Topic 3 - Summary flashcards

Question 1

What is Fick’s Law?

Answer 1

Diffusion is proportional to (SA x Diff Grad) / thickness of the diffusion pathway

Question 2

Insect - structural adaptations

Answer 2

1) Tracheoles have thin walls so short diffusion distance to cells;
2) Highly branched / large number of tracheoles so short diffusion distance to cells;
3) Highly branched / large number of tracheoles so large surface area (for gas exchange);
4) Tracheae provide tubes full of air so fast diffusion (into insect tissues);
5) Fluid in the end of the tracheoles that moves out (into tissues) during exercise so faster diffusion through the air to the gas exchange surface;
6) Body can be moved (by muscles) to move air so maintains diffusion / concentration gradient for oxygen / carbon dioxide

Question 3

Fish - structural adaptation

Answer 3

1) Many lamellae / filaments so large surface area

2) Thin (surface) so short diffusion pathway

Question 4

Fish - Countercurrent mechanism

Answer 4

1) Water and blood flow in opposite directions
2) Blood always passing water with a higher oxygen concentration
3) Diffusion gradient maintained throughout length (of gill)

Question 5

Gas exchange system

Answer 5

1) Trachea, bronchi, bronchioles, alveoli
2) Breathing in - external intercostal muscles contract pulling ribs up and out. Diaphragm contracts and flattens.
3) Causes volume increase and pressure decrease in thoracic cavity (to below atmospheric, resulting in air moving in)
4) Breathing out - Diaphragm relaxes back to its dome shape and internal intercostal muscles contract pulling the ribs down and in.
5) Causes volume decrease and pressure increase in thoracic cavity (to above atmospheric, resulting in air moving out)

Question 6

Lung gas exchange adaptation

Answer 6

1) (The alveolar epithelium) is one cell thick

2) Creating a short diffusion pathway / reduces the diffusion distance

Question 7

Leaf adaptations for gas exchange

Answer 7

1) (Carbon dioxide enters) via stomata
2) (Stomata opened by) guard cells;
3) Diffuses through air spaces;
4) Down diffusion gradient

Question 8

Bohr shift

Answer 8

1) Increases/more oxygen dissocitation/unloading

2) By decreasing blood pH/increasing activity

Question 9

Oxygen dissociation (shift to left)

Answer 9

1) Lower affinity for O2 at low partial pressures;

2) Easier unloading of O2 for (aerobic respiration)

Question 10

Oxygen dissociation - high metabolism organism

Answer 10

1) Curve to the right so lower affinity / % saturation (of haemoglobin)
2) Haemoglobin unloads / dissociates more readily
3) More oxygen to cells / tissues / muscles;
4) For greater / more / faster respiration

Question 11

What is digestion?

Answer 11

Hydrolysis of large insoluble substances to smaller soluble substances

Question 12

Starch digestion

Answer 12

Salivary amylase breaks down starch into maltose

Question 13

Protein digestion

Answer 13

1) Hydrolysis of peptide bonds
2) Endopeptidases act in the middle of protein
3) Exopeptidases act at the end of protein
4) Dipeptidase acts on dipeptide/between two amino acids

Question 14

Lipid digestion - bile salts

Answer 14

1) Small droplets have a larger surface area to volume ratio

2) More surface for lipase (to act), leading to faster digestion of trigylcerides

Question 15

Lipid absorption

Answer 15

1) Micelles contain bile salts and fatty acids/monoglycerides
2) Make fatty acids/monoglycerides more soluble in water
3) Fatty acids/monoglycerides absorbed by diffusion
4) Triglycerides reformed in cells
5) Vesicles move to cell membrane
6) Golgi modifies / processes triglycerides
7) Combines triglycerides
8) Packaged for release / exocytosis

Question 16

Artery and arteriole structure

Answer 16

Elastic tissue:
1) Elastic tissue stretches under pressure / when heart beats then recoils / springs back
2) Evens out pressure / flow
Muscle:
3) Muscle contracts to reduce diameter of lumen / vasoconstriction / constricts vessel
4) Changes flow / pressure
Epithelium:
5) Epithelium smooth
6) Reduces friction / blood clots / less resistance

Question 17

Aorta structure to function:

Answer 17

1) Elastic tissue to allow stretching / recoil / smoothes out flow of blood / maintains pressure
2) (Elastic tissue) stretches when ventricles contract
3) Muscle for contraction /vasoconstriction
4) Thick wall withstands pressure
5) Smooth endothelium reduces friction
6) Aortic value / semi-lunar valve prevents backflow

Question 18

Tissue fluid formation and high blood pressure

Answer 18

1) High blood pressure = high hydrostatic pressure
2) Increases outward pressure from (arterial) end of capillary /reduces inward pressure at venule end of capillary
3) So more tissue fluid is formed / less tissue fluid is reabsorbed

Question 19

Dissection safety

Answer 19

Use a sharp scalpel/scissors
Wash hands/wear gloves
Disinfect bench/equipment
Cover any cuts
Cut away from self/others/on a hard surface
Safe disposal

Question 20

Transpiration

Answer 20

1) Stomata open and photosynthesis increases / transpiration increases
2) More water pulled up due to cohesion between water molecules / by cohesion tension
3) Water pulling up trunk / moves up at fast rate under tension
4) Sticking / adhesion (between water and) cells / walls / pulls xylem in

Question 21

Factors affecting rate of transpiration

Answer 21

Light
Humidity
Air movement
Temperature

Question 22

Xerophyte adaptations

Answer 22

1) Hairs to ‘trap’ water vapour and water potential gradient decreased
2) Stomata in pits/grooves so ‘trap’ water vapour and water potential gradient decreased
3) Thick (cuticle/waxy) layer so increases diffusion distance
4) Waxy layer/cuticle so reduces evaporation/transpiration
5) Curled leaves so ‘trap’ water vapour and water potential gradient decreased
6) Spines/needles so reduces surface area to volume ratio

Question 23

Translocation

Answer 23

1) (At source) sucrose is actively (transported) into the phloem/sieve element/tube
2) By companion/transfer cells
3) Lowers water potential in phloem/sieve element/tube and water enters by osmosis
4) Produces high hydrostatic pressure
5) Mass flow / transport towards sink/roots/storage tissues
6) At sink/roots sugars are removed/unloaded

Question 24

Haemoglobin structure and binding

Answer 24

1) Binding of first oxygen changes tertiary structure of haemoglobin
2) Creates another binding site