B5 The Nervous System (page 59)

Question 1

Organisms need to respond to stimuli in order to survive, what do this mean?

Answer 1

Organisms need to respong to changes in the environment in order to survive.

Question 2

A singled-celled organism can just respond to its environment, but can multicelluar organisms do the same and why?

Answer 2

No, the cells of multicellular organisms need to communicate with each other first.

So as multicellular organisms evolved, they developed nervous and hormonal communication systems.

Question 3

The Nervous System detects and reacts to what?

Answer 3

Stimuli

Question 4

What do the Nervous System mean?

Answer 4

it means that Humans can react to their surroundings and coordinate their behaviour.

Question 5

The Nervous Systems is made up of different parts, name them?

Answer 5

Central Nervous System (CNS)
Sensory Neurones
Motor Neurones
Effectors

Question 6

Explain what the Central Nervous System (CNS) is?

Answer 6

In vertebrates (animals with backbones this consists of the brain and spinal cord only.

In mammals, the CNS is connected to the body by sensory neurones and motor neurones.

Question 7

Explain what the Sensory Neurones are?

Answer 7

The neurones that carry information as electrical impulses from the receptors to the CNS

Question 8

Explain what Motor Neurones are?

Answer 8

The neurones that carry electrical impulses from the CNS to effectors

Question 9

Explain what Effectors are?

Answer 9

All your muscles and glands, which respond to nervous impulses.

Question 10

Receptors and Effectors can form part simple or complex organs?

Answer 10

complex organs

Question 11

What are Receptors?

Answer 11

they are the cells that detect stimuli

Question 12

There are many different types of receptors, name some?

Answer 12

taste receptors on the tongue

sound receptors in the ears

Question 13

Receptors can form part of larger, complex organs, such as?

Answer 13

the retina of the eye is covered in light receptor cells.

Question 14

What are Effectors?

Answer 14

they respond to nervous impulses and bring about a change.

Question 15

Muscles and glands are known as what? and why?

Answer 15

effectors - they respond in different ways. Muscles contract in response to a nervous impulse, whereas glands secrete horemones.

Question 16

The Central Nervous System (CNS) is a coordination centre, explain what this is?

Answer 16

It receives information from the receptors and then coordinates a response (decides what to do about it). The response is carried out by effectors.

Question 17

A small bird is eating some seed, when out of the corner of its eye it spots a cat skulking towards it, what would this be called?

Answer 17

the stimulus (changes in the environment).

Question 18

The receptors in the birds eye are stimulated, what neurones carry the information from the receptors to the CNS?

Answer 18

Sensory neurones carry the informaion from the receptors to the central nervous system.

Question 19

What do the central nervous system do about the information from the sensory neurones regarding the bird?

Answer 19

the CNS decides what to do about it, then sends information to the muscles in the birds wings (the effectors) along motor neurones. The muscles contract and the bird flies away to safely.

see diagram on page 59

Dont forget its only large animals like mammals and birds that have complex nervous systems. Simple animals like jellyfish don’t - everything they co is a reflex response (see page 60).

Question 20

Name two types of effector? (2 marks)

Answer 20

Muscles (1 mark)
Glands (1 mark)