Random Past Paper Questions

Question 1

Describe the induced fit model of enzyme action and how an enzyme acts as a catalyst (3)

Answer 1

1. Substrate binds to the active site
2. Active site changed shape so its complimentary to substrate
3. Which reduces activation energy

Question 2

Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake. (2)

Answer 2

1. Larger organisms have a smaller surface area: volume ratio
2. So faster diffusion / short diffusion pathway

Question 3

Explain how the counter-current principle allows efficient oxygen uptake in the
fish gas exchange system. (2)

Answer 3

1. Blood and water flow in opposite directions
2. Diffusion/concentration gradient (maintained) along (length of) lamella/filament;

Question 4

Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation

Answer 4

1. tRNA brings specific amino acid (to ribosome);
2. Anticodon (on tRNA) binds to codon (on mRNA);
3. Amino acids join by condensation reaction (using ATP)
   OR
   Amino acids join to form a peptide bond (using ATP);