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IGCSE Biology Extended14.4.8—Maintenance of a constant internalTopic Practice

14.4.8—Maintenance of a constant internal

• Describe the maintenance of a constant internal body temperature in mammals in terms of vasodilation and vasoconstriction of arterioles supplying skin surface capillaries

Question 1(a)(iv)

[Maximum number: 3]

Homeostasis is the maintenance of a constant internal environment.

Human skin is involved in the maintenance of a constant internal body temperature.

Structure [ is a shunt vessel and E is an arteriole.

Describe how these blood vessels are involved in maintaining a constant internal body temperature in a cold environment.

Question 2(b)

[Maximum number: 3]

Describe the functions of arterioles in the skin.

Question 25

[Maximum number: 1]

The diagram shows some blood vessels near the surface of the skin.

Question image

If vasodilation occurs at X , what happens to the blood flow at Y and Z ?

Y

Z

decreases

decreases

decreases

stays constant

increases

increases

increases

stays constant

Question 27

[Maximum number: 1]

A person's skin looks more red in a warm environment than it does in a cool environment.
Which explanation is correct?

A

The arterioles supplying capillaries in the skin vasodilate and less blood flows to the skin surface.

B

The arterioles supplying capillaries in the skin vasodilate and more blood flows to the skin surface.

C

The arterioles supplying capillaries in the skin vasoconstrict and more blood flows to the skin surface.

D

The arterioles supplying capillaries in the skin vasoconstrict and less blood flows to the skin surface.

Question 27

[Maximum number: 1]

What describes how the body maintains a constant internal temperature on a hot day?

A

Vasoconstriction increases blood flow to the skin surface capillaries.

B

Vasoconstriction decreases blood flow to the skin surface capillaries.

C

Vasodilation increases blood flow to the skin surface capillaries.

D

Vasodilation decreases blood flow to the skin surface capillaries.

Question 28

[Maximum number: 1]

Which statement about the regulation of human body temperature is correct?

A

Vasoconstriction of skin arterioles occurs when the body temperature is too low.

B

Vasodilation of skin arterioles occurs when the body temperature is too low.

C

Vasoconstriction of skin capillaries occurs when the body temperature is too high.

D

Vasodilation of skin capillaries occurs when the body temperature is too low.

Question 6(b)(i)

[Maximum number: 3]

Fig. 6.1 is a flow chart of some of the events that occur to maintain a constant body temperature.

Fig. 6.1

Fig. 6.1

Describe how shunt vessels in the skin function to help cool the body when the body temperature is high.

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