all9.

Question 1

Why using a light microscope to produce an image to the magnification of x20,000 would be of little use

Answer 1

low resolution; ora
(close) points not easily distinguished;
wavelength (of visible light) is too long;
max resolution of light microscope =, 200 nm / 0.2 µm; A anything close
no more detail visible than seen at, ×1500 / ×1000;

Question 2

Describe what happens within the vacuole after it fuses with the lysosome

Answer 2

enzymes / named enzymes / lysins;
acid / low pH;
digestion; A breaking down
breaking, peptide / glycosidic / ester, bond; R if in wrong context
hydrolysis;
soluble / named, products;

Question 3

Ovary cells contain large amounts of endoplasmic reticulum (ER).
Suggest the importance of this in using these cells for the production of Factor VIII.

Answer 3

(rough) ER has ribosomes; R produces
for, protein synthesis / translation;
ER transports protein through cell;
forms vesicles;
for transport to / forming, Golgi;
(in Golgi) modification of protein / glycosylation;

Question 4

the stage in mitosis that immediately follows prophase

Answer 4

metaphase

Question 5

the behaviour of the chromosomes in metaphase

Answer 5

individual) chromosomes align at,
metaphase plate / equator / centre (of cell);
join to, spindle / microtubules;
by centromeres;

Question 6

Features of the lung that permit efficient gas exchange

Answer 6

many, air spaces / alveoli;
large surface area; R ref to surface area to volume ratio
thin wall of, alveolus / capillary; A one cell thick R ‘thin wall’ on its own
good blood supply / large capillary network;
air passage / bronchiole;
capillary close proximity to alveolus;

Question 7

At a certain point, the student was asked to breathe in as deeply as possible and then breathe out as much as possible. What is this measuring

Answer 7

vital capacity

Question 8

Explain how differences in SA:V ratio have influenced the need for transport systems in mammals

Answer 8

diffusion not adequate / AW / ora;
as not enough area (relative to volume); ora
distance too great / cells deep in body / AW; ora, R large unqualified
mass flow system needed;
transport / blood (vascular), systems, link, the parts of the body /
named parts;
e.g. of substance needing to be transported; R ‘gases’ / ‘waste’ / ‘food’
ref to activity / high metabolic rate, of mammals;

Question 9

parts of the mammalian body where the surface area is relatively large to allow effective functioning

Answer 9

alveoli
lung
villi
gut
small intestine A intestine
capillary bed / capillaries / AW
skin qualified e.g. elephant’s ears
cerebral cortex / brain
kidney (tubule)
liver

Question 10

Heart wall muscle is a special type of muscle called….

Answer 10

cardiac muscle

Question 11

cardiac muscle can contract or relax without nervous stimulation and is thus described as….

Answer 11

myogenic

Question 12

To ensure that the cardiac cycle stays in sequence

there is…

Answer 12

an in-built control mechanism

Question 13

The wall of the right atrium contains a special

region of muscle called the…

Answer 13

sinoatrial node

Question 14

The sinoatrial node sets up a wave of

electrical activity causing…

Answer 14

the atrial walls to contract almost simultaneously

Question 15

There is a

band of fibres between the atria and ventricles which stop / prevent

Answer 15

the

wave of activity passing to the ventricle walls.

Question 16

Transpiration definition

Answer 16

evaporation of water / water vapour lost (from plants);
diffusion,
into atmosphere / out of leaf / down a water potential gradient /
via stomata;

Question 17

Explain why transpiration in plants cannot be avoided.

Answer 17

linked to gas exchange / AW; A refs to both oxygen and carbon
dioxide unqualified carbon dioxide for photosynthesis;
open stomata;
large area; can apply to leaf area or pore area
moist mesophyll to (relatively) dry air / water potential gradient / AW;
AVP; e.g. ref to some cuticular transpiration inevitable / AW
link open stomata to daytime when it is hottest / AW

Question 18

Explain how a covering of leaf epidermal hairs helps xerophytes survive in their habitat.

Answer 18

hairs trap water vapour; R water unqualified / water particles A molecules
reduces water potential gradient / stops wind removing vapour /
more humid air around leaf; ecf for water
so less transpiration / AW;
AVP; e.g. ref reflective nature of hairs in context
ref to need of xerophytes to conserve water in dry habitat

Question 19

Explain how water travels up the stem and into the leaf of a dicotyledonous plant.

Answer 19

1 in the xylem vessels; A tracheids
2 down a, water potential / Ψ, gradient;
R ‘along’ A refs to high to low water potential
3 most negative, at the leaf / in the atmosphere;
ora must refer to water potential
4 transpiration sets up a gradient / AW; any valid gradient
5 (places) water (in xylem) under, tension / suction / negative pressure /
pull / hydrostatic pressure gradient / AW;

6	cohesion;
7	description of cohesion;
8	ref to hydrogen bonding;
9	(continuous) water columns / AW;
10	mass flow;
11	root pressure, in context / described;
12	adhesion described / capillarity;

Question 20

why squamous epithelium is described as a tissue

Answer 20

(made up of) one type of / (squamous) epithelium, cell(s);
A same R similar alone
(group of) cells performing the same function(s);

Question 21

features of a gas exchange surface, such as the lining of the alveolus

Answer 21

large surface area;
permeable;
thin / short, diffusion path;
moist;
good blood supply / close to blood;
well ventilated / in contact with respiratory medium;

Question 22

Describe how other molecules or ions cross a plasma (cell surface) membrane by active transport and facilitated diffusion.

Answer 22

active transport
1 against concentration gradient / described; A up
2 uses, energy / ATP;
facilitated diffusion
3 down concentration gradient / described; A with R along / across
4 no, energy / ATP, required; A passive
protein carrier (in either or undefined)
5 attaches on one side of the membrane;
6 protein, moves / turns / changes shape;
7 releases on other side of the membrane;

channel protein (facilitated diffusion only) 8	forms, pore / passage, through centre of the protein; 9	hydrophilic conditions / water lined; 10	phospholipid (bilayer) prevents, diffusion / passage / entry, of (some), molecules / ions;	R substances 11	polar / water soluble / not lipid soluble / too big / suitable named e.g.; 12	appropriate use of protein in both; 13	ref to specificity of protein to substance transported; 14	AVP; (for extra detail of transport mechanism)

Question 23

The term which refers to any organism that causes infectious disease.

Answer 23

pathogen;

Question 24

Diseases which cause a progressive deterioration of part of the body.

Answer 24

degenerative;

Question 25

The type of exercise that uses the heart and lungs to provide oxygen for respiration in muscles.

Answer 25

aerobic;

Question 26

The volume of air breathed in or out during a single breath.

Answer 26

tidal;

Question 27

A term used to describe a disease that spreads across continents.

Answer 27

pandemic;

Question 28

the carbohydrate that is transported in phloem

Answer 28

sucrose

Question 29

Outline how = companion (cell) and sieve (tube) element / sieve tube cell; are involved in the transport of carbohydrate in phloem.

Answer 29

1 sieve elements / Q, end to end or sieve plates perforated / sieve pores, for ease of flow / AW; 2 companion cells / P, metabolically active / have many mitochondria / produce ATP / release energy / AW; R make energy 3 (active) loading into, companion cell / P; A into, sieve elements / Q 4 ref to proton pump; 5 ref to co-transporter; 6 role of plasmodesmata (between P and Q); R pores 7 sieve element / Q, has few organelles / AW, for, ease of flow / more sucrose / AW; 8 ref to, unloading mechanism / (hydrostatic) pressure gradient; 9 ref to one role for sieve plate e.g. electro-osmosis or stops ‘bulging’;

Question 30

Carbohydrate moves from regions of plants called sources to regions called sinks. Explain how, at different times, the same plant root may be a source or a sink.

Answer 30

source when root converts, starch / insoluble carbohydrate, into sugars / AW; sink when root either stores starch / (named) carbohydrate / assimilate or uses carbohydrate for, respiration / growth / AW; high hydrostatic pressure makes it a source and low hydrostatic pressure a sink; when loading it is a source and when unloading a sink;

Question 31

Describe how the structure of an artery is related to its function.

Answer 31

1 ref to tunica, intima / interna, tunica media and tunica, externa / adventitia; 2 thick wall, stops bursting / withstands pressure idea; 3 (relatively) narrow lumen to maintain pressure; 4 elastic tissue / AW, allowing stretching / AW; 5 elastic arteries near heart; 6 elastic recoil; 7 to even out surges of pressure / to maintain flow / AW; A push idea 8 collagen provides (main) strength / AW; 9 (smooth) endothelium (of tunica intima) to reduce friction / AW; A epithelium or lumen lining / AW R epidermis 10 tunica media / AW, has (smooth) muscle and elastic tissue; collagen is neutral 11 to prevent bursting / withstands pressure / AW; look for link to tunica media 12 (smooth) muscle maintaining pressure; A ref vasoconstriction / ‘blood shunts’ R pumping action 13 AVP; e.g. idea that circular cross section allows max blood volume for minimum wall contact / AW award QWC mark if three of the following are used tunica (qualified once) lumen elastic / elastin collagen recoil smooth muscle endothelium vasoconstriction

Question 32

The blood also contains hydrogen carbonate ions (HCO3–). Describe how these ions are formed in the blood.

Answer 32

``` carbon dioxide (diffuses) into red blood cells; R blood only carbonic anhydrase; carbon dioxide reacts with water; to form, carbonic acid / H2CO3 / HCO3–; R if linked with incorrect reaction carbonic acid, dissociates / AW, to give HCO3–; accept from equations CO2 + H2O → H2CO3 H2CO3 → H+ + HCO3– ```

Question 33

Suggest the consequences of a blockage at the coronary artery

Answer 33

oxygen / glucose, will not reach, (heart / cardiac) muscle; A less reduced / no, respiration; (possible) coronary / heart attack / myocardial infarction / (possible) death;

Question 34

Definition: closed system

Answer 34

blood enclosed in vessels

Question 35

why the mammalian system is called a complete double circulation whilst that of the frog is called a partial double circulation.

Answer 35

ventricles not separated / one ventricle / partial or no septum / three chambers / left and right sides not separated; ora for mammal single vessel from heart; ora for mammal A aorta oxygenated and deoxygenated blood not (fully) separated; ora for mammal blood passes twice through heart for complete circulation / systemic and pulmonary systems / to lungs and body;

Question 36

why the system shown for the frog may be less effective at supplying the body tissues with oxygen

Answer 36

blood will not be fully oxygenated / Hb less fully saturated / deoxygenated and oxygenated blood mixed / AW; still carrying carbon dioxide; lower pressure or less, force / push / AW;

Question 37

one way in which the dissociation curve for lugworm haemoglobin differs from that for human haemoglobin

Answer 37

lugworm haemoglobin has a high affinity for oxygen ; low oxygen in, lugworm habitat / water / ora ; lugworm haemoglobin, stores oxygen / only releases oxygen when pp O2 very low ; two haemoglobins have different, structures / amino acid sequences ;

Question 38

Describe the similarities and differences between the adaptations for gas exchange and transport of oxygen in mammals and lugworms.

Answer 38

D1 ref to lugworm gills and mammal, alveoli / lungs ; D2 ref to internal and external, exchange surfaces ; D3 less oxygen in, water / sand ; A ora D4 lugworm haemoglobin adapted to, water / sand/ low O2 environment ; A ora D5 lugworm has no red blood cells / ora ; D6 detail of mammalian red blood cells ; D7 lung ventilation tidal / lugworm, throughflow / unidirectional / AW ; D8 AVP ; e.g. ref. water loss from lungs similarities (max 5) S1 both (gas exchange surfaces have) large surface area ; S2 both, thin / have short diffusion distance ; S3 both well-vascularised ; S4 both moist ; S5 ref to diffusion of, oxygen / carbon dioxide / gases ; S6 (blood carries) oxygen to tissues ; S7 haemoglobin transports oxygen ; S8 both move medium over gas exchange surface ;

Question 39

one way in which root hairs are adapted to increase uptake

Answer 39

long; thin cell wall; lack of, waterproof layer / cuticle; large surface area; NOT if cilia / villi / microvilli / tails / etc present in large numbers; (membrane) proteins / carriers / channels / aquaporins; many mitochondria;

Question 40

method used by root hairs to take up nitrate ions

Answer 40

active transport / diffusion / facilitated diffusion / described; A pinocytosis

Question 41

Outline the process by which water enters the cells of the root from the soil

Answer 41

lower water potential inside / ora; movement, down water potential gradient / from high Ψ to low Ψ; through, channel proteins / partially permeable membrane / aquaporins / AW; walls freely permeable; osmosis;

Question 42

Outline what happens to chromosomes during the mitotic cell cycle.

Answer 42

prophase 1 C; 2 chromosomes / chromatids, condense / coil / shorten and thicken; 3 become visible; 4 consist of two chromatids; 5 joined by a centromere; A kinetochore NOT centrosome metaphase 6 A; 7 chromosomes align at, equator / metaphase plate; 8 attached to spindle by centromeres; ``` anaphase 9 B; 10 centromere splits; 11 chromatids separate; 12 move to opposite poles; 13 by, contraction / shortening, of spindle; telophase 14 E; 15 chromosomes uncoil; ``` interphase 16 D; A for a description of early prophase 17 DNA replication; 18 transcription / formation of mRNA; 19 AVP; these must relate to behaviour of chromosomes 20 AVP; e.g. spindle made of microtubules chromatin becomes chromosomes (in prophase) ora in interphase centromere leads chromatid to pole gene switching during interphase 9 max QWC – clear well organised using specialist terms; 1 award the QWC mark if three of the following are used in correct context, but Q = 0 if names or names of stages of mitosis are used inappropriately chromatin equator / metaphase plate chromatid DNA replication centromere transcription spindle

Question 43

Describe how the tissues in the gaseous exchange system contribute to the functioning of the lungs.

Answer 43

``` cartilage 1 in, trachea / bronchi; 2 holds airway open / prevents collapse; 3 prevents bursting (of trachea / bronchi as air pressure changes); 4 low resistance to air movement; ``` ciliated epithelium / cilia 5 move mucus; 6 ref to how movement brought about; e.g. metachronal rhythm / wave / sweep / waft goblet cells 7 secrete mucus; 8 trap, bacteria / dust / pollen / particles; 9 remove particles from lungs; blood vessels 10 supply, oxygen / nutrients (to tissues of lung); 11 surround alveoli / good blood supply to alveoli; 12 deliver carbon dioxide / pick up oxygen; 13 ref to wall of capillary being thin; 14 ease of / rapid, gaseous exchange or short diffusion pathway; smooth muscle 15 adjust size of airways (in, exercise / asthma); connective tissue / elastin / elastic tissue 16 stretch (inhalation); 17 prevents alveoli bursting; 18 recoil; R contract 19 helps exhalation / forces air out (of lungs); squamous epithelium / described 20 alveolus wall thin; 21 ease of / rapid, gaseous exchange or short diffusion pathway; 22 AVP; e.g. ref to large surface area of numerous alveoli 23 AVP; ref to macrophages removing pathogens

Question 44

Features of xylem and how they help with function

Answer 44

lack of contents / no cytoplasm / hollow / lumen / continuous / less resistance to flow / more space linked to idea of lack of contents thickening / rings / spirals / lignin (in the wall); treat cellulose as neutral prevents collapse / gives support / adhesion of water; pits / AW; A pores / holes (in side walls) allow lateral movement / AW;

Question 45

Example in plants of a source

Answer 45

leaf / storage organ / named storage organ

Question 46

Example in plants of a sink

Answer 46

root / tuber / storage organ / (young) growing region / leaf | qualified / flower / bud / fruit / seed;

Question 47

explain how mass flow of materials between the source and the sink would be brought about

Answer 47

``` water will enter source; by osmosis; down / AW, a water potential gradient; increase in (hydrostatic) pressure; as source / sink cannot expand / AW; force / AW, solution along (tube to sink); AVP; e.g. explanation of mass flow ```

Question 48

piece of evidence for the involvement of an active process in sugar transport from sources to sinks in plants

Answer 48

ATP involved / respiration involved / many mitochondria in companion cells / reduced by metabolic inhibitors / oxygen dependent / temperature dependent / loading against a concentration gradient

Question 49

Describe an active mechanism which could possibly be involved in the transport of sugars from sources to sinks.

Answer 49

``` loading, into companion cell / from transfer cell / into sieve tube / into phloem – implied; H ions / protons, pumped out of, companion cell / sieve tube / phloem; diffuse back in with sucrose; protein carrier / co-transporter; possible active unloading by reverse mechanism; AVP to cover alternative mechanisms;;; e.g. electro-osmotic theory K+ pump via companion cell electrochemical gradient sieve pores provide a capillary bed ```

Question 50

Definition: double circulatory system

Answer 50

(blood flows) twice through the heart / AW; for one circuit / cycle (of the whole body) / AW; A for one heart beat ref pulmonary and systemic systems / to lungs and to (rest of) body;