EXAM QUESTIONS

Question 1

Standard deviation…

Answer 1

Spread of data around the mean.
Different to the range.

Question 2

Outline the role of water in photosynthesis.

Answer 2

Water split by light in photolysis - non cyclic photophosphorylation as electron + H+ donor to restore electrons lost from PSII by photoionisation.
Chemiosmosis + ATP synthesis

Question 3

How many ATP molecules are required to make 1 hexose sugar in photosynthesis and explain.

Answer 3

18 as 6 turns of Calvin cycle needed and 3 ATP used every turn.

Question 4

Describe role of NADPH in photosynthesis.

Answer 4

Coenzyme in Calvin cycle and transfers H to ATP synthase from light dependent to light independent.

Question 5

Explain why there are always low levels of RuBP in stroma.

Answer 5

Calvin cycle constantly repeating, so when regenerated from TP, quickly reacted with CO2 to make more GP.

Question 6

Rubsico’s optimum pH is 8. Why can plants only produce triose phosphate in the light?

Answer 6

Light energy needed to power light dependent reactions to make NADPH + ATP. H+ pumped across membrane, increasing pH more alkaline. Light dependent stop, fewer H+ out stroma so builds up - away from optimum.
No light, not enough NADPH + ATP to reduce GP to TP.

Question 7

Suggest why a lack of iron in the soil may reduce growth rate in plants.

Answer 7

Iron needed for electron carrier proteins. Less light dependent reaction, so make less ATP + NADPH. Not enough TP.
Cellulose made from glucose - grow plant.

Question 8

Outline the hormonal ad nervous mechanisms involved in the control of heart rate.

Answer 8

Hormonal stimulation of individual muscle cells would result in uncoordinated response
Stimulation of SAN results in
coordinated action of the cardiac muscle
hormonal stimulation of individual muscle cells
will not result in a change in heart rate stimulation of SAN results in
a change in heart rate
hormone receptors only present on the SAN - not have receptors

Question 9

Explain why the incomplete breakdown of glucose in anaerobic respiration produces less ATP than aerobic respiration.
(5 MARKS)

Answer 9

1 - glycolysis occurs
2 - produces 2 molecules of ATP (net)
3 - only substrate level phosphorylation occurs
4 - oxygen not available as final electron acceptor
5 - pyruvate / ethanal used to regenerate NAD for glycolysis to continue ;
6 - Krebs cycle and electron transport chain / chemiosmosis /
oxidative phosphorylation ,do not occur (ONLY occurs in aerobic)