mass transprot

Question 1

Explain how water from tissue fluid is returned to the circulatory system.

Answer 1

1. (Plasma) proteins remain;
   2.Reduces water potential (of blood);
2. Water moves (to blood) by osmosis;
3. Returns (to blood) by lymphatic system;

Question 2

Describe two precautions the student should take when clearing away after
the dissection.

Answer 2

dispose in a separate bag
disinfect surfaces

Question 3

Explain how an arteriole can reduce the blood flow into capillaries.

Answer 3

1. Muscle contracts;
2. Constricts/narrows arteriole/lumen;

Question 4

Tick (✓) one box next to the blood vessel carrying blood at the lowest
blood pressure.

Capillary

Pulmonary vein

Renal vein

Vena cava

Answer 4

vena cava

Question 5

Describe and explain the effect of increasing carbon dioxide concentration
on the dissociation of oxyhaemoglobin.

Answer 5

lowers pH
Chang tertiary structure lowering affinity so more unloading

Question 6

explain how the seal’s myoglobin
dissociation curve shows the seal is adapted for diving.

Answer 6

High(er) affinity for O2
Allows (aerobic) respiration when diving/at low(er) pO2

Question 7

how does the heart maintains a unidirectional flow of blood.

Answer 7

Pressure in (left) atrium is higher than in ventricle/B causing valve to open;
Pressure in (left) ventricle/B is higher than in atrium causing valve to close;

Question 8

Binding of one molecule of oxygen to haemoglobin makes it easier for a
second oxygen molecule to bind.

Answer 8

Binding of first oxygen changes tertiary / quaternary (structure) of haemoglobin;
Creates / leads to / uncovers second / another binding site

Question 9

Explain the role of the heart in the formation of tissue fluid.

Answer 9

1. Contraction of ventricle(s) produces high blood / hydrostatic pressure;
2. (This) forces water (and some dissolved
   substances) out (of blood capillaries);

Question 10

Phloem pressure is reduced during the hottest part of the day why

Answer 10

more evaporation of water from transpiration
so more water lost through stomata
less water moves In from the xylem to the phloem

Question 11

Give two other measurements he made to calculate the rate of water
movement

Answer 11

Initial and final mass
Number of (groups of) xylem vessels;

Question 12

how does water move up the plant

Answer 12

Water evaporates/is transpired and lost from stomata
causes a water potential gradient
hydrogen bonds form cohesions so water is pulled up

Question 13

The student used a sharp scalpel to cut the celery. Describe how she
should ensure she handled the scalpel safely during this procedure.

Answer 13

1. Cut away from body;
2. Against hard/non-slip/flat surface;

Question 14

is there are outliers what should you use?

Answer 14

teh median

Question 15

Describe the cohesion-tension theory of water transport in the xylem.

Answer 15

1. Water lost from leaf because of transpiration through STOMATA
2. so there is a water potential gradient
3. 3. Water pulled up xylem
4. Water molecules cohere / ‘stick’ together by hydrogen bonds;
5. (forming continuous) water column;

Question 16

The rate of water movement through a shoot in a potometer may not be the
same as the rate of water movement through the shoot of a whole plant.

Answer 16

plant has roots

Question 17

how does translocation work.

Answer 17

1. In source / leaf sugars actively transported into phloem;
2. By companion cells;
3. Lowers water potential of sieve cell / tube and water enters by
   osmosis;
4. Increase in pressure causes mass movement (towards sink /
   root);
5. Sugars used / converted in root for respiration for storage.