Nervous System

Medulla oblongata controls:

1. Smelling
2. Beating of heart and respiratory movement
3. Intelligence and will power
4. Balancing of the Body

Answer

Beating of heart and respiratory movement

Reason — Involuntary functions of internal organs are controlled by Medulla oblongata.
Smelling is controlled by the olfactory part of the brain (olfactory bulb and cerebrum), not the medulla oblongata. Intelligence and will power are controlled by the cerebrum, which is responsible for thinking, memory, and decision-making. Balance and coordination are controlled by the cerebellum, not the medulla oblongata.

Spinal cord is an extension of:

1. Cerebellum
2. Cerebrum
3. Vertebral column
4. Medulla oblongata

Answer

Medulla oblongata

Reason — Medulla oblongata extends to form spinal cord that runs down to whole length of backbone.
The cerebellum is responsible for balance and coordination of movements, but it does not extend into the spinal cord. The cerebrum controls thinking, memory, and voluntary actions, and is not directly connected as an extension to the spinal cord. The vertebral column (backbone) is a bony structure that protects the spinal cord, not a part of the nervous system extension.

Body posture is maintained by:

1. Cerebrum
2. Cerebellum
3. Medulla oblongata
4. Spinal cord

Answer

Cerebellum

Reason — The function of cerebellum includes coordination of muscular activities and balancing of the body.
The cerebrum controls thinking, memory, intelligence, and voluntary actions, not body posture. The medulla controls involuntary actions like breathing and heartbeat, not posture. The spinal cord mainly conducts nerve impulses between the brain and body and helps in reflex actions, but it does not maintain posture.

Which of these is the largest part of the human brain ?

1. Cerebellum
2. Pons
3. Cerebrum
4. Medulla oblongata

Answer

Cerebrum

Reason — Cerebrum is the largest portion of the human brain.
The cerebellum is responsible for balance and coordination, but it is not the largest part of the brain. The pons is a part of the brainstem that helps in communication between different parts of the brain and controls some involuntary actions. The medulla oblongata controls involuntary activities like breathing and heartbeat, but it is not large in size.

Memory and intelligence are controlled by :

1. Cerebrum
2. Hypothalamus
3. Cerebellum
4. Midbrain

Answer

Cerebrum

Reason — The cerebrum is the seat of intelligence, memory, consciousness and will power. It controls all the voluntary activities.
The hypothalamus controls body temperature, hunger, thirst, and hormone regulation, not intelligence or memory. The cerebellum controls balance, posture, and coordination of movements, not cognitive functions like memory. The midbrain is involved in reflex actions related to vision and hearing, but not memory or intelligence.

Basic structural and functional unit of the nervous system is :

1. Nerve
2. Neuron
3. Axon
4. Nephron

Answer

Neuron

Reason — The basic structural and functional unit of the nervous system is the neuron.
A nerve is a bundle of many nerve fibers (axons of neurons). It is a structure made up of neurons, not the basic unit itself. An axon is only a part of a neuron that carries impulses away from the cell body. A nephron is the basic structural and functional unit of the kidney, not the nervous system.

The bony protective covering of the brain is :

1. Meninges
2. Pericardium
3. Pleura
4. Cranium

Answer

Cranium

Reason — Human brain is contained in, and protected by, a bony structure called the skull or the cranium.
Meninges are three protective membranes (dura mater, arachnoid mater, pia mater) that surround the brain and spinal cord, but they are not bony. Pericardium is the protective covering of the heart, not the brain. Pleura is the membrane surrounding the lungs, not the brain.

Which of the following structures is responsible in controlling the reflexes below the neck?

1. Vertebral column
2. Sensory neuron
3. Spinal cord
4. Motor neuron

Answer

Spinal cord

Reason — The Spinal cord is responsible in controlling the reflexes below the neck.
The vertebral column is the bony structure (backbone) that protects the spinal cord, but it does not control reflex actions. Sensory neurons carry signals from receptors to the spinal cord or brain, but they do not control reflexes by themselves. Motor neurons carry signals from the spinal cord to muscles, but they are not the control center for reflexes.

Which part of the brain coordinates our muscular activity ?

1. Cerebrum
2. Medulla oblongata
3. Cerebellum
4. None of the above

Answer

Cerebellum

Reason — The main function of the Cerebellum is to balance the body and coordinate muscular activities.
The cerebrum controls thinking, memory, intelligence, and voluntary actions, but it does not mainly coordinate muscle activity. The medulla controls involuntary actions like heartbeat and breathing, not muscular coordination.

The point of contact between two nerve cells is termed as :

1. Synaptic cleft
2. Association neuron
3. Synapse
4. Mixed nerve

Answer

Synapse

Reason — The terminal branches of the axon of one neuron lie very close to the dendrites of another neuron. This point of contact is called a synapse.
The synaptic cleft is only the small gap between two neurons at the synapse, not the entire point of contact. An association neuron (interneuron) is a type of neuron found in the brain and spinal cord, not the junction between two nerve cells. A mixed nerve contains both sensory and motor fibers, not related to the connection between two neurons.

Assertion (A): The life of living beings is dependent on a number of processes going on in their bodies like digestion, respiration, etc. All these processes are inter-related to fulfil the general needs of the body.

Reason (R): Living beings obtain the simplest forms of food after digestion and this digested food is burnt during respiration which provides energy. So, only two processes — digestion and respiration are enough for the survival of living beings.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is true but R is false.

Reason — A is true as living organisms depend on many interrelated life processes such as digestion, respiration, circulation, excretion, etc. These processes work together to maintain life.
R is false as although digestion provides simpler food and respiration releases energy from it, it is incorrect to say that only digestion and respiration are enough for survival. Other processes like transport (circulation) and excretion are also essential for survival.

Therefore, A is true but R is false is the correct option.

Assertion (A): Nervous system and chemical coordination in human beings are functionally related to each other.

Reason (R): Nervous coordination is mainly regulated by brain, spinal cord, nerves and sense organs whereas chemical coordination is controlled by the chemical messengers called hormones. They both work in proper coordination.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as the nervous system and chemical coordination are functionally related because both systems work together to regulate and control body activities.
R is true as nervous coordination is controlled by the brain, spinal cord, nerves, and sense organs, while chemical coordination is controlled by hormones released by endocrine glands. These two systems work in coordination to maintain proper functioning of the body.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion (A): The terminal branches of the axon of one neuron lie very close to the dendrites of another neuron.

Reason (R): : If there were a big gap between the axon and dendrites of two connecting neurons, impulses or messages would not be transmitted from one part of the body to another.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as the axon terminals of one neuron are located very close to the dendrites of another neuron, forming a synapse. This close arrangement allows nerve impulses to be transmitted efficiently.
R is true as if there were a large gap between the axon and dendrites, nerve impulses could not be effectively transmitted from one neuron to another, disrupting communication in the body.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion (A): The cerebrum is the seat of intelligence, consciousness and will power. It controls all voluntary activities of the body.

Reason (R): Cerebrum is the largest portion of the brain which accomodates a large number of neurons. Hence, it controls all the internal and external activities of the body, whether voluntary or involuntary.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is true but R is false.

Reason — A is true as the cerebrum is responsible for intelligence, consciousness, will power, and it controls voluntary activities like movement, thinking, and decision-making.
R is false as although the cerebrum is the largest part of the brain and has many neurons, it does not control all activities.

Therefore, A is true but R is false is the correct option.

Assertion (A): Sympathetic and parasympathetic systems are the two parts of autonomic nervous system which are independent in their functioning and are not related to each other at all.

Reason (R): Both of these nervous systems are opposite in their actions. Sympathetic nervous system accelerates the actions while parsympathetic system relaxes them.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is false but R is true.

Reason — A is false as the sympathetic and parasympathetic systems are not independent and unrelated. They are closely connected parts of the autonomic nervous system and work in coordination to maintain balance (homeostasis) in the body.
R is true as the sympathetic nervous system generally accelerates body activities (e.g., increases heart rate, breathing), while the parasympathetic nervous system slows down or relaxes these activities. Their actions are opposite.

Therefore, A is false but R is true is the correct option.

Match the terms given in column A with those of column B .

Answer

Correct the following statements by changing the first and the last word only :

1. Cerebrum maintains the balance of the body.
2. The long process which extends from the cell body of a neuron is termed as a dendron.
3. Enzymes regulate chemical coordination of the body.
4. Motor neurons carry impulses from the sense organs to the central nervous system.
5. Spinal cord regulates the heart beat and breathing movements.

Answer

1. Cerebellum maintains the balance of the body.

2. The long process which extends from the cell body of a neuron is termed as an axon.

3. Hormones regulate chemical coordination of the body.

4. Sensory neurons carry impulses from the sense organs to the central nervous system.

5. Medulla oblongata regulates the heart beat and breathing movements.

Write one word in the space provided to complete the second pair of the related words pertaining to nervous system:

1. Memory : cerebrum :: breathing : ...............

2. Balance : cerebellum :: reasoning : ...............

Answer

1. Memory : cerebrum :: breathing : medulla oblongata

2. Balance : cerebellum :: reasoning : cerebrum

Name :

1. Three main parts of the brain.
2. Three kinds of nerves.
3. Three kinds of neurons
4. Two divisions of the peripheral nervous system.

Answer

1. Cerebrum, Cerebellum, and Medulla oblongata
2. Sensory nerves, Motor nerves, and Mixed nerves
3. Sensory neurons, Motor neurons, and Association neurons
4. Somatic nervous system and Autonomic nervous system.

Define the following terms :

1. Coordination
2. Neuron
3. Synapse
4. Brain
5. Spinal cord

Answer

1. Coordination — The interlinking of various activities and organs of a living being as per the needs of the body internally or externally is called coordination.

2. Neuron — The nervous system is made up of special cells called nerve cells or neurons. Neurons are the structural and functional units of the nervous system. They help in transmitting information throughout the body as electrical and chemical signals.

3. Synapse — The terminal branches of the axon of one neuron lie very close to the dendrites of another neuron. This point of contact is called a synapse.

4. Brain — The brain along with the spinal cord forms our central nervous system. It is responsible for regulating all bodily functions, processing information from the senses, controlling movement, and enabling thought, emotions, and memory.

5. Spinal cord — The spinal cord extends from the medulla of the brain and runs down almost through the whole length of the backbone. It is a long, thin, tubular structure of nervous tissue that extends from the base of the brain down the back. It acts as a pathway for messages between the brain and the rest of the body.

Write one important role of the following :

1. Cerebellum
2. Medulla oblongata
3. Parasympathetic nervous system

Answer

1. Cerebellum — The main function of Cerebellum is to balance the body and coordinate muscular activities.

2. Medulla oblongata — Medulla oblongata controls the activities of the internal organs.

3. Parasympathetic nervous system — The parasympathetic nervous system re-establishes the normal conditions of the body after a fight or flight response. For example, if sympathetic nervous system increases the heart rate, parasympathetic nervous system relaxes it.

Mention the three functions of spinal cord.

Answer

The three functions of spinal cord are:

1. To control reflexes below the neck.
2. To conduct messages from the skin and muscles to the brain.
3. To conduct commands from the brain to muscles of the trunk and limbs

What are voluntary and involuntary actions? Which part of the nervous system controls them?

Answer

Voluntary actions — The actions or movements that are under the control of one's own will are called voluntary actions. For example, walking, jumping, lifting books, etc. Voluntary actions are controlled by Somatic nervous system.

Involuntary actions — The actions or movements that happen without consciousness or willingness of an individual are called the involuntary action. For example, beating of heart, breathing, digestion, etc. Involuntary actions are controlled by Autonomic nervous system.

Distinguish between the following pairs on the basis of the words indicated in the brackets [].

Sensory neuron and Motor neuron. [Function]

Answer

Differences between Sensory neuron and Motor neuron on the basis of function:

Distinguish between the following pairs on the basis of the words indicated in the brackets [].

Cerebrum and Cerebellum. [Location]

Answer

Differences between Cerebrum and Cerebellum on the basis of location:

Distinguish between the following pairs on the basis of the words indicated in the brackets [].

Cranial and Spinal nerves. [Structure of origin]

Answer

Differences between Cranial nerves and Spinal nerves on the basis of structure of origin:

Distinguish between the following pairs on the basis of the words indicated in the brackets [].

Sympathetic and Parasympathetic nervous system. [Function]

Answer

Differences between Sympathetic and Parasympathetic nervous system on the basis of function:

Distinguish between the following pairs on the basis of the words indicated in the brackets [].

Motor and Mixed nerves. [Kind of neurons]

Answer

Differences between Motor and Mixed nerves on the basis of kind of neurons:

Draw a neat and labelled diagram of a nerve cell.

Answer

Below diagram shows the structure of a nerve cell or neuron:

Given alongside is the figure of a median section of an organ. Study the same and answer the following questions :

1. Name the organ and write its location in our body.
2. Label the guidelines 1 to 4.
3. Write one important function of hypothalamus.
4. Which of the structures from 1 to 4 is considered as the master gland of the body ?
5. Mention the basic structural unit of the organ shown in the figure and the organ system to which it belongs.

Answer

1. The organ shown in the given figure is the human brain. It is contained in, and protected by, a bony structure called the skull or the cranium. The brain is further enclosed in three protective membranes, collectively called as meninges, which are separated by cerebrospinal fluid.

2. The guidelines 1 to 4 show:
   1 → Cereberal hemisphere
   2 → Cerebellum
   3 → Medulla Oblongata
   4 → Pituitary

3. One important function of the hypothalamus is regulating body temperature. It acts as the body's thermostat, monitoring internal temperature and initiating responses like sweating or shivering to maintain a stable internal environment.

4. The pituitary gland is often called the "master gland" of the human body because it produces hormones that regulate many other glands and bodily functions.

5. The basic structural and functional unit of the brain is the neuron (also known as a nerve cell). Neurons belong to the nervous system.

A part of our nervous system is shown alongside. Study the same and answer the following questions :

1. dentify the figure and name it.
2. Define the structure shown.
3. Label the part shown as X.
4. Write the name of the protective, tubular covering of the structure shown.
5. Mention the names of the three kinds of the structure that is shown in the figure.

Answer

1. The given figure shows a section of the Nerve.

2. A nerve refers to a bundle of axons (nerve fibres) enclosed in a tubular medullary sheath, that act as a pathway for transmitting information between the brain and other parts of the body, enabling sensation and movement.

3. The part "X" depicts Nerve fibres.

4. The protective, tubular covering is the Myelin Sheath.

5. Three kinds of nerves are:

   1. Sensory nerves
   2. Motor nerves
   3. Mixed nerves

Briefly describe the structure of the cerebrum in human brain and mention its functions.

Answer

Cerebrum is the largest portion of the brain. It is divided into two halves called the right and left cerebral hemispheres. Each hemisphere is internally hollow. The outer surface of the hemispheres is folded with ridges and grooves which increase the surface of the brain so as to accommodate a large number of neurons.

The cerebrum has following functions:

1. Intelligence
2. Consciousness
3. Will power
4. Memory

During Sports Day, Arnav ran a 200-meter race. After finishing, his breathing became fast and deep. A few minutes later, his breathing returned to normal even without him consciously trying. His teacher explained that this automatic adjustment was managed by a particular nervous system in the body.

(a) Name the specific division of the nervous system involved in this automatic control.

(b) State the two parts of this division.

(c) Write one important role of each part.

(d) Arnav's heartbeat and breathing rate increased during the race. Which gas was deficient in his blood at that moment?

(e) Mention the exact location of this nervous system within the body.

Answer

(a) The specific division of the nervous system involved in this automatic control is the Autonomic Nervous System (ANS).

(b) Sympathetic nervous system and Parasympathetic nervous system are the two parts of nervous system division.

(c) Sympathetic nervous system prepares the body for action during stress or exercise by increasing heart rate and breathing rate (fight-or-flight response).
Parasympathetic nervous system helps the body return to normal by slowing down heart rate and breathing rate (rest-and-digest response).

(d) The gas deficient in Arnav’s blood at that moment was oxygen.

(e) Autonomic Nervous System consists of a pair of chains of ganglia (a mass of cytons of nerve cells) and nerves found on either side of the spinal cord.