exam questions

Question 1

describe structure of DNA keywords:

Answer 1

• polymer of nucleotides
• formed from deoxyribose, phosphate, organic base
• double helix
• types of bonds
• base pairing

Question 2

separation of DNA strands keywords:

Answer 2

• DNA helicacase
• breaks hydrogen bonds between base pairs

Question 3

role of DNA polymerase:

Answer 3

• joins adjacent nucleotides
• catalyses condensation + formation of phosphodiester bonds
  Yeah

Question 4

Suggest and explain why the combined actions of endopeptidases are more efficient than exopeptidases on their own (2 marks)

Answer 4

• Endopeptidases hydrolyse internal (peptide bonds) OR exopeptidases remove amino acids/hydrolyse (bonds at ends)
• more ends or increase in su4ace area for exopeptidases

Question 5

The addition of a respiratory inhibitor stoped the absorption of amino acids. Explain why (3 marks)

Answer 5

• no/less ATP produced OR no active transport
• sodium (ions) not moved (in/out of cell)
• no diffusion gradient for sodium to move into cell with amino acid OR no conc gradient for sodium (to move into cell with amino acid.)

Question 6

Suggest appropriate units the student should use to compare the distribution of stomata on leaves (1 mark)

Answer 6

Stomata per mm^2 or number per mm^2 or cm^2