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2024 AQA A LEVEL BIOLOGY TOPIC 3 EXAM QUESTIONS WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY TOPIC 3 EXAM QUESTIONS WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY TOPIC3 EXAM QUESTIONS WITH
CORRECT ANSWERS
The hydrostatic pressure falls from the arteriole end of the capillary to the
venule end of the capillary. Explain why - CORRECT-ANSWERSLoss of water
High blood pressure leads to an accumulation of tissue fluid. Explain how [3]
- CORRECT-ANSWERSHigh blood pressure = high hydrostatic pressure;
Increase outward pressure from (arterial) end of capillary;
(So) more tissue fluid
Describe the advantage of the Bohr effect during intense exercise. [2] -
CORRECT-ANSWERS1. Increases dissociation of oxygen;
Accept unloading/ release/reduced affinity for dissociation 2. For aerobic
respiration at the tissues/muscles/cells
OR
Anaerobic respiration delayed at the tissues/muscles/cells
OR
Less lactate at the tissues/muscles/cells;
EPO is another performance-enhancing drug. It can increase the haematocrit
(the percentage of red blood cells in blood).
A heart attack is caused by a lack of glucose and oxygen being delivered to
cardiac muscle via the coronary arteries. The overuse of EPO can increase
the risk of a heart attack. Suggest how. [2] - CORRECT-ANSWERS1. (EPO)
causes blood to thicken;
Accept descriptions of thickening, eg more viscous
2. (The thickened blood) could block the coronary arteries OR
(The thickened blood) slows blood flow
OR
(The thicker blood) could cause clots;
Reject atheroma/plaque (forms)
Accept could cause thrombus/embolus
The normal haematocrit for human males is 47(±5)%. For professional male
cyclists, the maximum haematocrit allowed is 50%.
A student suggested that professional male cyclists should be allowed to use
EPO until their haematocrit is 50%.
, Give two reasons why this suggestion is not valid. [2] - CORRECT-ANSWERS1.
Some cyclists will gain a bigger advantage/increase
OR
Cyclists with a haematocrit of 50% would not be able to gain an advantage;
Accept use of the data, or suitable calculations, eg some may have an 8%
increase, others 0%
Some cyclists might naturally have a haematocrit over 50% (and so not be
allowed to compete)
2. There are health risks (associated with) taking EPO;
Describe and explain the effect of increasing carbon dioxide concentration
on the dissociation of oxyhaemoglobin. [2] - CORRECT-ANSWERS1.
Increases/more oxygen dissociation/unloading
OR
Deceases haemoglobin's affinity for O2;
Accept more readily
Accept releases more O2
2. (By) decreasing (blood) pH/increasing acidity;
Give two safety precautions that should be followed when dissecting a heart.
[1] - CORRECT-ANSWERSUse 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
Explain how valve A in Figure 1 maintains a unidirectional flow of blood. [2]
Valve A is the atrioventricular valve. - CORRECT-ANSWERS1. Pressure in (left)
atrium is higher than in ventricle/B causing valve to open;
OR
(When) pressure above valve is higher than below valve it opens;
Ignore pressure in front of/behind valve
As long as direction of opening/closing of valve is correct, ignore 'semi lunar'
2. Pressure in (left) ventricle/B is higher than in atrium causing valve to
close;
OR
(When) pressure in below valve is higher than above valve it closes;
Name the blood vessels that carry blood to the heart muscle. [1] - CORRECT-
ANSWERSCoronary arteries;
Binding of one molecule of oxygen to haemoglobin makes it easier for a
second oxygen molecule to bind. Explain why. [2] - CORRECT-ANSWERS1.
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