B3.1 + B3.2

Question 1

Define gas exchange

Answer 1

exchange of oxygen and carbon dioxide between the alveoli and bloodstreams (passive diffusion) through a permeable membrane

Question 2

Gas Exchange process for blood (4)

Answer 2

oxygen in air taken to alveoli in lungs

diffuses into the blood in capillaries

CO2 from blood diffuse into alveoli

CO2 expelled out of lungs

Question 3

Features of Gas Exchange (5)

Answer 3

permeable membrane

large SA - faster diffusion

ventilation to keep surface moist

thin walls for short diffusion distance

concentration gradient

Question 4

Permeability as a feature of gas exchange

Answer 4

must allow substances (O2, CO2) to pass through

Question 5

High SA:V ratio as a feature of gas exchange (2)

Answer 5

large respiratory surface for diffusion

enough SA for gas exchange per volume of air

Question 6

Moisture as a feature of gas exchange (2)

Answer 6

O2 + CO2 must dissolve in water/solution before diffusion

respiratory system is moist with water

Question 7

Thin layer as a feature of gas exchange (2)

Answer 7

thin to minimise diffusion distance

molecules can diffuse faster with shorter distance

Question 8

High concentration gradient as a feature of gas exchange (2)

Answer 8

larger concentration gradient = faster rate of diffusion

concentration gradient required for gas exchange/diffusion to function

Question 9

Respiration for maintaining concentration gradient in gas exchange (4)

Answer 9

cell respiration uses oxygen + produces CO2

O2 concentration lower inside cell than outside

CO2 concentration higher inside cell than outside

concentration gradient allows O2 from blood to enter cell + CO2 from cells to escape to blood

Question 10

Root hair cells in maintaining concentration gradients (2)

Answer 10

root hairs that increase surface area

for water intake

Question 11

Capillaries in maintaining concentration gradients (2)

Answer 11

walls of capillary - one cell thick (short diffusion distance)

constant flow of blood

Question 12

Fish gills in maintaining concentration gradients (3)

Answer 12

directly extract oxygen from water

capillaries located in gills

oxygenated blood flows separately from deoxygenate blood

Question 13

Define ventilation (3)

Answer 13

involves physical movement of air into and out of lungs

inhalation allows blood to become oxygenated

exhalation removes CO2 in blood

Question 14

Adaptations of mammalian lungs (3)

Answer 14

maximise surface area through alveoli

pneumocytes

alveoli surrounded by capillaries

Question 15

Relationship between pressure and volume (2)

Answer 15

inversely proportional

pressure increases as volume decreases

Question 16

Pressure and volume changes during inspiration (3)

Answer 16

volume of chest cavity increases

lowers pressure inside lungs (lower pressure compared to outside)

pressure wants to reach equilibrium so air enters in

Question 17

Pressure and volume changes during expiration (3)

Answer 17

volume of chest cavity decreases

higher pressure inside lungs

pressure wants to reach equilibrium so air exits

Question 18

Features of diaphragm (3)

Answer 18

muscle that forms “floor” of lungs

inhalation - contracts/flattens to increase volume of chest cavity + abdominal muscles relax

exhalation - relaxes (dome shape) to decrease volume of chest cavity + abdominal muscles contract

Question 19

Features of external intercostal muscles (3)

Answer 19

contract during inhalation

lifts ribs up and out to increase volume

internal intercostal muscles relax

Question 20

Features of internal intercostal muscles (3)

Answer 20

contract during exhalation

ribs pulled in and down to decrease volume

external intercostal muscles

Question 21

Define ventilation rate (2)

Answer 21

number of inspiration-expiration

spirometry used

Question 22

Define tidal volume

Answer 22

volume of air that moves in and out of lungs during normal breath cycle

Question 23

Define vital capacity

Answer 23

maximum amount of air a person can exhale from their lungs

Question 24

Inspiratory reserves

Answer 24

volume of air that can be inhaled forcefully after a normal breath

Question 25

Expiratory reserves

Answer 25

volume of air that can be exhaled forcefully after a normal breath

Question 26

Direction of gas exchange in leaves (2)

Answer 26

O2 enters through stomata CO2 exits out of stomata

Question 27

Waxy cuticle of leaf (2)

Answer 27

protects leaf prevents water loss without preventing entrance of light

Question 28

Upper epidermis of leaf (2)

Answer 28

thin + transparent allows light to reach palisade mesophyll cells

Question 29

Palisade mesophyll of leaf

Answer 29

absorbs light + carries out photosynthesis

Question 30

Spongy mesophyll of leaf (2)

Answer 30

contains air spaces allows gases to diffuse through leaf

Question 31

Stomata of leaf (2)

Answer 31

control water + gas exchange by opening/closing guard cells regulate size of stoma

Question 32

Define transpiration

Answer 32

loss of water by leaves through evaporation

Question 33

Structure of haemoglobin (3)

Answer 33

2 alpha + 2 beta polypeptide chain globular protein of 4 packed polypeptide chains conjugated protein - contains protein + iron

Question 34

Allosteric binding of haemoglobin (4)

Answer 34

O2 binds to haem group causes confirmational change that increased affinity of other haem groups binding of oxygen makes it easier to bind to more oxygen loss of oxygen makes it easier to lose oxygen

Question 35

Allosteric binding of oxygen to haemoglobin in alveoli (2)

Answer 35

high concentration of oxygen in alveoli easier for oxygen to bind quickly

Question 36

Allosteric binding of oxygen to haemoglobin in cells to respire (2)

Answer 36

low concentration of oxygen in alveoli easier for oxygen to disattach from haem groups

Question 37

CO2 binding to haemoglobin in red blood cells (Bohr Shift)(2)

Answer 37

binds to polypeptide region not haem group changes affinity of haemoglobin for oxygen - causes oxygen to be dissociated

Question 38

Bohr effect on oxygen dissociation curve

Answer 38

sigmoidal curve shifts to the right

Question 39

Fetal haemoglobin vs Adult haemoglobin (2)

Answer 39

fetal haemoglobin have gamma + alpha subunits fetal haemoglobin have greater affinity to oxygen

Question 40

Define tissue fluid (3)

Answer 40

fluid by which substances are exchanged between blood + cells supplies tissues with essential solutes made up of substances small enough to escape through capillary gaps (e.g oxygen, glucose, water, amino acids, fatty acids)

Question 41

Define capillary exchange

Answer 41

process by which substances move between blood and tissue fluid

Question 42

Single circulatory system (2)

Answer 42

blood flows through the heart in a single pathway e.g for fish

Question 43

Double circulatory system

Answer 43

2 separate pathways for oxygenated + deoxygenated blood

Question 44

Double circulatory system for mammals (2)

Answer 44

allows animals to be more active blood can reach respiring tissues due to greater pressure

Question 45

Double circulatory vs single circulatory (4)

Answer 45

single has 2 chambers while double has 4 chambers single - blood passes once, double - blood passes twice double - blood returns back to heart single - fish, double - mammals + humans

Question 46

Cardiac muscles as adaptations of the heart (3)

Answer 46

muscle of heart myogenic - no need for nervous stimulation continuous rhythmic action

Question 47

Aorta (2)

Answer 47

left-hand side of heart (ventricle) main artery where oxygenated blood leaves heart

Question 48

Vena Cava

Answer 48

main vein of heart where deoxygenated blood reaches right side of heart

Question 49

Myogenic contraction (3)

Answer 49

sinoatrial node contracts --> sends out electrical signal through walls of heart electrical signals travel through connections of fibres impulses travel to atrioventricular node

Question 50

2 Phases of Cardiac Cycle (2)

Answer 50

systole - atrial sytole, ventrical systole (contraction) diastole - atrial diastole, ventrical diastole (relaxation)

Question 51

Atrial Systole (2)

Answer 51

last about 0.1 sec both atria contract - force blood from atria into ventricles

Question 52

Ventricular Systole (2)

Answer 52

ventricles contract - blood forced to the lungs + body pressure increases in aorta + pulmonary artery --> semilunar valves open + blood ejects

Question 53

Atrial Diastole (2)

Answer 53

AV valves open when pressure in ventricles > atria atria relaxes --> blood can flow in

Question 54

Ventricular Diastole