1
Q
explain why a low protein diet would result in fluid retention in the tissues [4]
A
- low protein diet reduces (plasma protein/albumin) levels
- plasma proteins reduce water potential of blood
- (lack of protein) water potential of plasma becomes higher
- decreases water potential gradient
- so less WATER reabsorbed / more WATER remains in tissue fluid / WATER moves out of the blood into the tissue fluid
2
Q
state what is meant by the term transpiration [2]
A
- loss of water VAPOUR / EVAPORATION of water
- from (surface of) leaf / through stomata
3
Q
state some practical measures which should be taken when setting up the apparatus to ensure the potometer functions correctly. give reasons
A
- shoot cut under water/ assemble under water
- to prevent air entering / bubbles
- shoot with large number of leaves
- to ensure measurable rate of transpiration
- avoid wetting leaves / ensure leaves are dry
- reduces rate of transpiration
- leave time for apparatus to settlr down
- allow plant to adapt to new conditions / to equilibriate
- seal joints with vaseline
- to prevent air entering apparatus/ prevent leakage
- ensure bubble set at an appropriate position / right hand end
- to enable a (suitable) reading to be taken
4
Q
water passes through the xylem of the root and stem of a plant before reaching its leaves.
name the original source of energy that moves water through a plant [1]
A
sun (light)
5
Q
explain how water moves up the xylem [2]
A
- molecules of water moving together / water pulled up
- because COHESION of MOLECULES
- ADHESION to (walls of) XYLEM/hydrophilic lining/vessel wall
- root pressure (forces/pushes) water upwards
6
Q
explain how its possible to tell that a diagram is of a root and not a stem [2]
A
- (xylem/vascular TISSUE) is at the center / xylem is star shaped / central stele) NOT BUNDLE
- no vascular BUNDLES / peripheral vascular BUNDLES in stem
- endodermis visible in root / no pith
7
Q
state the function of the atrio-ventricular node (AVN) on the functioning of the heart [2]
A
- (COLLECTS/RECEIVES) (wave of excitation/impulses) FROM SAN (not signal)
- passes on to (Purkyne fibres / Bundle of His)
- allows delay before wave passed to ventricles / stops atria and ventricles contracting at the same time
8
Q
state the function of the bundle of His and Purkyne fibres on the functioning of the heart [2]
A
- conducts wave to (base/apex) of ventricles/heart
- endures contraction (from base) upwards
9
Q
name what blood vessel is found on the surface of the heart and explain their function [2]
A
- coronary
- supplies oxygen / blood to the heart muscle / wall / tissue / cells
10
Q
explain why the bicuspid valve often has to be replaced because it ceases to work effectively and why the tricuspid valve rarely needs replacing [1]
A
- valve (exposed to/works at) a higher pressure (in left ventricle)
- (right ventricle pumps blood at / tricuspid exposed to) lower pressures (to lungs)
11
Q
what would happen to the flow of blood if the tricuspid and bicuspid valves are damaged? [1]
A
blood leaks back (from ventricle) to atrium
12
Q
suggest a symptom a person with a failing bicuspid valve may have? [1]
A
breathlessness / fatigue / rapid or irregular heartbeat / lower bp
13
Q
what do sunken stomata on xerophytes mean?
A
it can trap water vapour - decreasing concentration gradient
14
Q
describe and explain the role of the endodermis in the uptake of water into the xylem vessels and in generating root pressure [4]
A
- casparian strip / suberin
- blocks apoplast pathway / forces water into symplast pathway
- the (endodermal cells / pericycle) ACTIVELY TRANSPORT IONS INTO THE XYLEM VESSELS
- this lowers water potential in xylem
- causing water to move INTO XYLEM BY OSMOSIS
- producing hydrostatic pressure (forcing water upwards)
15
Q
if the growing point of a shoot of a plant is removed, there is a greater accumulation of sucrose. explain why [2]
A
- sucrose used for (cell wall formation / cell division / mitosis / respiration)
- (less/no) sucrose used (by growing areas / sinks as they have been removed)
- therefore more will pass down stem
16
Q
-describe how carbon dioxide is transported from respiring tissues to the lungs [6]
- explain how changes in carbon dioxide concentrations in the blood can lead to an increased oxygen supply for respiring tissues [4]
A
- (some) CO2 (DISSOLVED directly / IN SOLUTION) in the plasma
- some CO2 (diffuses into/absorbed by) red blood cells
- some CO2 combines with haemoglobin/to form carbamino (haemoglobin/compounds)
- (most) CO2 combines with water to give carbonic acid
- catalysed by carbonic anhydrase
- carbonic acid dissociated into hydrogen carbonate and hydrogen ions
- hydrogen carbonate ions pass out (into plasma)
- (chloride shift) allows movement of Cl- into rbc
- to maintain (electrical / electrochemical) neutrality
- INCREASED (conc/partial pressure) of CO2 (dissolved in blood)
- lowers pH of blood / blood becomes more acidic
- oxyhaemoglobin (accepts H+/acts as a buffer)
- reduces AFFINITY of haemoglobin for oxygen
- MORE oxygen is released (from oxyhaemoglobin) / MORE oxyhaemoglobin dissociates
- oxygen dissociation curve moves to the right / Bohr (shift/effect)
17
Q
describe the similarities and differences in the structure and functioning of arteries and xylem vessels [10]
A
- both are tubular / contain a lumen
- both have movement by mass flow
- both movement along pressure gradients
- both movement in one direction only
- artery transports blood, xylem water
- movement of liquid pulsatile in arteries, smooth in xylem
- xylem vessels contain lignin
- xylem has support function
- (adhesive forces/hydrophilic lining) in xylem
- arteries have (muscle / elastic tissue)
- arteries recoil
- smooth endothelium of artery / endothelium reduces friction
- artery WALLS composed of layers
18
Q
if the pH of the blood became more acidic, the position of the dissociation curve for e.g a mouse would change. how?
and explain the benefits to the mouse of this change in position [4]
A
- shift to right
- (move to right) lowers affinity of HAEMOGLOBIN for oxygen
- MORE oxygen released / oxygen MORE readily dissociates
- at the same partial pressure of oxygen
- for (aerobic) respiration
19
Q
suggest why the end of the shoot should be cut under water before being inserted into the potometer [2]
A
- prevent formation of air bubble in XYLEM / entry of air into XYLEM
- which would break (transpiration stream/cohesive forces) / block movement of water
20
Q
state what measurements would have to he made, in order to determine the rate of transpiration [2]
A
- diameter of capillary tube
- distance travelled by bubble
- time taken
21
Q
what are 4 types of cell that are found in phloem tissue?
A
- companion cell
- sieve tube element
- (phloem) parenchyma
- (phloem) fibres
22
Q
explain how the features of sieve tube element enable the phloem to carry out its function [4]
A
- presence of SIEVE plates/pores
- permits bidirectional flow/permits flow (from cell to cell/ through plant)
- (few/no) organelles
- no obstruction to flow of solutes
- plasmodesmata
- allows transport of (molecules/ATP/sucrose) from COMPANION CELL (to sieve tube element)
23
Q
the mass flow theory is one explanation to account for the movement of solutes in the phloem.
suggest why the presence of large numbers of mitochondria in the companion cells does not support this theory [3]
A
- mass flow is (a passive process / not an active process)
- from high to low (concentration/pressure) down a concentration gradient
- (mitochondria /energy/ATO) not required
24
Q
how is a root hair cell adapted to its function [1]
A
- has large s.a to absorb (water/minerals/ions)
- many mitochondria for active transport of minerals/ions
- thin cell wall for short diffusion pathway
25
water can travel across the root via the apoplast and symplast pathways. describe the difference between these two pathways [2]
- apoplast pathway = water travels though the cell walls
- symplast pathway = water travels through the cytoplasm AND plasmodesmata
26
name the leaf tissue where radioactive C-14 is incorporated into organic molecules [1]
palisade / spongy / mesophyll
27
cardiac muscle is said to be myogenic (spontaneously active). what does this term mean [1]
- can generate its own impulse/contraction / does not need to be stimulated by a nerve to make it CONTRACT
(- can contract without external nerve impulses)
28
explain how blood is prevented from flowing from left ventricle to the left atrium [2]
- the (atrio-ventricular valves/bicuspid) close (preventing backflow of blood)
- when the pressure in the ventricles exceeds the pressure in the atria / during ventricular systole/contraction
- tendons prevent valves inverting
29
the events occurring during the beating of a human heart are called the cardiac cycle. in an average adult heart, there are approximately ____ cycles per minute
70
30
mammals have a double circulation.
state what is meant by the term double circulation and explain its advantages to a mammal [3]
- blood travels through heart twice during one complete circuit
- separates (pulmonary/to lungs) and (systemic / to body)
- circulations
- maintains high blood pressure (to body)
- rapid circulation of blood
- no mixing of oxygenated/deoxygenated blood
31
the atrio-ventricular septum is a thin layer of connective tissue between the atria and the ventricles.
explain the role of the atrio-ventricular septum and the AVN [4]
- prevents direct transfer of wave of excitation to ventricles / prevent atria and ventricles from contracting at same time
- allows time for ventricles to fill
- wave is picked up by AVN
- which transfers to bundle of His / purkinje / purkyne fibres
- causes contraction of ventricles from base
32
whats the name of the big pointy tooth on a carnivore
carnassial teeth
33
region 1 of a graph shows the blood pressure in the left ventricle (big squiggles), and region 2 shows the blood pressure in the aorta (smaller squiggles but still quite high pressure)
explain fully the reasons for the differences in the maximum and minimum blood pressure in the left ventricle and the aorta [3]
- contraction of left ventricle/ventricular systole causes a surge/increase in blood pressure
- pressure drops when the (left ventricle relaxes/ventricular diastole)
- pressure in aorta does not fall to zero because of the closing of the aortic/semi-lunar valve
- elastic recoil/elasticity of the arteries maintain blood pressure
34
why does the blood pressure decrease so rapidly as it travels through the arteries and through the body?
- friction / resistance with vessel walls
(- greater distance from heart)
35
explain how differences in the hydrostatic and osmotic pressures between the arterial and venous ends of the blood supply results in the formation of tissue fluid [3]
• at arterial end = hydrostatic pressure (forcing liquid out of capillaries) greater than the osmotic pressure (drawing water in)
• at venous end = hydrostatic pressure has decreased
- water potential gradient / high osmotic pressure in capillary or osmotic pressure greater than hydrostatic pressure causes inward flow
- not all water (re)absorbed into capillary
36
what is the function of the vessel carrying lymph fluid?
- drains/removes (excess) tissue fluid from all tissues / prevents build up of tissue fluid / returns (excess) tissue fluid to blood via lymphatic system
37
list four ways in which arteries differ in structure from veins [4]
- no valves
- small/narrow lumen
- more elastic in walls
- thick(er)/muscular walls/tunica media
- less collagen
38
explain the difference in blood pressure between the top of a squiggle and the bottom of one in an artery
- top = VENTRICULAR contraction/systole
- bottom = VENTRICULAR relaxation/diastole
39
explain why a contraction in the left atrium takes place a few milliseconds after that in the right atrium [2]
- SAN/pacemaker in wall of right atrium
- wave of depolarisation passes from here across atria
40
there is a layer of connective tissue between the atria and ventricles. what is the function of this tissue [2]
- prevents depolarisation in atria passing to ventricles
- therefore stopping ventricles contracting downwards
41
explain why, during periods of exercise, blood flow through the coronary arteries is increased? [4]
- increased oxygen
- increased glucose / nutrients
- remove carbon dioxide
- remove lactic acid
- aerobic respiration
42
what is the name given to the difference between two curves caused by a change in pH?
Bohr shift/effect
43
list two ways in which the shape of the haemoglobin dissociation line differs from the theoretical line [2]
- haemoglobin line is s-shaped
- actual line rises much more steeply in the middle
- theoretical line shows no flattening at top
- haemoglobin shows higher saturation throughout
44
the dissociation curve for myoglobin is to the left.
suggest how myoglobin can perform a useful function in muscle tissue. [3]
- myoglobin is saturated/ has high affinity for oxygen at very low pp
- acts as an oxygen store
- used when muscle is exercising heavily/working hard
45
explain what is meant by the terms source and sink [2]
- source = region where sugar/carbohydrate/photosynthate is produced and exported
- sink = region where photosynthate is used/stored
46
what is the name given to the transport of sucrose from the source to the sinks in a plant?
translocation
47
name the tissue and the type of cell where you would expect the greatest amount of radioactivity to be detected [2]
phloem and sieve tubes
48
state three adaptations of hydrophytes for living in an aquatic environment and state why each important [3]
- large AIR SPACES for buoyance/diffusion/floating
- stomata on UPPER surface so allowing gas exchange with the air
- thin cuticle as little water (vapour) loss
- little support tissue as buoyed by water
- little xylem as surrounded by water
- air spaces in stems allowing diffusion of gases
49
explain why leaves and chloroplasts change their orientation during the day [1]
- to increase/maximise absorption of light / so that greater surface area of leaves face the sun / long axis of chloroplasts is in same direction as light
50
water and minerals can follow several paths from the soil to the xylem. these are the apoplast, symplast and vacuolar pathways. both the symplast and vacuolar routes involve water crossing cell-membranes. explain why the vacuolar route is slower than the symplast pathway [2]
• vacuolar:
- water crosses more membranes than symplast / water moves in and out of vacuole / water has to pass through tonoplast/vacuolar membrane / water has to pass through vacuole and cytoplasm
• symplast:
- moves through cytoplasm and plasmodesmata / only crosses one membrane
51
xylem vessels and phloem sieve tubes are strengthened by different chemicals found in their cell walls. name these chemicals:
xylem?
phloem?
- xylem = lignin
- phloem = cellulose
52
explain why the narrowing of the coronary arteries could lead to the heart not contracting [2]
- oxygen/glucose does not reach cardiac/heart MUSCLE
- (muscle) unable to respire (aerobically) / less ATP produced
53
name the vessel that removes excess tissue fluid [1]
lymph (capillary/vessel) / lymphatic
54
explain why fluid will accumulate in the tissues of a person whose diet is poor in protein [3]
- fewer plasma proteins / not enough protein in blood
- which (raises/increases) (water/solute) potential of (plasma/blood) / osmotic pressure is too low
- reduces water/solute potential gradient / hydrostatic pressure is greater than osmotic pressure
- less water/fluid reabsorbed (by osmosis)
55
most plants are unable to survive in waterlogged soil because air spaces between soil particles become filled with water.
describe the pathways by which water passes from the cells of the epidermis across the cortex of the root and then into the vascular tissue of a plant growing in well-drained soil.
explain why a plant growing in waterlogged soil experiences a reduction in root pressure [9QER]
- apoplast + symplast + vacuolar pathway
- apoplast along cell walls
- symplast through cytoplasm/plasmodesmata
- vacuole pathway passes through tonoplast/cytoplasm
- down water potential gradient / by osmosis
- endodermis has Caspian strip
- waterproof/composed of suberin
- blocks apoplast pathway
- water forced/passed into symplast
- active transport of salt/minerals INTO XYLEM
- lowers water potential in xylem
- water enters xylem by osmosis/down water potential gradient
- less/no oxygen for respiration
- less/no respiration so less/no energy/ATP
- for active transport of minerals in the endodermis/root hairs
- lower water potential gradient as a result of less active transport of salt/minerals into xylem
- less water enter xylem which lowers root pressure
56
explain why a blockage of xylem vessels by (e.g a fungus) causes the wilting of leaves above the infection site and the death of the tree [4]
- xylem transports (water/minerals) from roots/UP the plant/to the leaves / xylem allows transpiration
- lack of water causes leaf/cells to lose turgor/become flaccid / cells become plasmolysed
- reduced surface area
- no/reduced photosynthesis/less water for photosynthesis
- less products of photosynthesis
- for respiration/growth
57
what are some features of the gut parasites that are adaptations to their parasitic way of life? [3]
- (suckers/hooks) (for attachment to host cell) / can embed deeply into walls / can’t be removed by peristalsis / egestion
- LARGE SURFACE AREA TO VOLUME RATIO
- (thin/flattened)(proglottids/segments)
- short diffusion pathway
- covering resistant to host’s digestive enzymes
- produces large number of eggs
- no digestive system / digested products in host gut absorbed into (tapeworm)
58
carnivorous teeth:
- large/pointed canines for tearing/grasping flesh / killing prey
- molars/premolars for cutting/slicing meat NOT tearing
- (small) incisors for gripping/stripping flesh
- CARNASSIALS teeth for (crushing /cutting)
- vertical movement of jaws
59
describe how the tapeworm is adapted to peristalsis in the human intestine [1]
- scolex/hooks and suckers + attach to gut wall
60
explain why the tapeworm does not need a mouth or alimentary canal [2]
- nutrients absorbed through its body surface (so it doesnt need a mouth)
- food is pre-digested (so doesnt need an alimentary canal)
61
suggest why the tapeworm relies on anaerobic respiration for its metabolism [1]
- oxygen levels are too low for aerobic respiration in the intestine/had a low metabolic rate and (does not require aerobic respiration/does not move much)
62
body wall cells of T.solium (parasite) have been observed to contain transmembrane proteins involved in active transport mechanisms. suggest how these mechanisms aid the survival of the parasite within its host [2]
- enable the worm to absorb ions/a.a/glucose/correct named product of digestion
- against concentration gradient
63
herbivore teeth:
- LARGE/RIDGED (MOLARS/PREMOLARS) for GRINDING
- DIASTEMA/space with no teeth/gap between teeth to assist with CHEWING/(tongue to)MANIPULATE FOOD/CUD)
- WELL DEVELOPED/SHARP/LONG incisors for BITING/CUTTING/SLICING/TEARING (vegetation)
- jaw moves in horizontal/circular plane
- no/very small canines
- open roots to allow continuous growth of molars
64
how is the gut of a herbivore adapted for digestion [2]
- four CHAMBERED stomach / rumen / large caecum
- contain/have cellulose digesting bacteria (NOT cellulose eating bacteria)
- long gut (to allow extra time for digestion of cellulose / cellulose harder to digest)
- cud is regurgitated for further chewing
65
what is the name of the structure in a villi that goes straight up a villi (not capillary networks)
lacteal/lymph VESSEL
66
what are two features of epithelial cells lining villi and explain why each is important for the cell to function efficiently [4]
- microvilli - increase SA for diffusion / uptake of molecules / digestion of molecules
- mitochondria - synthesis of ATP for active transport
67
what is the function of goblet cells in the intestine?
secretes/makes mucus
- lubricates/reduces friction (for passage of food)
- prevents (auto digestion of /digestion of / effect of acid/enzymes on) the gut wall
-
68
explain two features of a villi that are important in the functioning of the villus [4]
- microvilli - INCREASE/LARGE s.a / greater absorption/diffusion of digested products / increasing catalytic surface area for digestion
- large CAPILLARY NETWORK / good blood supply - transport/absorb glucose/a.a / maintain a diffusion/concentration gradient
- presence of lacteal/lymph vessel - absorb (lipids/fats/fatty acids)
- thin epithelium / epithelium one cell thick - short diffusion pathway
69
layers of smooth muscles are found in the wall of the small intestine. explain the role of these muscle layers in the process of digestion [3]
- peristalsis
- correct action of circular AND longitudinal muscles / wave of muscular contraction
- forces/pushes/propels food along/mixes food (for more efficient digestion/absorption)
70
amino acids are absorbed by capillaries and transported to the liver. describe the fate of the EXCESS amino acids absorbed [2]
- amino group removed
- (amino groups) to urea
- remainder to carbohydrate/glycogen
71
the liver produces bile which contains both bile salts and hydrogen carbonate ions.
use your knowledge of digestion, suggest a function of the hydrogen carbonate ions [1]
- OPTIMUM pH for enzymes / to NEUTRALISE stomach acid
72
where would the adult tapeworm be located in a human? why? [3]
- small intestine
- tapeworm lacks a digestive system
- the small intestine contains the products of digestion/digested nutrients / nutrients can simply be absorbed/diffuse across the tapeworm’s BODY SURFACE/MEMBRANE/skin
73
an experiment was carried out to determine the effect of bile salts on the
digestion of lipids. using full cream milk, phenolphthalein pH indicator, enzyme and sodium carbonate.
explain the change in colour of indicator from pink to colourless
- HYDROLYSIS of lipids/fats
- releasing fatty acids
- causing a more acid pH / reducing pH
74
an experiment was carried out to determine the effect of bile salts on the
digestion of lipids. using full cream milk, phenolphthalein pH indicator, enzyme and sodium carbonate.
suggest why the experiment was carried out using full cream milk
- more fatty acids / products
- quicker change in colour/faster reaction
75
some protease enzymes added to the model of a body are in the form of inactive precursors.
explain why these enzymes are not secreted in their active form? [1]
- to prevent (autolysis / self-digestion)
76
coeliac disease in humans is caused by a protein, gluten, found in wheat, barley and rye. it leads to a loss of villus height and a breakdown of microvilli.
explain why people with coeliac disease sometimes suffer from deficiency diseases [2]
- surface area reduced
- do not absorb substances so efficiently / reduced uptake
77
coeliac disease in humans is caused by a protein, gluten, found in wheat, barley and rye. it leads to a loss of villus height and a breakdown of microvilli.
explain the reduced efficiency of digestive enzymes, such as those involved with the final breakdown of dipeptides, in people with coeliac disease [1]
- no or fewer microvilli / surface areas reduced for enzyme action / catalytic surface reduced / enzymes absorbed onto membranes
78
explain why the tapeworm has a very simplified digestive system [3]
- absorbs digested products of host
- because it had a large surface area to volume ratio
- no need to digest own food
79
describe two ways in which food is broken down mechanically in the human alimentary canal? [2]
- teeth + reference to (chewing/grinding) /reference to role of tongue
- contraction of (stomach/gut) wall / peristalsis
80
pepsin and trypsin are enzymes involved in the digestion of proteins. both are secreted as inactive precursors. complete the table to give the names of the substances responsible for their activation:
pepsin —> precursor : pepsinogen :
trypsin —> precursor : trypsinogen :
activated by:
- pepsinogen = HYDROCHLORIC acid
- trypsinogen = enterokinase
81
Heliocobacter pylori is a species of bacterium that lives in the stomach and digests urea into alkaline ammonia. ammonia is toxic to epithelial cells lining the gastric pits (glands)
- suggest how infection with H.pylori can lead to the development of a peptic ulcer [3]
- less mucus produced (because cells are killed) / mucus lining destroyed
- more HCl/acid produced to compensate for neutralising action of NH3
- acid in food/HCl attack/damage/erode lining of stomach wall
- pepsin can cause self digestion/autolysis
82
what is the function of the mucosa?
contains glands that release secretions
83
what is the function of the submucosa?
contains vessels to transport products of digestion
84
what is the function of the muscle layer?
peristalsis / or description
85
where do microorganisms secrete vitamins in the human alimentary canal?
large intestine
86
… sample not representative
87
explain why the hydrostatic pressure decreases as the blood travels along the capillaries [2]
- (fluid/water) lost (from capillaries)
- increased (total) cross-sectional area / increased resistance/ reference to friction
88
suggest the significance of increased blood flow to the skin during exercise [1]
allows (excess/more) HEAT to be lost (from the body)
89
describe one similarity and two differences between the adaptations of Amoeba and Hydra for obtaining their nutrition [3]
(both heterotrophic)
- both holozoic / carry out internal digestion / ingest food
• amoeba:
- engulfs food using membrane / phagocytosis / endocytosis
- food taken into a vacuole
- intracellular enzymes
• hydra :
- captures ‘prey’ with tentacles
- food taken into a (gut/mouth)
- extracellular enzymes
90
what is meant by a closed circulatory system and explain its role in these animals [2]
- blood carried in vessels
- transports molecules / substances / materials TO/FROM exchange surfaces / cells
91
with the exception of shape, state two structural features of guard cells that are different from epidermal cells [2]
- chloroplasts
- unevenly thickened cell walls
as level biology
flashcards
Decks in class (13)
# Cards
-
1.1 chemical elements and biological compounds432
-
1.2 cell structure and organisation213
-
1.3 cell membranes and transport158
-
1.4 biological reactions are regulated by enzymes182
-
1.5 nucleic acids and their functions199
-
1.6 genetic information is copied and passed on to daughter cells115
-
2.1 classification and biodiversity104
-
2.2 adaptions for gas exchange157
-
2.3a adaptations for transport in animals214
-
2.3b adaptations for transport in plants135
-
2.4 adaptations for nutrition177
-
extra flashcards unit 1 + unit 2151
-
unit 2 specifically91
