TOPIC 3

Question 1

size and structure relationship with surface area

Answer 1

size increases SA:V decreases

Question 2

SA:V and the metabolic rate

Answer 2

as SA:V increases the metabolic rate decreases
rate of heat loss per unit of body mass increases
organisms require higher rate of respiration
to release enough heat to maintain a constant body temperature

Question 3

single celled organisms adaptations

Answer 3

thin flat shape and large surface area to volume ratio
short diffusion distance to all parts of the cell

Question 4

how are insect tracheal systems adapted for gas exchange

Answer 4

tracheoles have thin walls short diffusion distance to all cells
lots of branched tracheaoles so short diffusion distance and large surface area
tracheas provide tubes full of air so faster diffusion

Question 5

terrestrial insect S2F

Answer 5

thick waxy cuticle increase the diffusion distance so less water loss
spiracles can open and close to reduce water loss
hairs around spiracles that top moist air to reduce water loss

Question 6

gills adaptations

Answer 6

made of filaments veered in many lamellae to increase the surface area for diffusion
thin lamellae wall to increase rate of diffusion
lamellae have large number of capillaries rot remove o2 quick and bring co2 to maintain a concentration gradient

Question 7

counter current flow

Answer 7

blood and water flow in opposite directions over the lamellae so there is always a high concentration of oxygen in water than blood near maintaining a concentration gradient of oxygen between water and blood
for diffusion along the whole length of the lamallae

Question 8

leaf adaptations

Answer 8

many stomata for LSA for exchange
spongy mesophyll cells contain air spaces so a large surface area for gas to diffuse
thin so short diffusion distance

Question 9

alveolar epithelium adaptations

Answer 9

flattened cells for short diffusion distance
folded for a large surface area
most so gases can dissolve for diffusion
good blood supply from network of capillaries to maintain. a concentration gradient

Question 10

simple. gas exchange in lungs

Answer 10

oxygen diffuse from alveolar air spaces into blood down its concentration gradient
across the alveolar epithelium then across capillary endothelium

Question 11

inspiration

Answer 11

diaphragm contract so it flattens
external intercostal muscles contract
internal intercostal muscles relax so ribcage moves up and out
increasing volume and decreases pressure
so air moves into lungs down pressure gradient

Question 12

expiration

Answer 12

diaphragm relaxes down and in
internal intercostal muscles contract
external intercostal muscles relax
ribcage moves down and in
decreasing volume and increasing pressure in thorax activity
air moves out of the lungs down a pressure gradient

Question 13

why is expiration normally passive a rest

Answer 13

internal intercostal muscles don’t need to contract
expiration aided by elastic recoil in alveoli

Question 14

lung disease

Answer 14

thick alveoli so increase in diffusion distance
the alveolar wall breakdown so reduces the surface area
reaching lung elasticity
narrower airways reducing airflow

Question 15

why would people with lung disease experience fatigue

Answer 15

less oxygen so less aerobic respiration and less ATP made

Question 16

digestion of starch

Answer 16

amylase produced by salivary glands and pancreas hydrolyse starch to maltose
membrane bound maltose hydrolyse maltose to glucose
by hydrolysis of glycosidic bond

Question 17

digesting disacharides

Answer 17

membrane bond disaccharide hydrolyse disaccharides to two monosaccharides
by hydrolysing the glycosidic bond

Question 18

digestion of lipids

Answer 18

bile salts emulsify lipids to smaller droplets
increasing the surface area of lipids
lipase hydrolyse lipids to monoglycerides and fatty acids by hydrolysing the glycosidic bond

Question 19

protein digestion

Answer 19

exopeptidases hydrolyse the terminal amino acid by breaking peptide bond
endopeptidases hydrolyse peptide bond in the middle of polypeptide into smaller polypeptides
dipeptidases hydrolyse dipeptidases into 2 amino acids

Question 20

co transport

Answer 20

NA actively transported out epithelial cells lining into blood establishing a conc gradient of NA
Na enters the epithelial cells down its conc gradient brining glucose against its conc gradient via a cotransporter protein
glucose moves down its conc gradient into blood VIA FD

Question 21

absorption of lipids with roles of micelles

Answer 21

micelles contain bile salts monoglycerides and fatty acids
making monoglycerides and fatty acids more soluble in water and releasing monoglycerides and fatty acids into the lining of the ileum maintaining a high cinctrstion gradient of fatty acids to the cell
monoglycerides and fatty acids absorbed into epithelial cells by diffusion
triglycerides reformed and agreggate into globules

Question 22

BLOOD VESSELS
vena cava

Answer 22

carry deoxygenated blood from respiring body tissues to heart

Question 23

blood vessel
pulmonary artery

Answer 23

deoxygenated blood from heart to lungs

Question 24

blood vessels
pulmonary vein

Answer 24

carry oxygenated blood from lungs to heart

Question 25

blood vessel
aorta

Answer 25

carry oxygenated blood from heart to respiring tissues

Question 26

aterial systole

Answer 26

atria contract
increase pressure decrease in volume
when pressure in A>V AV valves open but SLV remain shut
blood pushed into ventricles

Question 27

ventricular systole

Answer 27

ventricles contract volume decreases pressure increases
AV valve close
SLV OPEN

blood pushed out of heart through arteries

Question 28

diastole

Answer 28

atria and ventricles relax
so volume increase and pressure decreases
SLV remain shut when pressure in A>V
AV OPEN
blood fills arteries via veins and flows passviely to ventricles

Question 29

arteries structure to function

Answer 29

thick muscle tissue can contact and control blood flow
thick elastic tissue than can recoil and stretch
thick walls to withstand pressure
narrow lumen to maintain pressure

Question 30

arterioles structure to function

Answer 30

thicker muscle walls than arteries contract and relax to control blood flow to capillaries
thin elastic layer as pressure surges are low

Question 31

veins structure to function.

Answer 31

wide lumen for less resistance to blood flow
little muscle and elastic as blood pressure is low
valves to prevent back flow of blood

Question 32

capillaries

Answer 32

thin layer of endothelial cells to decrease diffusion distance
;are network of capillaries to increase ether surface area fro diffusion
pores in side walls to allow larger substances through

Question 33

forming tissue fluid

Answer 33

high hydrostatic pressure in capillaries than tissue forcing fluid out out of capillaries but large plasma protiens remain

Question 34

return of tissue fluid to circulatory system

Answer 34

hydrostatic pressure reduces as fluid leaves capillary
increasing conc of plasma protiens due to water ,loos reaching water potential in capallires below tissue fluid
water enters capil from tissue fluid down a water potential gradient
excess water taken by lymph system and turned to circulatory system via veins

Question 35

causes of excess tissue fluid accumulation

Answer 35

low concentration of protein in blood plasma or salt conc is too high
eater potential in capillary not as low so water potential gradient is reduced
so more tissue fluid formed at arteriole end
high hydrostatic pressure less water absorbed at venule end by osmosis
Lymph system may not be able to drain excess fast enough

Question 36

xylem tissue function

Answer 36

transport water up stem to plant up leaves

Question 37

xylem tissue structure to function

Answer 37

cells joined with no end walls forming a long continuous tube so water can flow as a continuous column
cells have no nucleus and cytoplasm so easier flow of water
thick cell walls with lignin provide support and withstand tension
pits in side walls allowing lateral movement of water

Question 38

cohesion tension theory In the leaf

Answer 38

Water lost from leaf by transpiration water evaporates from mesophyll
cells into air spaces and water vapour diffuses through stomata
2. Reducing water potential of mesophyll cells
3. So water drawn out of xylem down a water potential gradient

Question 39

cohesion tension in xylem

Answer 39

creates tension
cohesion between water molecules bc of hydrogen bonds
water pulled as continuous column and water adheres to wall of xylem

Question 40

mass flow hypothesis
translocation of plants

Answer 40

At source, sucrose is actively transported into phloem sieve tubes By companion cells This lowers water potential in sieve tubes so water enters by osmosis
4. This increases hydrostatic pressure in sieve tubes (at source) creates a hydrostatic pressure gradient
5. So mass flow occurs - movement from source to sink
6. At sink, sucrose is removed by active transport to be used by respiring cells or stored in storage organs