Selina Textbook Solutions: Nervous System | Biology Class 8 ICSE PDF Download

 Page 1


Nervous System 
REVIEW QUESTIONS 
Multiple Choice Questions: 
1. Put a tick mark (?) against the correct alternative in the following statements: 
(a) Medulla oblongata controls 
1. Smelling 
2. Beating of heart and respiratory movement 
3. Intelligence and will power 
4. Balancing the body 
(b) Balance of body is controlled by: 
1. Spinal cord 
2. Cerebellum 
3. Cerebrum 
4. Medulla 
(c) The smell of good food causes watering of your mouth. It is a 
1. Natural reflex 
2. Acquired relfex 
3. Inborn reflex 
4. Ordinary reflex 
(d) The structural and functional unit of nervous system is a 
1. Axon 
2. Nephron 
3. Neuron 
4. Texon 
Short Answer Questions: 
Question 1. 
Name the two types of coordination which take place in our body. 
Answer: 
(a) Nervous coordination: By nerves and brain 
(b) Chemical coordination: By hormones 
Page 2


Nervous System 
REVIEW QUESTIONS 
Multiple Choice Questions: 
1. Put a tick mark (?) against the correct alternative in the following statements: 
(a) Medulla oblongata controls 
1. Smelling 
2. Beating of heart and respiratory movement 
3. Intelligence and will power 
4. Balancing the body 
(b) Balance of body is controlled by: 
1. Spinal cord 
2. Cerebellum 
3. Cerebrum 
4. Medulla 
(c) The smell of good food causes watering of your mouth. It is a 
1. Natural reflex 
2. Acquired relfex 
3. Inborn reflex 
4. Ordinary reflex 
(d) The structural and functional unit of nervous system is a 
1. Axon 
2. Nephron 
3. Neuron 
4. Texon 
Short Answer Questions: 
Question 1. 
Name the two types of coordination which take place in our body. 
Answer: 
(a) Nervous coordination: By nerves and brain 
(b) Chemical coordination: By hormones 
Question 2. 
Your are driving your bicycle at a fast speed. Suddenly, a small boy comes in front of 
your cycle and, without wasting any time in thinking, you immediately apply the brakes 
and accident is avoided. What name is given to such an action? 
Answer: 
Reflex action (acquired). 
Question 3. 
Given below is the diagram of a neuron. Name the parts numbered 1-5. 
 
Answer: 
1. Dendrite 
2. Nucleus 
3. Cell Body (Nyton) 
4. Axon (Nerve fibre) 
5. Node of Ranvier 
Question 4. 
Write one word in the space provided to complete the second pair of the related words 
pertaining to nervous system. 
Memory : cerebrum : : breathing : 
Balance : cerebellum : : reasoning : 
Answer: 
Memory : cerebrum : : breathing: medulla oblongata 
Balance : cerebellum : : reasoning : cerebrum 
Question 5. 
Differentiate between the following pair of terms: 
(a) Stimulus and impulse 
(b) Receptor and effector 
(c) Motor nerve and sensory nerve 
Answer: 
(a) Stimulus: Any change in the environment that usually results in change in the 
activity of the body. 
Impulse: A wave of electrical disturbance that runs through the nerves. 
Page 3


Nervous System 
REVIEW QUESTIONS 
Multiple Choice Questions: 
1. Put a tick mark (?) against the correct alternative in the following statements: 
(a) Medulla oblongata controls 
1. Smelling 
2. Beating of heart and respiratory movement 
3. Intelligence and will power 
4. Balancing the body 
(b) Balance of body is controlled by: 
1. Spinal cord 
2. Cerebellum 
3. Cerebrum 
4. Medulla 
(c) The smell of good food causes watering of your mouth. It is a 
1. Natural reflex 
2. Acquired relfex 
3. Inborn reflex 
4. Ordinary reflex 
(d) The structural and functional unit of nervous system is a 
1. Axon 
2. Nephron 
3. Neuron 
4. Texon 
Short Answer Questions: 
Question 1. 
Name the two types of coordination which take place in our body. 
Answer: 
(a) Nervous coordination: By nerves and brain 
(b) Chemical coordination: By hormones 
Question 2. 
Your are driving your bicycle at a fast speed. Suddenly, a small boy comes in front of 
your cycle and, without wasting any time in thinking, you immediately apply the brakes 
and accident is avoided. What name is given to such an action? 
Answer: 
Reflex action (acquired). 
Question 3. 
Given below is the diagram of a neuron. Name the parts numbered 1-5. 
 
Answer: 
1. Dendrite 
2. Nucleus 
3. Cell Body (Nyton) 
4. Axon (Nerve fibre) 
5. Node of Ranvier 
Question 4. 
Write one word in the space provided to complete the second pair of the related words 
pertaining to nervous system. 
Memory : cerebrum : : breathing : 
Balance : cerebellum : : reasoning : 
Answer: 
Memory : cerebrum : : breathing: medulla oblongata 
Balance : cerebellum : : reasoning : cerebrum 
Question 5. 
Differentiate between the following pair of terms: 
(a) Stimulus and impulse 
(b) Receptor and effector 
(c) Motor nerve and sensory nerve 
Answer: 
(a) Stimulus: Any change in the environment that usually results in change in the 
activity of the body. 
Impulse: A wave of electrical disturbance that runs through the nerves. 
(b) Receptor: The nerve cell on receiving the stimulus sets up the waves of impulses 
towards the central nervous system. 
Effector: Any muscle or gland on receiving the impulse from the brain (or the spinal 
cord), contracts or secretes. 
(c) Motor nerve: It contains only motor neurons, 
Example: Nerves going to the muscles of the eyeball. 
Sensory nerve: It contains only sensoiy neurons. 
Example: optic nerve of the eye. 
Question 6. 
(a) Name the three major divisions of the human nervous system. 
(b) Name the three main parts of human brain. 
Answer: 
(a) 
1. The central nervous system (brain and spinal cord) 
2. The peripheral nervous system 
3. The autonomic nervous system 
(b) 
1. Cerebrum 
2. Cerebellum 
3. Medulla oblongata 
Question 7. 
Give the function of each of the following: 
(a) Olfactory nerve: 
(b) Optic nerve: 
(c) Facial nerve: 
Answer: 
(a) Olfactory nerve: The sense of smell is present in the epithelial layers of the nasal 
chambers. The sense of smell is carried to the brain by the olfactory nerve. They arise 
from the anterior ends of the olfactory lobes and are distributed to lining of nasal 
chambers. 
(b) Optic nerve: It carries the reflection of the object from the retina to the brain. The 
image formed on the retina is in a reverted position and the correct picture is formed in 
the brain as the object is. The optic nerves arise from the side of diencephalon. They 
innervate the retina of the eye and are sensory in nature. 
(c) Facial nerve: It carries message and all expressions of the face, mastication work 
alone by the teeth, movement of the neck and the activities of the salivary glands to the 
brain. It arises from the side of medulla. On the whole facial nerves are mixed in nature. 
Page 4


Nervous System 
REVIEW QUESTIONS 
Multiple Choice Questions: 
1. Put a tick mark (?) against the correct alternative in the following statements: 
(a) Medulla oblongata controls 
1. Smelling 
2. Beating of heart and respiratory movement 
3. Intelligence and will power 
4. Balancing the body 
(b) Balance of body is controlled by: 
1. Spinal cord 
2. Cerebellum 
3. Cerebrum 
4. Medulla 
(c) The smell of good food causes watering of your mouth. It is a 
1. Natural reflex 
2. Acquired relfex 
3. Inborn reflex 
4. Ordinary reflex 
(d) The structural and functional unit of nervous system is a 
1. Axon 
2. Nephron 
3. Neuron 
4. Texon 
Short Answer Questions: 
Question 1. 
Name the two types of coordination which take place in our body. 
Answer: 
(a) Nervous coordination: By nerves and brain 
(b) Chemical coordination: By hormones 
Question 2. 
Your are driving your bicycle at a fast speed. Suddenly, a small boy comes in front of 
your cycle and, without wasting any time in thinking, you immediately apply the brakes 
and accident is avoided. What name is given to such an action? 
Answer: 
Reflex action (acquired). 
Question 3. 
Given below is the diagram of a neuron. Name the parts numbered 1-5. 
 
Answer: 
1. Dendrite 
2. Nucleus 
3. Cell Body (Nyton) 
4. Axon (Nerve fibre) 
5. Node of Ranvier 
Question 4. 
Write one word in the space provided to complete the second pair of the related words 
pertaining to nervous system. 
Memory : cerebrum : : breathing : 
Balance : cerebellum : : reasoning : 
Answer: 
Memory : cerebrum : : breathing: medulla oblongata 
Balance : cerebellum : : reasoning : cerebrum 
Question 5. 
Differentiate between the following pair of terms: 
(a) Stimulus and impulse 
(b) Receptor and effector 
(c) Motor nerve and sensory nerve 
Answer: 
(a) Stimulus: Any change in the environment that usually results in change in the 
activity of the body. 
Impulse: A wave of electrical disturbance that runs through the nerves. 
(b) Receptor: The nerve cell on receiving the stimulus sets up the waves of impulses 
towards the central nervous system. 
Effector: Any muscle or gland on receiving the impulse from the brain (or the spinal 
cord), contracts or secretes. 
(c) Motor nerve: It contains only motor neurons, 
Example: Nerves going to the muscles of the eyeball. 
Sensory nerve: It contains only sensoiy neurons. 
Example: optic nerve of the eye. 
Question 6. 
(a) Name the three major divisions of the human nervous system. 
(b) Name the three main parts of human brain. 
Answer: 
(a) 
1. The central nervous system (brain and spinal cord) 
2. The peripheral nervous system 
3. The autonomic nervous system 
(b) 
1. Cerebrum 
2. Cerebellum 
3. Medulla oblongata 
Question 7. 
Give the function of each of the following: 
(a) Olfactory nerve: 
(b) Optic nerve: 
(c) Facial nerve: 
Answer: 
(a) Olfactory nerve: The sense of smell is present in the epithelial layers of the nasal 
chambers. The sense of smell is carried to the brain by the olfactory nerve. They arise 
from the anterior ends of the olfactory lobes and are distributed to lining of nasal 
chambers. 
(b) Optic nerve: It carries the reflection of the object from the retina to the brain. The 
image formed on the retina is in a reverted position and the correct picture is formed in 
the brain as the object is. The optic nerves arise from the side of diencephalon. They 
innervate the retina of the eye and are sensory in nature. 
(c) Facial nerve: It carries message and all expressions of the face, mastication work 
alone by the teeth, movement of the neck and the activities of the salivary glands to the 
brain. It arises from the side of medulla. On the whole facial nerves are mixed in nature. 
Long answer questions 
Question 1. 
With the help of a suitable diagram describe the structures of a neuron. 
Answer: 
Nervous system consists of special cells called nerve cells or neurons. It has a main cell 
body called cyton. It gives out many processes called dendrites. From it a very long 
process is given out. It is called axon or nerve fibre. 
 
The cell body has a nucleus. The dendrites get the message from the organs and send 
this message to the axon through the cell body. Then the axon sends the message to 
muscles to contrast or to the gland for secretion. 
The neurons make contact with one another through their processes. The axon at its 
end branches and meets the dendrites of another neuron. The meeting point is called 
synapse. The message is passed on from one axon to the dendrites of another neuron. 
How the message goes ? It is like this: 
Organ ? Message goes to dnedrites ? Cell body ? Axon ? Muscles or glands 
Question 2. 
Briefly describe the structure of the cerebrum in human brain and mention its functions. 
Answer: 
Brain consists of main three parts and lies in the cranial cavity of skull. 
Page 5


Nervous System 
REVIEW QUESTIONS 
Multiple Choice Questions: 
1. Put a tick mark (?) against the correct alternative in the following statements: 
(a) Medulla oblongata controls 
1. Smelling 
2. Beating of heart and respiratory movement 
3. Intelligence and will power 
4. Balancing the body 
(b) Balance of body is controlled by: 
1. Spinal cord 
2. Cerebellum 
3. Cerebrum 
4. Medulla 
(c) The smell of good food causes watering of your mouth. It is a 
1. Natural reflex 
2. Acquired relfex 
3. Inborn reflex 
4. Ordinary reflex 
(d) The structural and functional unit of nervous system is a 
1. Axon 
2. Nephron 
3. Neuron 
4. Texon 
Short Answer Questions: 
Question 1. 
Name the two types of coordination which take place in our body. 
Answer: 
(a) Nervous coordination: By nerves and brain 
(b) Chemical coordination: By hormones 
Question 2. 
Your are driving your bicycle at a fast speed. Suddenly, a small boy comes in front of 
your cycle and, without wasting any time in thinking, you immediately apply the brakes 
and accident is avoided. What name is given to such an action? 
Answer: 
Reflex action (acquired). 
Question 3. 
Given below is the diagram of a neuron. Name the parts numbered 1-5. 
 
Answer: 
1. Dendrite 
2. Nucleus 
3. Cell Body (Nyton) 
4. Axon (Nerve fibre) 
5. Node of Ranvier 
Question 4. 
Write one word in the space provided to complete the second pair of the related words 
pertaining to nervous system. 
Memory : cerebrum : : breathing : 
Balance : cerebellum : : reasoning : 
Answer: 
Memory : cerebrum : : breathing: medulla oblongata 
Balance : cerebellum : : reasoning : cerebrum 
Question 5. 
Differentiate between the following pair of terms: 
(a) Stimulus and impulse 
(b) Receptor and effector 
(c) Motor nerve and sensory nerve 
Answer: 
(a) Stimulus: Any change in the environment that usually results in change in the 
activity of the body. 
Impulse: A wave of electrical disturbance that runs through the nerves. 
(b) Receptor: The nerve cell on receiving the stimulus sets up the waves of impulses 
towards the central nervous system. 
Effector: Any muscle or gland on receiving the impulse from the brain (or the spinal 
cord), contracts or secretes. 
(c) Motor nerve: It contains only motor neurons, 
Example: Nerves going to the muscles of the eyeball. 
Sensory nerve: It contains only sensoiy neurons. 
Example: optic nerve of the eye. 
Question 6. 
(a) Name the three major divisions of the human nervous system. 
(b) Name the three main parts of human brain. 
Answer: 
(a) 
1. The central nervous system (brain and spinal cord) 
2. The peripheral nervous system 
3. The autonomic nervous system 
(b) 
1. Cerebrum 
2. Cerebellum 
3. Medulla oblongata 
Question 7. 
Give the function of each of the following: 
(a) Olfactory nerve: 
(b) Optic nerve: 
(c) Facial nerve: 
Answer: 
(a) Olfactory nerve: The sense of smell is present in the epithelial layers of the nasal 
chambers. The sense of smell is carried to the brain by the olfactory nerve. They arise 
from the anterior ends of the olfactory lobes and are distributed to lining of nasal 
chambers. 
(b) Optic nerve: It carries the reflection of the object from the retina to the brain. The 
image formed on the retina is in a reverted position and the correct picture is formed in 
the brain as the object is. The optic nerves arise from the side of diencephalon. They 
innervate the retina of the eye and are sensory in nature. 
(c) Facial nerve: It carries message and all expressions of the face, mastication work 
alone by the teeth, movement of the neck and the activities of the salivary glands to the 
brain. It arises from the side of medulla. On the whole facial nerves are mixed in nature. 
Long answer questions 
Question 1. 
With the help of a suitable diagram describe the structures of a neuron. 
Answer: 
Nervous system consists of special cells called nerve cells or neurons. It has a main cell 
body called cyton. It gives out many processes called dendrites. From it a very long 
process is given out. It is called axon or nerve fibre. 
 
The cell body has a nucleus. The dendrites get the message from the organs and send 
this message to the axon through the cell body. Then the axon sends the message to 
muscles to contrast or to the gland for secretion. 
The neurons make contact with one another through their processes. The axon at its 
end branches and meets the dendrites of another neuron. The meeting point is called 
synapse. The message is passed on from one axon to the dendrites of another neuron. 
How the message goes ? It is like this: 
Organ ? Message goes to dnedrites ? Cell body ? Axon ? Muscles or glands 
Question 2. 
Briefly describe the structure of the cerebrum in human brain and mention its functions. 
Answer: 
Brain consists of main three parts and lies in the cranial cavity of skull. 
1. The cerebrum 
2. The cerebellum 
3. The medulla oblongata 
Cerebrum: It is very large and form two third of the whole brain. The two hemispheres 
are separated from each other by a deep longitudinal groove, the median fissure. The 
outer surface is folded with ridges and grooves. The hemispheres are hollow from inside 
and their walls have outer and inner portions. The outer portion has cell bodies of the 
neurons and it is called grey matter. 
The wavery edges of the folded layer has large number of neurons to the extent of nine 
billion. The inner portion of the cerebrum has axons and it is called white matter. 
Functions: 
1. It controls all the voluntary activities. 
2. It is the seat of intelligence, consciousness and will power. 
Question 3. 
Mention the three functions of spinal cord. 
Answer: 
Spinal cord has the following functions. 
1. It is the centre of reflex actions below the neck. 
2. It carries messages from the skin and muscles to the brain. 
3. All the stimuli and responses are passed from and to the brain through the spinal 
cord. 
Question 4. 
With the help of suitable example, describe reflex action. 
Answer: 
Reflex action: Reflex actions are automatic responses to stimuli. These actions are not 
under the control of the animal. They are of definite and mechanical type. Peripheral 
nervous system and spinal cord both control certain action and the brain is not in action. 
Some examples of reflex actions are: 
1. Pupil becomes narrow when strong light falls on it. 
2. The aroma of the food makes the mouth watering. 
3. The hand is withdrawn as we touch the hot plate. 
4. Flow of bile from the gall bladder into the duodenum. 
5. A loud thud may lead to opening of the mouth. 
In a reflex action brain is not involved, removing the hand on touching a hot plate is a 
reflex action. The impulse of heat goes from the hand to the spinal cord and the order is 
sent back to the muscles of the hand to remove the hand from the hot plate.