AQA AS BIOLOGY paper 2 Solutions
(100%Correct)
Endopeptidases and exopeptidases are involved in the hydrolysis of proteins. Name the
other type of enzyme required for the complete hydrolysis of proteins to amino acids. -
ANS-dipeptidases
Suggest and explain why the combined actions of endopeptidases and exopeptidases
are more efficient than exopeptidases on their own. - ANS-- endopeptidases hydrolyse
internal peptide bonds
- increase in surface area for exopeptidases
The addition of a respiratory inhibitor stops the absorption of amino acids. Explain why. -
ANS-- no ATP produced
- sodium ions aren't moved into and out of the cell
- no diffusion gradient for sodium to move into cell with amino acid
Suggest appropriate units the student should use to compare the distribution of stomata
on leaves. - ANS-stomata per mm^2
The pieces of leaf tissue examined were very thin. Explain why this was important. -
ANS-- single layer of cells
- so light can pass through
Give two reasons why it was important that the student counted the number of the
stomata in several parts of each piece of leaf tissue. - ANS-- distribution may not be
uniform
- to obtain a reliable mean
Other than the distribution of stomata, suggest and explain two xerophytic features the
leaves of this plant might have. - ANS-- curling of leaves to trap water vapour and water
potential gradient decreased
- thick waxy cuticle increases diffusion distance
Suggest two reasons why the rate of water uptake by a plant might not be the same as
the rate of transpiration. - ANS-- water is used in photosynthesis
(100%Correct)
Endopeptidases and exopeptidases are involved in the hydrolysis of proteins. Name the
other type of enzyme required for the complete hydrolysis of proteins to amino acids. -
ANS-dipeptidases
Suggest and explain why the combined actions of endopeptidases and exopeptidases
are more efficient than exopeptidases on their own. - ANS-- endopeptidases hydrolyse
internal peptide bonds
- increase in surface area for exopeptidases
The addition of a respiratory inhibitor stops the absorption of amino acids. Explain why. -
ANS-- no ATP produced
- sodium ions aren't moved into and out of the cell
- no diffusion gradient for sodium to move into cell with amino acid
Suggest appropriate units the student should use to compare the distribution of stomata
on leaves. - ANS-stomata per mm^2
The pieces of leaf tissue examined were very thin. Explain why this was important. -
ANS-- single layer of cells
- so light can pass through
Give two reasons why it was important that the student counted the number of the
stomata in several parts of each piece of leaf tissue. - ANS-- distribution may not be
uniform
- to obtain a reliable mean
Other than the distribution of stomata, suggest and explain two xerophytic features the
leaves of this plant might have. - ANS-- curling of leaves to trap water vapour and water
potential gradient decreased
- thick waxy cuticle increases diffusion distance
Suggest two reasons why the rate of water uptake by a plant might not be the same as
the rate of transpiration. - ANS-- water is used in photosynthesis
