2010 Jun Unit 4

Question 1

Nitrogen is reduced

Answer 1

NH4+, NH3

Question 2

What does the Hardy–Weinberg principle predict?

Answer 2

The frequency/proportion of alleles (of a particular gene)
No genetic change over time
Providing no mutation

Question 3

What is the evidence from the table that non-agouti and blotched are alleles of different genes?

Answer 3

Frequencies (of these alleles) add up to more

than 1;

Question 4

Describe and explain how intensive rearing of domestic livestock would affect, The absorbed from the gut

Answer 4

Increase because fed concentrates

Question 5

Describe and explain how intensive rearing of domestic livestock would affect. Respiration

Answer 5

Decrease because movement restricted

Question 6

The pioneer plants had seeds that germinate better when the temperature fluctuates.
Explain the advantage of this to these pioneer plants.

Answer 6

Bare soil temperatures fluctuate;

More bare soil, early/at start of succession/when few plants

Question 7

Describe the part played by the inner membrane of a mitochondrion in producing ATP.

Answer 7

Electrons transferred down electron transport chain
Provide energy to take H+ into space between membranes
Protons/H+ pass back, through membrane/into matrix/through ATPase;
Energy to produce ATP

Question 8

Explain why the scientist did not use glucose as the respiratory substrate

Answer 8

Glucose is used/broken down during glycolysis
Breakdown of glucose/glycolysis in the cytoplasm/not in
mitochondria
Glucose cannot cross mitochondrial membrane/does not enter mitochondria

Question 9

Use the words probability and chance to explain the meaning of differed significantly
(p < 0.05)

Answer 9

There was a probability of less than 0.05

That the difference was due to chance

Question 10

The ratio of the dry biomass of animals to the dry biomass of seaweeds is always a lot
less than one. Explain why.

Answer 10

Plants are producers
Loss of energy between trophic levels
As a result of respiration

Question 11

The concentrations of carbon dioxide in the air at different heights above the ground in forest changes over a period of 24 hours. Use your knowledge of photosynthesis to
describe these changes and explain why they occur.

Answer 11

High concentration of carbon dioxide linked with
night
No photosynthesis in dark
(In dark) plants (and other organisms) respire
rate of
photosynthesis greater than rate of respiration
Decrease in carbon dioxide concentration with height
At ground level fewer leaves/less photosynthesising

Question 12

n the light-independent reaction of photosynthesis, the carbon in carbon dioxide
becomes carbon in triose phosphate. Describe how

Answer 12

Carbon dioxide combines with ribulose bisphosphate
To produce two molecules of glycerate 3-phosphate
Reduced to triose phosphate
Requires reduced NADP
Energy from ATP