Homeostasis

Question 1

Binding of insulin leads to an increase in the rate of respiration in cells such as osteoblasts.
Explain how.

Answer 1

1. (Insulin) leads to more transport proteins / channel (proteins) / carrier (proteins) for glucose;
2. More glucose (for respiration / glycolysis) enters cell;

Question 2

Scientists investigated the control of blood glucose concentration in mice. They kept a group of normal mice without food for 48 hours. After 48 hours, the blood glucose concentrations of the mice were the same as at the start of the experiment.
(a) Explain how the normal mice prevented their blood glucose concentration falling when they had not eaten for 48 hours.

Answer 2

1. Release of glucagon;
2. Leads to formation of glucose in liver (cells);
   Reject: glucagon breaks down glycogen, or any other biological molecule
3. From non-carbohydrates / amino acids / fatty acids.

Question 3

The scientists performed statistical tests on the data shown in the graph, to see whether the differences in the amount of mRNA in cells from normal and mutant mice were significant. Both the probability values they obtained were p<0.01.
Explain what this means about the differences in the amounts of mRNA produced.

Answer 3

1. Differences significant;
   Reject: references to results being significant once
2. Probability of difference being due to chance less than 0.01 / 1% / 1 in 100 / probability of difference not being due to chance more than 0.99 / 99% / 99 in 100.