MASS TRANSPORT IN ANIMALS Flashcards
Q1.Scientists investigated the effect of a 6-week exercise programme on the resting heart rate
of males and females.
The scientists recruited a large group of male volunteers and a large group of female
volunteers. They measured the resting heart rate of each volunteer before the exercise
programme. Both groups took part in the same exercise programme. The scientists
measured the resting heart rate of each volunteer after the exercise programme.
The scientists determined the mean resting heart rate and the range of resting heart rates
for each group before and after the exercise programme. The graph shows their results.
(c) The scientists used the percentage change in the mean resting heart rate after the
exercise programme to compare the results for males and females.
Explain why they used percentage change in the resting heart rate (2)
- Allows comparison;
2. (Initial / resting) heart rates different (between males and females).
(d) The scientists calculated the cardiac output of the volunteers before and after the
exercise programme. 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. (2)
- Cardiac output = stroke volume × heart rate
- Accept CO = SV × HR
- (So) stroke volume increases / increased size or volume of ventricles.
- Neutral: more blood leaves heart
- If the term stroke volume is not used, it must be defined
Q2.(a) What is the function of the coronary arteries?
- (Carry) oxygen / glucose;
Accept: oxygenated blood
Ignore references to removing waste products
Ignore references to arteries ‘pumping’ blood - (To) heart muscle / tissue / cells / myocytes.
Must be supply to heart or cardiac
(i) Which of the blood vessels A to H is the vena cava
?
(ii) Which of the blood vessels A to H is the renal artery
A
H
(c) Figure 2 shows how the blood pressure changes as blood travels from the aorta to
the capillaries.
The rise and fall in blood pressure in the aorta is greater than in the small
arteries.Suggest why. (3)
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. Q Reject: contracts / relaxes / pumps Accept: for mp 2 and mp 3, converse for small arteries if qualified by little / less
Q3.The mean internal diameter and the mean speed of blood flow for different human blood
vessels are shown below in the table.
(a) Although the speed of blood flow in an arteriole is greater than speed of blood flow
in a capillary, blood does not accumulate in the arterioles.
Explain why. (1)
- Many / more capillaries (than arterioles);
- (Cross-sectional) area of capillaries (much) greater (than of arterioles).
Note: maximum of 1 mark for this question
(b) Other than causing slow blood flow, explain one advantage of capillaries being
narrow. (2)
- Short pathway / short distance between blood and outside of capillary;
Reference to blood and cells required - Large surface area (of blood) in contact with walls of capillaries;
Idea is per unit volume of blood but candidates need not say
this - Fast exchange / fast diffusion / fast osmosis.
Must relate to increased speed
(c) What factor limits the minimum internal diameter of the lumen of a capillary?
(1)
Width / size / diameter of blood cell. Accept named blood cell Reject platelet Accept idea that below a certain diameter friction becomes too great for blood to flow
d) The volume of blood leaving the capillary network into the veins is less than the
volume of blood entering from the arteries.
Explain why. (1)
(d) (Fluid) in tissue fluid / (fluid) in lymph.
Q4.A principle of homeostasis is the maintenance of a constant internal environment. An
increase in the concentration of carbon dioxide would change the internal environment
and blood pH.
Explain the importance of maintaining a constant blood pH. (3)
- Named protein / enzyme (in blood) sensitive to / affected by change in
pH;
Accept converse for MP2 and MP3.
Named example should be a protein that might be affected
(by change in pH) eg haemoglobin, carrier protein in plasma
membrane.
Accept ‘change in H+
concentration’ for ‘change in pH’. - (Resultant) change of charge / shape / tertiary structure;
The change in charge idea relates to the enzyme / protein
and not the blood (plasma) or red blood cells.
‘Denaturation’ alone is insufficient. - Described effect on named protein or enzyme.
e.g. less oxygen binds with haemoglobin / less transport across membranes /
fewer substrates can fit active site / fewer enzyme-substrate complexes.
Idea of ‘less’ or ‘fewer’ required. Ignore suggestion of ‘no’ or
‘none’.
Q5.The figure below represents a capillary surrounded by tissue fluid.
The values of the hydrostatic pressure are shown.
(a) Use the information in the figure above to explain how tissue fluid is formed.
(2)
- (Overall) outward pressure of 3.2 kPa;
2. Forces small molecules out of capillary.
(b) The hydrostatic pressure falls from the arteriole end of the capillary to the venule
end of the capillary. Explain why. (1)
(b) Loss of water / loss of fluid / friction (against capillary lining).
(c) High blood pressure leads to an accumulation of tissue fluid. Explain how.
(3)
- High blood pressure = high hydrostatic pressure;
- Increases outward pressure from (arterial) end of capillary / reduces
inward pressure at (venule) end of capillary; - (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Allow lymph system not able to drain tissues fast enough
(d) The water potential of the blood plasma is more negative at the venule end of the
capillary than at the arteriole end of the capillary. Explain why. (3)
- Water has left the capillary;
- Proteins (in blood) too large to leave capillary;
- Increasing / giving higher concentration of blood proteins (and thus wp).
0 1 . 2 Name the blood vessels that carry blood to the heart muscle.
(1)
Coronary arteries;
