1

1.Which of the following is closely associated with lowering of high body temperature?

A.Constriction of blood vessels in the skin

B.Vasodilation of blood vessels in the skin

C.Increased shivering

D.Decreased sweat production

(1)

2.Which cells secrete insulin?

A.b-cells of the pancreas

B.Cells of the liver

C.a-cells of the pancreas

D.Epithelial cells of the intestine

(1)

3.How do endocrine glands function when they are involved in homeostasis?

A.They release hormones directly into the blood system.

B.They release hormones through ducts to where they are used.

C.They release digestive enzymes from the pancreas.

D.They cause positive feedback in the bodys structures.

(1)

4.In thermoregulation, what would happen over a short period of time in each of these areas, if a person was placed in water at 15C ?

Peripheral circulation

Sweat glands

Liver

Skeletal muscle

A

Increased blood flow

Increased secretion

Decreased temperature

Decreased shivering

B

Decreased blood flow

Decreased secretion

Decreased temperature

Increased shivering

C

Decreased blood flow

Increased secretion

No change in temperature

Increased shivering

D

Decreased blood flow

Decreased secretion

No change in temperature

Increased shivering

(1)

5.The diagram shows how the body regulates glucose levels in the blood.

Glucose increase

Glucose normal

Glucose decrease

Y

released

X

released

What is Y?

A.Amylase

B.Insulin

C.Glucagon

D.Glycogen

(1)

6.Intravenous nutrition is used in patients who cannot feed by mouth. Introducing nutrients directly into veins bypasses the rate at which the digestive system absorbs them. Scientists studied the effect of injecting six different glucose concentrations into rats. They measured the glucose concentration in the urine per day and the glucose concentration in blood plasma per day. These values were compared to control rats that received the same six glucose concentrations through the mouth. The percentage of rats that died during the experiment (mortality) was measured. The results for all control rats orally fed with six different glucose concentrations were the same and are shown in the table below.

Urine glucose concentration /mmol dm3

Blood plasma glucoseconcentration / mmol dm3

Mortality / %

0

10

0

The results for the injected rats are shown in the line graph below.

(a)State the mortality for rats when injected with 110 mmol dm3 glucose.

zero / none died / 0 / 0%

(1)

(b)Estimate the difference in blood plasma glucose concentration between rats injected with 145 mmol dm3 glucose and the blood plasma glucose concentration of control rats orally fed 145 mmol dm3 glucose.

52 mmol dm3 - 10 mmol dm3 = 42 (1) mmol dm3 (units required)

(1)

(c)Using the data, explain the conclusions that can be drawn about the ability of the rats to regulate blood plasma glucose levels successfully.

intravenous after 85 mmol dm3, the glucose starts appearing in urine / glucose is no longer reabsorbed in kidneys / tubules;

up to 110 mmol dm3, the values in blood serum are close to normal / glucoseexcreted through urine / no mortality;

above 110 mmol dm3 / 115 mmol dm3, rats start dying / blood levels still close to normal / excreted through urine;

after 115 mmol dm3, values of glucose in blood / mortality startincreasing drastically;

(3)

(d)Suggest reasons for the differences between rats that were injected and the rats that were orally fed high levels of glucose concentrations.

the excess glucose in orally fed rats is egested / not absorbed;

in orally fed rats it enters body more gradually;

in orally fed rats it goes straight to liver while in injected rates it goes straightto rest of body;

in orally fed rats, insulin regulates blood sugar at all levels (10 mmol dm3);

2 max

(2)

(Total 7 marks)

7.(a)(i)Define the term homeostasis.

(i)homeostasis maintains the internal environment at a constantlevel / between narrow limits1

(1)

(ii)State which two systems are involved in the control of homeostasis.

(ii)nervous system and endocrine system1

Both are required for [1].

2

(1)

(b)Describe the roles of the kidney in homeostasis.

helps to maintain water balance (of the organism);

by retaining or excreting water;

helps to maintain blood pH;

excretion of urea / salts / gets rid of wastes;

2 max

(2)

(c)Using an example, explain the role of negative feedback in homeostasis.

a rise in level would feedback to decrease production;

as levels drop to low this would feedback to increase production;

eg blood glucose concentration / body temperature;3

Award [2 max] if example given is inappropriate.

(3)

(Total 7 marks)

8.The effect of different types of meals before exercise was tested on metabolism and performance for twelve competitive cyclists. The cyclists ingested either high fat or high carbohydrate meals before the start of exercise.

The test consisted of:1 hour of cycling at half peak power (pre-load)followed by five 10 minute incremental increases in intensity (load)and a 50 km time trial.

The concentration of various hormones in the blood plasma of the cyclists was measured. The graphs on the next page indicate the change in insulin and glucagon levels before and during the cycling test.

Pre-

load

Incremental

test (load)

50 km

time trial

Key:

High fat

High carbohydrate

80

60

40

30

20

15

10

5

3

240

200

160

120

100

80

60

50

40

30

20

Insulin concentration /

mU dm

(log scale)

Glucagon concentration /

ng dm

(log scale)

3

3

100

60

20

20

60

100

140

160

Test duration / min

[Source: Rowlands and Hopkins, International Journal of Sport Nutrition and Exercise Metabolism,(2002), 12, page 318]

Describe the changes in insulin concentration during the course of the exercise period for those cyclists who ate a high carbohydrate meal.

insulin levels at start of test are very high / 60 mU dm3;insulin levels decreased after exercise began;insulin levels reached a minimum level at the end of the exercise period / 5 mU dm3;insulin levels decreased most during the beginning of the pre-load period;insulin levels drop and then increases at a lower rate during pre-load period;2 max

(2)

(b)Compare the changes in insulin and glucagon concentration during the pre-load and incremental test period.

overall insulin levels decrease and glucagon increase (for both meals);preload insulin levels decreased (for both meals) while glucagon levels remainedconstant / decrease slightly (for high fat) / decreased (for high carbohydrate);insulin levels decreased during the incremental test while glucagon increased;final levels of insulin and glucagon at end of incremental test for both meals almost equal;

2 max

(2)

(c)Using the data provided, outline how the changes illustrate negative feedback of insulin and glucagon.

after meal glucose / fat levels increase causing insulin secretion;exercise decreases blood glucose levels causing glucagon levels to increase;in negative feedback, blood glucose levels that are higher / lower than the set point cause the pancreas to secrete insulin / glucagon;

2 maxAccept inverse statements.

(2)

(Total 6 marks)