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

Tidal volume is reduced

Less oxygen uptake

Question 7

How can a mutation in protein production process impact the function of a protein.

Answer 7

Change in DNA base sequence

Change in amino acid sequence

Alters position of hydrogen/ionic/disulfide bonds

Change in tertiary structure

Question 8

How can an increase in ventricular pressure affect tissue fluid

Answer 8

More fluid forced out of capillary

Less return of fluid due to pressure

Question 9

How is starch structure related to its function?

Answer 9

Helical shape - Compact

Large molecule - Cannot cross cell surface membrane

Branched - Glucose released for respiration

Insoluble - Will not leave cell membrane by osmosis

Question 10

How is cellulose structure linked to its function?

Answer 10

Long straight chains of Beta-Glucose

Joined by hydrogen bonds

Forms microfibrils

Provides strength to cell wall

Question 11

Describe the processes involved in transport of sugars in plant cells?

Answer 11

At source sucrose is actively transported into the phloem

By companion cells

Lowers water potential in phloem and water enters by osmosis

Produces high hydrostatic pressure

Mass flow towards sink

At sink sugars are removed