IGCSE Biology 2.90 Insulation, sweating and shivering Topic Practice

Describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object.

[Maximum number: 4]

Neurones transmit nerve impulses.
The diagram shows a neurone.

(a)

This neurone is involved in the withdrawal reflex of a finger from a hot object. The neurone transmits electrical impulses from the central nervous system to the effector.

[ 4 ]

(i)

Draw a circle on the diagram to show the part of the neurone where the impulses are transferred to the effector.

[ 1 ]

(ii)

What is the name of this type of neurone?

association

motor

relay

sensory

[ 1 ]

(iii)

Explain the advantage of a withdrawal reflex when a finger touches a hot object.

[ 2 ]

[Maximum number: 8]

The diagram shows a human reflex arc with some structures labelled. It is the withdrawal reflex, which allows a person to remove their hand from a hot object quickly.

(a)

Which structure is the sensory receptor?

[ 1 ]

(b)

Which structure is the cell body of the relay neurone?

[ 1 ]

(c)

Which structure is the motor neurone?

[ 1 ]

(d)

Which structure is the effector?

[ 1 ]

(e)

A nerve impulse travels at 50 metres per second.

[ 4 ]

(i)

The length of the nerve pathway in the withdrawal reflex arc is 180 cm .

The time a person takes to remove their hand away from a hot object is called the response time.

Explain why the actual response time is different from the time taken for a nerve impulse to travel 180 cm .

[ 4 ]

[Maximum number: 1]

The diagram shows a food web from a woodland ecosystem.

Woodlice feed on dead and decaying plant material in the soil. The photographs show how a woodlouse can curl up into a ball.

This behaviour is an example of a reflex response.

State what is meant by a reflex response.

[Maximum number: 4]

Reflexes are responses that protect the body and involve the central nervous system (CNS).

If an animal steps on a sharp object, a reflex arc occurs so that it picks up its foot to prevent further damage.

Describe how named neurones bring about a withdrawal reflex to protect the animal from damage.

[Maximum number: 4]

A reflex is a rapid response to a stimulus.

The withdrawal of a hand when a finger touches a hot object is an example of a reflex.

Describe the pathway of a nerve impulse in the reflex arc involved in this response.

(a)

The diagram shows three types of neurone.

[ 6 ]

(i)

Give the names of these neurones.

A
B
C

[ 3 ]

(ii)

Explain the role of these neurones in the withdrawal reflex of a finger from a hot object.

[ 3 ]

[Maximum number: 4]

Humans can control their internal environment.

Coordination uses hormones and nerves.

Some responses are simple reflex arcs.
Describe the structure and functioning of the withdrawal reflex of a finger from a hot object.

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