June 2010

Question 1

Why does oestrogen only affect target cells, not affect other cells in the body

Answer 1

Other cells don’t have oestrogen receptors

Question 2

Give 2 characteristics of stem cells

Answer 2

Will replicate

Totipotent/not differentiated

Question 3

Explain why mitochondria inside slow muscle fibres are found near the cell membrane

Answer 3

Short distance for diffusion of oxygen

Oxygen used by mitochondria

Question 4

Explain how an optical microscope can be used to find the diameter of a muscle fibre

Answer 4

Measure field diameter with a scale

Estimate the number of fibres to cover diameter

Question 5

Give 2 precautions you should take when sampling muscle fibres and give reasons why

Answer 5

Choose at random to avoid bias

Sample large number to be representative

Question 6

Why is electrophoresis used in an experiment testing DNA

Answer 6

Separate the DNA pieces

Question 7

Explain how the resting potential is reestablished using ATP

Answer 7

Active transport

Of sodium out