2009 June Unit 2

Question 1

Blood vessel B contains smooth muscle in its walls. Explain how this muscle may reduce the blood flow to the small intestine.

Answer 1

Contracts

Causing vasoconstriction/narrow lumen

Question 2

Explain the diffidence in % of guanine bases

Answer 2

Diff proteins
Diff genes
Diff base sequence

Question 3

Why us bacterium A restaurant to penicillin

Answer 3

Horizontal transmission
DNA for resistance
Passed in by conjunction

Question 4

Mutation in genes for p35 can cause cancer explain how

Answer 4

Cancer oftens have damaged DNA
P53 faulty/ not made
Cell with faulty DNA divides
Uncontrolled division produces cancer

Question 5

A fish uses its gills to absorb o2 from water.explain how

Answer 5

Large surface area provided by lamellae
Increases diffusion
Thin epithilium/distance between water and blood
Counter current of blood and water
Maintains conc gradient
As water is always next to blood with lower oxygen conc
Circulation replaced blood saturated with oxygen
Ventilation replaces water

Question 6

Conclusions drawn from table about deformed frog legs

Answer 6

Worms cause deformed legs
Deformed legs in 500um mesh cages 
Run off doesn't cause deformed legs 
No deform at 75um and run off
Run off makes effect of words worse