topic 3 exchange/digestion/plant transport

Question 1

Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake{2}

Answer 1

. Larger organisms have a smaller surface area:volume
. so faster diffusion

Question 2

Explain why oxygen uptake is a measure of metabolic rate in organisms {1}

Answer 2

. cos oxygen used in respiration which produce atp

Question 3

Describe and explain 1 feature of alveolar epithelium that makes epithelium adapted as surface for gas exchange{2}

Answer 3

. Single layer of cells
. reduces diff pathway

Question 4

Suggest & explain how reduced tidal volume affects exchange of
CO2 between the blood and the alveoli {3}

Answer 4

. less CO2 exhaled/moves out of lung

2. so reduced diffusion/concentration gradient (between blood and
   alveoli)
3. Less movement of CO2 out of blood
   More carbon dioxide stays in blood;

Question 5

Describe & explain the mechanism that causes lungs to fill with air.

Answer 5

. diaphragm contracts AND external intercostal muscles contract
Ignore ribs move up and out
. lung volume increase,pressure decrease
. air moves down pressure gradient /enters from higher atmospheric pressure

Question 6

Describe and explain the advantage of the counter-current principle in gas exchange across a fish gill {3}

Answer 6

. water & blood flow in opp direction
. maintains conc gradient of oxygen
. diffusion along length of lamellae

Question 7

Use your knowledge of gas exchange in leaves to explain why plants
grown in soil w little water grow slowly {2}

Answer 7

. stomata close
. less CO2 uptake for less photosynthesis

Question 8

Describe the pathway taken by oxygen molecule from alveolus to blood {2}

Answer 8

. across alveolar epithelium
. epithelium of capillary

Question 9

Explain 3 ways an insect’s tracheal system is adapted for gas exchange {3}

Answer 9

. tracheoles have thin walls so short diffusion distance to cells;

. large number of tracheoles so short diffusion distance

. large number of tracheoles so large surface area for gas exchange

. lactate in the end of the tracheoles that moves out (into tissues)
during exercise so faster diffusion through the air to the gas
exchange surface;

. Body can be moved (by muscles) to move air so maintains conc gradient for O2

Question 10

The movement of Na+ out of the cell allows the absorption of glucose into
the cell lining the ileum.

Explain how {2}

Answer 10

. maintains conc gradient
for Na+ (from ileum into cell);

. Na+ moving in by co-transport, brings glucose with it;

Question 11

Describe the role of micelles in the absorption of fats into the cells lining
the ileum {3}

Answer 11

.micelles include bile salts and fatty acids;

. Make the fatty acids soluble in water

. carry fatty acids to cell/lining ileum

. maintain higher conc of fatty acids to cell/lining ileum
. fatty acids absorbed by diffusion

Question 12

suggest how the golgi apparatus is involved in the absorption of lipids {3}

Answer 12

. modifies triglycerides
. combines triglycerides with proteins
. forms vesicles

Question 13

Explain how water from tissue fluid is returned to the circulatory system{4}

Answer 13

. Plasma (proteins) remain
. reduces water potential of blood
. Water moves to blood by osmosis;
. Returns to blood by lymphatic system;

Question 14

Explain how an arteriole can reduce the blood flow into capillaries {2}

Answer 14

. muscle contracts
. constricts narrows arteriole

Question 15

what is tblood vessel carrying blood at lowest blood pressure {1}

Answer 15

. vena cava

Question 16

Describe the advantage of the Bohr effect during intense exercise {2}

Answer 16

. increases dissociation of oxygen;

. for aerobic respiration at the tissues/muscles/cells

Question 17

suggest & explain 1 way sieve tube cells are adapted for mass transport {2}

Answer 17

. thick walls
. resist pressures

Question 18

suggest & explain 1 way companion cells are adapted for transport of sugars between cells {2}

Answer 18

. they contain ATP
. to allow active transport of sugars

Question 19

Phloem pressure is reduced during the hottest part of the day. Explain why {3}

Answer 19

. high rate of evaporation
. cos more stomata open
.less water movement from xylem to phloem