Homeostasis prepared questions with answers

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1. Read the following sentences about negative feedback control and place them in the correct sequence.
A Nervous or hormonal messages are sent to effectors, via a control centre.
B Deviation from the norm is counteracted.
C Effectors bring about corrective changes.
D receptor detects a change in the internal environment.

2. Below are four different sets of graphs.
ldentify which graph, A, B, C or D, best shows the relationship between external temperature and body temperature for an endotherm and an ectotherm.

3. Below are pairs of statements about skin and temperature control. Read the statements and decide which statement of each pair goes into each column of the table. The first one has been done for you.

4. The graph below shows changes in a person's body temperature before, during and after certain events.

A) i) What is the normal body temperature of this person?
ii) What was the maximum temperature recorded during the investigation?
iii) How long did the exercise last?
B) i) Explain how sweating during period X could help to control body temperature.
ii) Explain how changes in the blood supply under the skin during period Y can help to control body temperature.

5. Study the diagram below and answer the questions in your notebook.

 
A) Which letters indicate the normal negative feedback control of body temperature? A and C; A and D; B and C; B and D.
B) Which situation, A, B, C or D, would be the immediate result of exposure to intense cold?

6. Look at the graph below that shows the relationship between blood glucose levels and the time after glucose was consumed.
Answer the following questions.

A) At what time:
i)did the person eat the glucose?
ii) was the blood glucose level at its highest?
iii) was the blood glucose level at its lowest?
B) What was the concentration of blood glucose:
i) at its highest level?
ii) at its lowest level?

7. Which one of the following responses would occur after eating a jam sandwich and drinking a can of cold drink?

a) A, D and E
b) B, C and E
c) A, C and E
d) A, C and F

8. Homeostasis is the maintenance of a constant:
A) blood temperature
B) external environment
C) internal environment
D) water content

9. During a race, an athlete's body temperature will begin to rise. Which changes will occur in the skin and to the skin and to the surface blood vessels to help return the body temperature to normal?

10. The diagram below shows a capillary in the skin of a mammal.

Which diagram shows what the capillary will look like when the mammal becomes hot?

11. The graph below shows the body temperature of a person before, during and after taking a cold bath. (The temperature of the bath water was 22 °C.)

A) For how long was the person in the bath?
B) Explain why the person's body temperature fell.
C)Explain the role played by the blood vessels in the skin in helping to return the body temperature to normal.

12. A) Why do body cells need glucose?
B) In healthy humans, the blood contains 60 -110 mg of glucose per 100 cm of blood. Which gland secretes the hormones that are responsible for keeping this level fairly constant?
C) The graph below shows the changes in blood glucose level after a meal.

Explain the shape of the graph between:
i) A and B
ii) B and C
iii) C and D
D) People with the disease sugar diabetes cannot make insulin. Why is it dangerous for diabetics to eat a meal containing a lot of sugar?
E) The regulation of blood glucose levels is one example of homeostasis. What is homeostasis, and why is it important?

13. A) Describe the principles of feedback mechanisms used in homeostasis.
B) Explain how the concentration of glucosein the blood is regulated by hormones.
C) Suggest and explain two problems that might occur in the body when the concentration of glucose in the blood cannot be controlled.

14. A) Describe how endotherms regulate their body temperature in cold conditions.
B) Explain how hypothermia can occur and describe how it can be prevented.

Answers

1. D ----> A ----> C ----> B

2. The answer is C. The curve for the endotherm remains constant, at about 37 °C, even though
the external temperature rises. The body temperature for the ectotherm increases as the external temperature increases.

3. Mechanisms to lower body temperature:
2. a)   3. a)   4. b)   5. b)   6. b)   7. a)   8. b)   9. a)   10. a)
Mechanisms to raise body temperature:
2. b)   3. b)  4. a)  5. a)    6. a)    7. b)    8. a)    9. b)  10. b) 

4. A) i)  36.9°C
ii) 38.1 °C
iii) 4 minutes
B) i) Sweating increases the rate of heat loss from the body. Sweat, containing water, is secreted by the sweat glands onto the surtace of the skin. As the water evaporates, heat is lost and the temperature decreases.
ii) Blood vessels near the surtace of the skin constrict, so less blood flows near the surface of the skin. This reduces the amount of heat that is lost by radiation from the blood to the air.

5. A)  B and C
B)  C

6. A) i) 10:15
ii) A few minutes before 11:00
iii) A few minutes after 11:30
B) i) 138 mg glucose/100 cm³ blood
ii) 86 mg glucose/100 cm³ blood

7. c) A, C and E
A jam sandwich and a can of cold drink contain a lot of sugar. Their ingestion would result in more glucose in the blood (A), the pancreas would respond by producing more insulin (C), and the liver would respond to more insulin in the blood by converting glucose into glycogen; there would be more glycogen (E).

8. C

9. B

10. B

11. A) 20 minutes
B) The person lost heat from his or her body to the cold water. His or her body temperature was 37°C, the water was only 22 °C.
C) The blood vessels constrict to decrease the blood supply to the skin, so less heat is lost to the surroundings.

12. A) Glucose is required for the process of respiration.
B) The pancreas
C) i) Between A and B, blood glucose level rises from 95 mg per 100 cm blood to 150 mg between 1 p.m. and 1:30 p.m. due to the absorption of glucose from the meal.
ii) Between B and C, the blood glucose level falls back to 95 mg per 100 cm' blood between 1:30 p.m. and 2 p.m. due to the release of insulin from the pancreas to restore the level.
iii) Between C and D, from 2 p.m. to 4 p.m., the blood glucose level in the blood remains relatively Constant at 95 mg per 100 cm blood. The level is Controlled by the release of insulin from the pancreas.
D) The blood glucose level could rise to a level that could damage cellIs, particularly brain cells.
E) Homeostasis is the maintenance of a constant internal environment. Homeostasis is important to enable all body activities to take place within narrowly determined optimum conditions.

13. A) The maintenance of a constant internal environment means that only a very narrow range of deviation from the norm is allowed. Any changes from the steady state are detected by a sensor. This signals to the brain how much change has occurred. The control system restores the steady state by means of an effector. Information is fed back to the sensor, which reverses its action. This is negative feedback.
B) The amount of carbohydrate eaten aftects the amount of glucose in the blood. The cells in the body need a constant supply of glucose for energy. Insulin is secreted by the lslets of Langerhans in the pancreas and causes the liver to convert excess glucose to glycogen. Another hormone, glucagon, stimulates the liver to convert glycogen to glucose. The nervous system is sensitive to the levels of biood glucose, which is normally 90-100 mg of glucose per 100 cm of blood. Adrenaline is also able to stimulate the conversion of glycogen to glucose.
C)The concentration of glucose can rise to a dangerous level when the excess glucose cannot be converted to glycogen. The kidneys are unable to reabsorb the excess glucose and glucose appears in the urine. This can lead to kidney damage. Insulin has to be injected into the bloodstream to stimulate the conversion of glucose to glycogern. The concentration of glucose can tall to dangerous levels. If the liver and muscles cannot build up stores of glycogen, there are no reserves of glycogen to convert to glucose. A lack of glucose can lead to diabetes mellitus.

14. A) In cold Conditions, the blood temperature may fall. This is detected by the hypothalamus that sends messages to the cells to increase heat production by shivering. The metabolic rate is also increased so that more heat is produced in the body. Messages also go to the skin that cause vasoconstriction of the blood capillaries so that less heat is lost by radiation.
B) Hypothermia can occur when the body temperature talls and the body's metabolism slows down. It can be prevented by eating hot food, drinking hot drinks, wearing warm clothing and being near a fire.

The end, posted by Miss Fang Xiu.