Biology Past Papaers

Front 1

The curve is steepest in the region marked X on the graph. Explain how the steepness of thecurve in region X helps the tissues in a mammal function more efficiently.

Back 1

small drop of ppO2 (dont do this in exam)

large amount of oxygen dissociates easily

tissues can respire aerobically

aerobic respiration more efficient

than anaerobic (prevents lactic acid build up)

Front 2

What is the advantage of an increasing partial pressure of carbon dioxide in a muscle?

Back 2

more oxygen released

at same partial pressure of oxygen

needed for aerobic respiration

Front 3

Explain the importance of the position of the dissociation curve of fetal haemoglobin

Back 3

higher affinity of oxygen; absorbed from mother

becomes fully saturated at low ppO2

Front 4

. Explain howthis curve indicates the worm’s adaptation to its environment.

Back 4

lives in environment where low ppO2

allows Hb to become fully saturated at lower ppO2

Front 5

Xylem vessel

Back 5

transports water/ mineral ions

Front 6

sieve tube element

Back 6

Transport of organic molecules/SUCROSE/ amino acids/ products of photosynthesis

not glucose

Front 7

Companion cell

Back 7

Makes proteins/ ATP/ release energy

not make/ produce energy

Front 8

function of lignin?

Back 8

supports/ strengthens/ prevents

xylem vessel from collapsing when water sucked along it

adhesion of water molecules

aids movement of water upwards

Front 9

Movement of water

Back 9

Water is absorbed into the root mainly through the root hairs. Its movement through theapoplast is prevented by the Casperian strip in the endodermis. Movementthrough the symplast pathway is aided by the plasmodesmata. The water is pulledupwards by the transpiration pull and this is possible by large cohesive forces between the water molecules and adhesion forces between the watermolecules and the hydrophilic lining of the cells.

Front 10

Give three other properties of respiratory surfacescommon to all organisms.

Back 10

short diffusion pathway

large surface area

permeable

moist

concentration gradient

Front 11

respiratory surface in inseccts

Back 11

tracheole in contact with tissue

Front 12

Advantages of using a tracheal system for gas exchange

Back 12

fast (oxygen 200,000 x faster than blood)
no respiratory pigment; reduced water loss

oxygen supplied directly to tissue; no transport system required

Front 13

Describe and explain the process of inspiration in a mammal.

Back 13

intercostal muscles contract

ribs upwards and outwards

diaphragm contracts/ flattens

volume increases

pressure decreases

below atm pressure

(air drawn in)

Front 14

State the difficulties aquatic organisms face, compared to terrestrial organisms, inobtaining oxygen from water.

Back 14

water contains less oxygen than air

diffusion rate slower

dense/ viscous medium more difficult to pump

Front 15

why is countercurrent flow more efficient

Back 15

concentration gradient maintained over entire distance travelled by water over gills

Front 16

suggest two reasons why terrestrial animals rely on internal fertilisation

Back 16

increased chance of fertilisation

gametes independent of water for movement

fertilised egg can develop inside protective layer

gametes dont dehydrate

Front 17

advantages of sexual reproduction

Back 17

variation

allows a development of a resistant stage in lifecycle

seeds, spores, larvae allow dispersal

Front 18

cons of sexual reproduction

Back 18

slow form of reproduction (needs two individuals)
some variations not as successful as parent type/ mutations more common

Front 19

Suggest three reasons why the flowering plants have been so successful in the colonisationof the land.

Back 19

life cycle rapid; food store in seed allows rapid growth of embryo; enables to survive long periods of time

protection by resistant outer layer

leaf fall, recycling of nutrients, link with animals, no need of water for fertilisation

Front 20

describe theory of evolution as put foward by Charles Darwin

Back 20

Darwin recognised species evolved over time

explain adaptive radiation

evidence= similar morpholgically to common ancestor

similar proteins

so similar DNA

fossil evidence

Front 21

what is ventilation

Back 21

the process of moving the respiratory medium over the respiratory surface

Front 22

What organelles are present in guard cells but not in the other epidermal cells ofa leaf

Back 22

chloroplasts

Front 23

Explain the mechanism by which light causes the opening of stomatal pores.

Back 23

potassium ions pumped into guard cell

by active transport

starch to malate

WP in guard cell decreases

water moves in by osmosis down WP gradient

turgor increases, as cells expand, they bend as inner walls thicker than outer

Front 24

What environmental factor could account for the displacement of the curve fromA to B

Back 24

increased carbon dioxide

Front 25

significance of Bohr shift

Back 25

oxygen dissociates more easily at lower ppO2

Front 26

why are llamas curve to left of human?

Back 26

at low partial pressures of oxygen

Hb has greater affinity to oxygen

able to absorb more oxygen from environment

Front 27

how are homologous structures used as evidence for evolution

Back 27

suggest shared common ancestory

Front 28

advantage of asexual reproduction

Back 28

colonise area quickly

Front 29

internal fertilisation

Back 29

fusion of gametes

with femal body

using intromittent organ

no reference to zygote

Front 30

mode of nutrition

Back 30

herbivore

carnivore

Front 31

Describe how the stomach of P is adapted to its diet (ruminant)

Back 31

cud mixed with ceullulase secreting bacteria

allows cud to be regurgitated and further chewing

allows water to be re-absorbed

rumen=1st chamber, hosts microorganisms

some absorption of fatty acids

Front 32

Suggest why certain areas of carnivores stomach are larger

Back 32

to provide room to store meat

until killing of prey next time

long time between feeding...

Front 33

blood vessels in sub mucosa

Back 33

transport dissolved products of digestion to liver (via hypatic portal vein)

Front 34

lymphatic vessels in sub mucosa

Back 34

transport lipids

Front 35

nerves in s.m.

Back 35

coordinates muscular contraction for peristalsis

control secretion

Front 36

brunners glands

Back 36

secretion of enzyme

Front 37

state best technique for working out the relationships between the descendants ofthe orignal finch

Back 37

comparing DNA

(DNA hybridisation) cytochrome C

not gel electrophoresis

Front 38

In a similar diagram of a human gut these features would be intermediatebetween those shown. Give a reason for this

Back 38

humans omnivores

Front 39

Suggest a reason for refection

Back 39

gives more time to absorb nutrients (eat poo)

Front 40

Cows feed in a similar way to rabbits but do not show refection.Explain this difference.

Back 40

cows have four more stomachs

food is regurgitated for chewing of cud

additional stomachs for fermentation

Front 41

Name three structural features of fish gills which make them efficient gaseous exchangeorgans

Back 41

large surface area

thin

permeable

good blood supply

Front 42

advantage of countercurrent flow

Back 42

concentration maintained along whole of gill plate

blood saturation reaches higher level

Front 43

Describe the function of the hydrogen ions produced in the red blood cell andexplain its importance in muscle tissue

Back 43

dissociate oxygen from oxyhaemoglobin

needed for aerobic respiration by muscle

Front 44

explain function of chloride shift

Back 44

to maintain electrical neutrality of rbc

Front 45

Describe and explain the difference in the transpiration rate at 0800hrs compared with1600hrs

Back 45

increased rate of transpiration

increased temperature/ other factor

not light

Front 46

what is meant by cohesion?

Back 46

strong attraction of water molecules exert on one another

Front 47

what creates tension

Back 47

water evaporating through stomata at top of column are replaced from below

and because of cohesion, this creates an upward force (tension) throughout the column

Front 48

how is root pressure generated?

Back 48

active transport of ions into root xylem

water drawn in by osmosis at foot of xylem

osotic pressure

Front 49

What is the role of the intercostal muscles in the thorax of a mammal?

Back 49

move ribs/enlarge thorax

Front 50

Give two advantages to a mammal of having internal lungs

Back 50

reduce heat loss

reduce water loss

protection (by ribs)

Front 51

where are villi present?

Back 51

duodenum

ileum

Front 52

where is the site of mechanical breakdown of food

Back 52

mouth

stomach

Front 53

what connects with the bile duct?

Back 53

duodenum

Front 54

where do microorganisms secrete vitamins?

Back 54

large intestine

Front 55

where does carbohydrate digestion tak eplace?

Back 55

mouth

duodenum

illeum

Front 56

where are brunners glands found

Back 56

duodenum, secrete alkaline fluid

Front 57

main region of water absorption

Back 57

large intestine

Front 58

where does protein digestion begin

Back 58

stomach

Front 59

visible features anthropods have in common

Back 59

exoskeleton

jointed limbs

segmented body

Front 60

significance of myoglobing

Back 60

oxygen store

high affinity to oxygen

used when muscle is working very hard

Front 61

how do parasties survive without a digestive system?

Back 61

absorption of host nutrients

over parasites body

Front 62

why do parasited produce large numbers of offspring

Back 62

high mortality

Front 63

what is meant by term source

Back 63

region where photosynthate produced

Front 64

sink?

Back 64

region where photosynthate used

Front 65

importance of closure of spiracles

Back 65

prevents excessive water loss

Front 66

explain lifcycle of parasite

Back 66

eggs eaten by pigs

tapeworm eggs in muscle

undercooked meat eaten, containing eggs

Front 67

explain why cynaide prevents stomatal pores from opening

Back 67

cynaide is a respiratory inhibitor (stops ATP)

prevents active transport of potassium ions into guard cell

Front 68

stae and explain adapatations of hydrophytes

Back 68

large air spaces for buoyancy

stomata on upper surface to allow gas exchange with air

thin cuticle as little water vapour loss

little xylem as surrounded by water

air spaces in stems allow diffusion of gases

Front 69

why does aortic pressure not reach 0

where as ventricle does

Back 69

aortic (semilunar) valve closes

preventing backflow

ventricle diastole

Front 70

how does hydrolysis of lipds increase ph

Back 70

xreates fatty acids

increase pH

Front 71

main sites of digestion?

Back 71

mouth

stomach

small intestine

Front 72

main sites of absorption?

Back 72

small intestine

large intestine

Front 73

explain why human digestion system is divided into specialised regions

Back 73

diffwewnt regions carry out differnt function (enzyme optima)...

Front 74

parasite

Back 74

lives in or on another organism

deriving benefit

whilst causing harm to host

Front 75

describe one theory that would explain how water moves up stem of leafy shoot

Back 75

water vapour lost from leaves by transpiration

causes tension on water molecules

cohesive forces between water molecules

adhesive forces between water molecules and xylem vessels

water molecules pulled up xylem vessel

Front 76

explain full reasons for max and min pressure in left ventricle and aorta

Back 76

contraction of left ventricle causes a surge in blood pressure

pressure drops when left ventricale relaxes

pressure in aorta does not decrease to zero as of closing of aortic, semi lunar valves

elastic recoil of arteries maintains blood pressure

Front 77

role of lymph vessel

Back 77

remove excess tissue fluid

Front 78

autotrophs

Back 78

Autotrophs use {(simple) inorganic molecules / carbon dioxide andwater} to synthesise {(complex) organic compounds / named organiccompound

eg Plant / named Plant / Algae / Bacteria must be qualified bychemosynthetic;

Front 79

saprobiants

Back 79

Saprobionts {secrete enzymes onto the food outside the body / feedby extracellular digestion} and absorb ( or e.q.) the (soluble)products (by diffusion); NOT ingestBacteria / Fungi / or named

Front 80

vessels found on surface of heart?

Back 80

Coronary;Supplies oxygen / blood to the heart muscle / wall / tissue / cells ORcorrect function for vein;

Front 81

valves replacement

Back 81

Valve {exposed to / works at} a higher pressure (in left ventricle)/{Right ventricle pumps blood at / valve A exposed to} lowerpressures (to lungs);

Front 82

what would happen to flow of blood if valve is damaged?

Back 82

Blood leaks back (from ventricle) to atrium

) Breathlessness

Front 83

how do fish overcome problem of water?

Back 83

Water is forced over the gill by {ventilation mechanisms / pressuredifferences / continuous swimming};Unidirectionally / one way flow;Countercurrent flow of blood and water / or description of;{Diffusion / concentration} gradient is maintained or description of;over the entire gill surface;High affinity Hb;

Front 84

importance of epithelium?

Back 84

Microvilli:Increase SA for diffusion / uptake of molecule / digestion (ofmolecules);11Mitochondria:(Synthesis of) ATP for active transport;

Front 85

explain how endodermis carries out its function of uptake of water and mineral ions into plant

Back 85

Waterproof / Casparian strip / band / suberin;Blocks the apoplast pathway;Selective uptake / Active uptake / transport of minerals (byendodermis cells);Into symplast pathway;Active transport of minerals into pericycle;Water follows by osmosis;Water and minerals move into xylem vessels;

Front 86

Describe three properties that all respiratory surfaces must possess and explain whythey must have them.

Back 86

Thin – small diffusion distance;Accept small diffusion distance/ pathwayLarge surface area- (large contact with air) for diffusion/ gasexchange/ OWTTE;Moist- allow gases to dissolve/ gases go into solution (to crossmembrane); Not diffuse intoPermeable-to allow gases to pass through (the respiratorysurface);NOT blood supply

Front 87

Give two reasons why gills do not function effectively on land.

Back 87

They dry out/ unable to remain moist/ lose water; 2They clump together (because of surface tension.)/ collapse/lie on top of each other;

Front 88

State the function of(i) sieve tube cells [1](ii) companion cells.

Back 88

{Translocation/ movement/ transport/ carry NOT flow} of{products of photosynthesis/ sucrose/organic compounds/sugars/ amino acids}/ description of source to sink/translocation;1(NOT nutrients/ other named sugar/ named ions)(ii) Carry out {metabolism/respiration} /to supply (sieve cells) with{energy/ATP}/ contain mitochondria for {ATP/ active transport};NOT contain organelles that the sieve cells do not have/ notloading sieve cell

Front 89

Describe two features of an amniote egg

Back 89

Fluid filled cavity (surrounded by a membrane);{Protective/ hard/ leathery} {shell/ outer covering/ coat};(embryo within) yolk sac/ food store/ yolk for nutrition/ owninternal nutrient supply;

Front 90

The development of embryos takes place internally in mammals. List three ways inwhich this is an advantage over externally laid eggs.

Back 90

(the young are retained) for a {considerable/ longer} time in themother’s womb or uterus;(The embryo is) nourished there from {the mother’s bloodsupply /the placenta}/ {unlimited nutrients/ OWTTE};Protection – qualified;The young are {born in a relatively advanced state ofdevelopment/ well developed/ more advanced growth inwomb}; [Any 3]NOT parental care/ ref to number of offspring

Front 91

Give an account of the sequence of events that takes place during the digestionand absorption of a meal containing carbohydrate and protein.

Back 91

n buccal cavity/ mouth;B teeth (and tongue) {mechanically/ physically} break down food/to provide large surface area;C (Saliva added from) salivary glands;D (saliva) contains mucus to lubricate;E Amylase substrate is starch, product is maltose/ disaccharides;F Stomach adapted for protein digestion/ protein digestion{starts/ begins} in stomach/ proteins are partially digested inthe stomach;G Produces hydrochloric acid/ low pH in stomach;H Peptidase/Pepsin’s substrate is {protein/ polypeptides},products are {polypeptides/peptides};reject ref to other enzymesI Small intestine (is adapted to) completes (protein/carbohydrate) digestion/ Description of {disaccharide/polpeptide} digestion in small intestine;J Named enzyme produced by small intestine;K Two named enzymes produced by pancreas;L correct reference to endo- exo- peptidases;M Absorption takes place in the ileum/small intestine;N Villi / microvilli increase surface area;O Glucose/ monosaccharides/ products are absorbed bydiffusion and active transport;

Front 92

Name the original source of energy that moves water through a plant.

Back 92

sunlight

Front 93

where is the main site of lipase production

Back 93

pancreas

Front 94

Explain how the jaw and teeth shown above are adapted for this mode ofnutrition herbivore

Back 94

{large/ridged/WM shape} {molars/premolars} for grinding;{diastema/space with no teeth/ gap between teeth} toassist with {chewing/ (tongue to) manipulate food/ cud};{well developed/ sharp/ long} incisors for {biting/ cutting/slicing/ tearing} (vegetation);loose articulation/ jaw moves in a {horizontal/ circular}plane;3maxVery small/ no canines;open roots to allow continuous growth of molars;

Front 95

Explain how the gut of this mammal is adapted for digestion.

Back 95

Four chambered stomach (NOT four stomachs) / rumen/large caecum;Contain cellulose digesting bacteria/ have cellulaseproducing bacteria; NOT cellulose eating bacteriaLong gut {to allow extra time for digestion of cellulose/cellulose harder to digest};Cud is regurgitated for further chewing;