December Mock Exam Resit

Question 1

Give a definition of homeostasis.

Answer 1

the maintenance of a constant internal environment

Question 2

Explain why when a person is dehydrated, the cell volume of an osmoreceptor decreases.

Answer 2

• the water potential of the blood will decrease
• there is a higher water potential inside the osmoreceptor
• so water moves out by osmosis

Question 3

Describe and explain how the secretion of ADH affects urine produced by the kidneys.

Answer 3

• ADH increases a cell’s permeability to water
• so more water leaves the distal convoluted tubule
• smaller volume
• urine becomes more concentrated

Question 4

Give 2 factors that could affect the concentration of creatinine in the blood.

Answer 4

age, gender, muscle/body mass, ethnicity, exercise, kidney disease

Question 5

Explain how the normal mice prevented their blood glucose concentration falling when they had not eaten for 48 hours.

Answer 5

• release of glucagon
• leads to the formation of glucose
• glycogenolysis - the hydrolysis of glycogen stored in liver and muscle cells
• gluconeogenesis - formation of glucose from non-carbohydrate sources