2016 AS Paper 2

Question 1

Where do exo, endo and dipeptidases work?

Answer 1

Endopeptidase - Hydrolyse internal peptide bonds

Exopeptidase - Hydrolyse peptide bonds at ends

Dipeptidases - Hydrolyse peptide bonds

Question 2

What effect does respiratory inhibitors have in cotransport?

Answer 2

Less ATP produced

Sodium ions cannot be moved out of the cell

No diffusion gradient for sodium

Question 3

Why are thin tissues good to examine?

Answer 3

Produces single layer of cells

Allows light to pass through

Question 4

What are the xerophytic plant features?

Answer 4

Hairs - Water vapour trapped and water potential gradient decreased

Thick waxy layer - Increased diffusion distance

Waxy layer - Reduced evaporation/transpiration

Needles - Reduced SA:Vol ratio

Question 5

What is the purpose of phosphate?

Answer 5

Required to make RNA

Required to make DNA

Required to make ATP

Required to make membranes

Required for phosphorylation

Question 6

How can smoking affect breathing?

Answer 6

Internal intercostal muscles less effective

Breathing rate is reduced

Less oxygen uptake