AQA A-Level Biology Paper 1 2021
questions well solved latest update
2025.
1.1 Describe the induced fit model of enzyme action and how an
enzyme acts as a catalyst. - Answer - The substrate binds to the active
site and forms an ES complex.
- The active site changes shape slightly so it's complimentary to the
substrate.
- This reduces the activation energy.
1.2 Tick one box to show which are the substrate the scientists must
add to the reaction mixture is to produce ATP. - Answer - Adenosine
diphosphate.
1.3 Suggest and explain a procedure the scientist could have used to
stop each reaction. - Answer - The nature of the enzyme by putting it in
ice.
1.4 Explain the change in ATP concentration with increasing inorganic
phosphate concentration - Answer - With increasing phosphate
concentration more ES complex is form.
, AQA A-Level Biology Paper 1 2021
questions well solved latest update
2025.
- And at 40 mol dm3, all active sites are occupied.
2.1 Explain the advantage for large animals of having a specialised
system that facilitates oxygen uptake. - Answer - Large organisms have
a smaller surface area to volume ratio.
- This means they overcome a long diffusion pathway.
2.2 Suggest how the environmental conditions have resulted in
adaptations of systems using model A rather than model B. - Answer -
Water is more dense than air.
- So it supports the gills.
2.3 A student studies figure 3 and concluded that the fish gas exchange
system is more efficient than the human gas exchange system. Use
figure 3 to justify this conclusion. - Answer - The difference of oxygen
concentration between the artery and vein is larger in the fish than the
human.
- So the fish remove a greater amount of oxygen that they intake.
questions well solved latest update
2025.
1.1 Describe the induced fit model of enzyme action and how an
enzyme acts as a catalyst. - Answer - The substrate binds to the active
site and forms an ES complex.
- The active site changes shape slightly so it's complimentary to the
substrate.
- This reduces the activation energy.
1.2 Tick one box to show which are the substrate the scientists must
add to the reaction mixture is to produce ATP. - Answer - Adenosine
diphosphate.
1.3 Suggest and explain a procedure the scientist could have used to
stop each reaction. - Answer - The nature of the enzyme by putting it in
ice.
1.4 Explain the change in ATP concentration with increasing inorganic
phosphate concentration - Answer - With increasing phosphate
concentration more ES complex is form.
, AQA A-Level Biology Paper 1 2021
questions well solved latest update
2025.
- And at 40 mol dm3, all active sites are occupied.
2.1 Explain the advantage for large animals of having a specialised
system that facilitates oxygen uptake. - Answer - Large organisms have
a smaller surface area to volume ratio.
- This means they overcome a long diffusion pathway.
2.2 Suggest how the environmental conditions have resulted in
adaptations of systems using model A rather than model B. - Answer -
Water is more dense than air.
- So it supports the gills.
2.3 A student studies figure 3 and concluded that the fish gas exchange
system is more efficient than the human gas exchange system. Use
figure 3 to justify this conclusion. - Answer - The difference of oxygen
concentration between the artery and vein is larger in the fish than the
human.
- So the fish remove a greater amount of oxygen that they intake.
