PLANTS MASS TRANSPORT MARK
SCHEME ANSWERS
- Correct Answer Curve to right so Lowe affinity
Hemoglobin unloads more readily
more oxygen to cells
for faster respiration
High blood pressure leads to an accumulation of tissue fluid. Explain how - Correct
Answer 2. Increases outward pressure from (arterial) end of capillary / reduces inward
pressure at (venue) end of capillary;
3. (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Allow lymph system not able to drain tissues fast enough
High blood pressure = high hydrostatic pressure;
A student determined their pulse rate when sitting down. Describe how they could have
investigated whether their results were typical of all students of their age. - Correct
Answer Obtain pulse rates for a large number of students.
Belonging to a range of different sees.
Calculate the mean and standard deviation.
See if their mean lies within SD.
In a healthy person, blood moves in one direction as it passes through the heart. Give
two ways in which this is achieved. - Correct Answer Pressure gradient / moves from
high to low pressure;
2. Valves stop backflow;
Some people produce a much higher ventricular blood pressure than normal. This can
cause tissue fluid to build up outside the blood capillaries of these people. - Correct
Answer More fluid forced/filtered out of capillary/blood (due to high pressure);
Less return of fluid (into capillary/blood) due to pressure
(d) Some drugs used to reduce high ventricular blood pressure cause widening of blood
vessels.
Suggest how widening of blood vessels can reduce ventricular blood pressure. -
Correct Answer Larger lumen/volume (of blood vessels);
Reduces (blood) pressure (in blood vessels);
(d) The scientists calculated the cardiac output of the volunteers before and after the
exercise programmer. In some volunteers, their cardiac output stayed the same, even
though their resting heart rate decreased.
, Explain how their cardiac output could stay the same even when their resting heart rate
had decreased. - Correct Answer 2
2
2 max
(d) 1.
Cardiac output = stroke volume × heart rate
1. Accept CO = SV × HR
Allows comparison;
2. (So) stroke volume increases / increased size or volume of ventricles
The rise and fall in blood pressure in the aorta is greater than in the small arteries.
Suggest why. - Correct Answer (c) (Aorta)
1. (is) close / directly linked to the heart / ventricle / pressure is higher / is very
high;
2. (Aorta has) elastic tissue;
Accept elasticity
Ignore reference to muscle
3. (Aorta has) stretch / recoil.
(a) Use information from the figure to explain how the pressure in the dog's ventricle is
related to blood flow into the aorta. - Correct Answer
(e) The student then compared the rate of transpiration (evaporation of water) from the
two species of plant. She did this by measuring the rate of water uptake by each plant
species.
Suggest two reasons why the rate of water uptake by a plant might not be the same as
the rate of transpiration. - Correct Answer Water used for support/turgidity;
2. Water used in photosynthesis;
Using the diagram, suggest and explain one other way in which sieve cells are
adapted for mass transport - Correct Answer No / few organelles / very little
cytoplasm / cytoplasm at edge / more room /
2. (So) easier / more flow / (thick / strong walls) resist pressure.
(d) The plants grown at higher temperatures had a lower number of stomata per mm2.
This would be an advantage to the plant because the transpiration rate increases as the
temperature increases.
Explain why the transpiration rate increases when the temperature increases. - Correct
Answer 1. Molecules have more kinetic energy;
Accept KE
2. Faster diffusion of water / more evaporation of water (as temperature increases in
leaf);
For this point, diffusion must relate to movement of water
3. For this point, diffusion must relate to movement of water
SCHEME ANSWERS
- Correct Answer Curve to right so Lowe affinity
Hemoglobin unloads more readily
more oxygen to cells
for faster respiration
High blood pressure leads to an accumulation of tissue fluid. Explain how - Correct
Answer 2. Increases outward pressure from (arterial) end of capillary / reduces inward
pressure at (venue) end of capillary;
3. (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Allow lymph system not able to drain tissues fast enough
High blood pressure = high hydrostatic pressure;
A student determined their pulse rate when sitting down. Describe how they could have
investigated whether their results were typical of all students of their age. - Correct
Answer Obtain pulse rates for a large number of students.
Belonging to a range of different sees.
Calculate the mean and standard deviation.
See if their mean lies within SD.
In a healthy person, blood moves in one direction as it passes through the heart. Give
two ways in which this is achieved. - Correct Answer Pressure gradient / moves from
high to low pressure;
2. Valves stop backflow;
Some people produce a much higher ventricular blood pressure than normal. This can
cause tissue fluid to build up outside the blood capillaries of these people. - Correct
Answer More fluid forced/filtered out of capillary/blood (due to high pressure);
Less return of fluid (into capillary/blood) due to pressure
(d) Some drugs used to reduce high ventricular blood pressure cause widening of blood
vessels.
Suggest how widening of blood vessels can reduce ventricular blood pressure. -
Correct Answer Larger lumen/volume (of blood vessels);
Reduces (blood) pressure (in blood vessels);
(d) The scientists calculated the cardiac output of the volunteers before and after the
exercise programmer. In some volunteers, their cardiac output stayed the same, even
though their resting heart rate decreased.
, Explain how their cardiac output could stay the same even when their resting heart rate
had decreased. - Correct Answer 2
2
2 max
(d) 1.
Cardiac output = stroke volume × heart rate
1. Accept CO = SV × HR
Allows comparison;
2. (So) stroke volume increases / increased size or volume of ventricles
The rise and fall in blood pressure in the aorta is greater than in the small arteries.
Suggest why. - Correct Answer (c) (Aorta)
1. (is) close / directly linked to the heart / ventricle / pressure is higher / is very
high;
2. (Aorta has) elastic tissue;
Accept elasticity
Ignore reference to muscle
3. (Aorta has) stretch / recoil.
(a) Use information from the figure to explain how the pressure in the dog's ventricle is
related to blood flow into the aorta. - Correct Answer
(e) The student then compared the rate of transpiration (evaporation of water) from the
two species of plant. She did this by measuring the rate of water uptake by each plant
species.
Suggest two reasons why the rate of water uptake by a plant might not be the same as
the rate of transpiration. - Correct Answer Water used for support/turgidity;
2. Water used in photosynthesis;
Using the diagram, suggest and explain one other way in which sieve cells are
adapted for mass transport - Correct Answer No / few organelles / very little
cytoplasm / cytoplasm at edge / more room /
2. (So) easier / more flow / (thick / strong walls) resist pressure.
(d) The plants grown at higher temperatures had a lower number of stomata per mm2.
This would be an advantage to the plant because the transpiration rate increases as the
temperature increases.
Explain why the transpiration rate increases when the temperature increases. - Correct
Answer 1. Molecules have more kinetic energy;
Accept KE
2. Faster diffusion of water / more evaporation of water (as temperature increases in
leaf);
For this point, diffusion must relate to movement of water
3. For this point, diffusion must relate to movement of water
