left ventricle, right ventricle , is related to the functions of the different chambers
atrium / X, (only) has to pump, to ventricles / short distance;
ora for ventricles A ref to gravity effect / negative ventricle pressure
left ventricle / Y, has to pump to, body / systemic circulation, and,
right ventricle / Z, has to pump, to, lungs / pulmonary system;
comparison of Y and Z
left ventricle / Y, pumps, further / great(er) pressure;
ora right ventricle / Z A to all / whole body idea as distance
left ventricle / Y, pumps against great(er) resistance;
ora right ventricle / Z
Why without the Purkyne tissue, blood would not be pumped out of the heart efficiently.
(Purkyne fibres) conduct wave of excitation / AW; R impulse, signal, pulse to the, base / apex, of heart; so contraction occurs upwards / AW; both ventricles contract together;
why it is essential that the fetus has a different type of haemoglobin from the adult
1 fetus gains oxygen, from mother / across placenta;
2 partial pressure of oxygen in placenta low;
3 2-5 kPa; A any figure within range
4 maternal (oxy)haemoglobin releases oxygen;
R if stealing / taking oxygen from mother is given
5 fetal haemoglobin has a high(er) affinity for oxygen;
A binds more strongly
6 maintains a diffusion gradient / AW; max
why the change from fetal to adult haemoglobin seen in the diagram above is essential after birth
7 oxygen would not be released readily enough / AW;
8 (because) affinity of fetal haemoglobin would be, too /
very / so, high;
only accept higher/high if linked to oxygen release
9 ref to idea that adult (females) will need difference with
their fetuses in due course;
Respiring tissues in the body produce carbon dioxide which diffuses…
into the blood.
Most of it then enters red blood cells where an enzyme named … catalyses a reaction
carbonic anhydrase
carbonic anhydrase catalyses a reaction to produce……
carbonic acid / H2CO3;
carbonic acid dissociates rapidly into hydrogen ions and……ions
hydrogencarbonate / HCO3
The hydrogen ions combine very readily with haemoglobin to form a compound known
a……….
haemoglobinic acid
why a large number of stomata are measured in order to calculate a mean
to take account of variation / AW;
reliable or representative / smaller SD or % uncertainty;
ignore “accurate”, “precise”
so result not skewed by, anomalies / extreme or unusual results;
to ensure statistical significance;
ways in which photographing the leaf surfaces makes measuring the stomata easier
permanent record;
avoid, heating effect / light, of microscope lamp;
stomata size may change (under microscope);
photograph can be enlarged;
measuring can be done at leisure;
Mitochondria function
aerobic respiration; ATP production; A provides ATP energy release; A provides energy R produce / create / make / etc AVP; e.g. Krebs cycle / regenerate NAD oxidative phosphorylation protein synthesis lipid synthesis oxidation of fats ornithine / urea, cycle
why ciliated cells contain relatively large numbers of mitochondria
(energy / ATP needed) for, movement / wafting (of cilia);
