NIOS Class 10 Science Worksheet 23 Questions Answers – Control and Coordination

This Worksheet 23 contains questions based on Chapter 23 Control and Coordination complete answers.

This post explains the answers of questions given in the worksheet including explanation, diagrams. These solutions will help you complete your assignments and TMA also.

 

Control and Coordination Worksheet 23 Solution

Q1. With the help of a labelled diagram explain nerve cell.

Answer

A nerve cell is also called neuron. It is the structural and functional unit of the nervous system. Neuron helps in receiving, transmitting and passing messages (nerve impulse) from one part of the body to another.

Nerve cell has main three parts – (i) Dendrites (ii) Cell body(cyton) (iii) Axon

(i)       Dendrites -  These are branched structures coming out of the cell body. They receive the stimulus or impulse from sense organs or other neurons. The impulse creates a chemical reaction which produces an electrical signal.

(ii)    Cell body(cyton):- This part contains a nucleus and cytoplasm. It controls the activities of the neuron. It passes the impulses from dendrites to the axon.

(iii)    Axon :- It is a long fibre like part of the nerve cell. It carries nerve impulse away form the cell body. It is covered by a fatty insulating layer called neurilemma. The end of the axon has axon bulb which contain neurotransmitters or chemicals. These chemicals help in passing the impulse to the next neuron through synapse.

 

 

Q2. What is reflex action? Explain the mechanism of reflex action with a suitable example.

Answer

Reflex action

 Reflex action is completed by spinal cord. There is no role of brain in reflex action.  These involuntary actions are controlled by the spinal cord which takes place immediately without thinking. However impulse or input also goes to the brain. Mechanism of reflex action

Mechanism of Reflex Action

The pathway through which a reflex action takes place is called a reflex arc.

When a person touches a hot object, a sudden change occurs which acts as a stimulus. This stimulus(heat) is detected by the receptors present in the skin which sense the heat.

The message (impulse) is carried by the sensory neuron form the receptor to the spinal cord. The spinal cord which is the part of the central nervous system, quickly processes these messages without involving the brain.

After this, the impulse is sent back through a motor neuron form the spinal cord to the muscles of the hand. The muscles(effectors) immediately act and contract and the hand quickly removed from the hot object. This process happens quick and automatically and called a reflex action.

 

Q3. Draw a diagram of human brain and label cerebrum, cerebellum, medulla and fore brains on it.

Answer

Q4. When a barefoot person accidentally steps on a pin, what will be her/his immediate response? Explain how this reaction is processed by the nervous system?

Answer

When a barefoot person steps on a pin, the immediate response will be that the person quickly lifts or withdraws the foot from the pin. This is an involuntary action and happens without thinking. This response is called a reflex action.

Mechanism of the process

This reaction is processed through a reflex arc and it controlled by the spinal cord.

When a person steps on a pin, the pin prick acts as a stimulus.

This stimulus is detected by the pain receptors in the skin. The message (impulse) is carried by a sensory neuron form the skin to the spinal cord.

The spinal cord quickly processes the message without involving the brain after this the impulse is sent back through a motor neuron to the muscles of the leg or foot.

The message reaches the muscles(effectors) which immediately contract and the foot is quickly withdrawn form the pin. This whole process happens very fast and automatically to protect the body form injury.

 

Q5. Name the three major regions of human brain. Which part of brain maintains balance of body and coordinate muscular activity?

Answer

Three major regions of the human brains are :

    1. Cerebrum

    2. Cerebellum

    3. Medulla oblongata

The cerebellum maintains the balance of the body and coordinates muscular activities.

 

Q6. Differentiate between the following:

(i)    Sensory nerve and motor nerve

(ii)  Natural reflex and conditioned reflex

(iii)   Sympathetic and parasympathetic nervous system

Answer

Difference between Sensory Nerve and Motor Nerve

Sensory nerve	Motor nerve
Carries impulse from sense organ to brain or spinal cord	Carries impulse from brain or spinal cord to muscles or glands
Helps in receiving information	Helps in giving response or action

 

 

Difference between Natural reflex and Conditioned reflex

Natural reflex	Conditioned reflex
This is inborn	This is acquired
Does not need learning	Needs learning and experience
Example- breathing, blinking	Example- salivation,

Difference between Natural reflex and Conditioned reflex

Sympathetic Nervous system	Parasympathetic nervous system
Active during stress and emergency	Active during rest and normal conditions
Prepares body to fight	Brings body to normal relaxed state
Increase heart rate, dilates pupil under stress	Slows heart rate, digestion starts, body relaxes

 

Q7. Elucidate” the spinal cord is an integral part of the central nervous system”?

Answer

The spinal cord is an integral part of the central nervous system because it works together with the brain to control and coordinate the activities of the body. The central nervous system is made up of two main parts – (i) brain (ii) spinal cord.

The spinal cord extends from the medulla oblongata of the brain and runs down inside the vertebral column. It is protected by the three membrane –(i) duramater (ii) arachnoid (iii) pia mater and also contains cerebrospinal fluid which protects it form shocks.

Functions of spinal cord

i.   Controls reflex action

ii.    Carries sensory impulses form the body to brain

iii.   Transmits motor impulse form the brain to the muscles and glands

Therefore, the spinal cord is very important part of the nervous system.

 

Q8. Give one function performed by each of the following;

(i)     Cerebrum

(ii)   Cerebellum

(iii)   Hypothalamus

(iv)   Medulla oblongata

(v)       Cerebrospinal fluid

Answer

(i)    Functions of Cerebrum: - It controls thinking, memory, intelligence and voluntary actions. Examples- decision making, writing

(ii)    Functions of cerebellum: - It maintains balance of the body and coordinates muscular movements. Examples -walking, standing straight

(iii)  Functions of hypothalamus: -   It controls body temperature and maintain internal balance of the body. Example – regulation of hunger, thirst, sleep

(iv)   Functions of medulla oblongata: - It controls involuntary actions like breathing and heartbeat.

(v)     Functions of cerebrospinal fluid: - It protects the brain and spinal cord form shocks and helps in nourishment of nerve cells.

 

Q9. Define hormones. Name the hormone secreted by thyroid. Write its functions. Why doctor has advised us to use iodised salt in our food?

Answer

Hormones: - These are chemical substances secreted by endocrine glands. They are carried by blood and they control and regulate body activities.

Hormone secreted by thyroid gland: - Thyroxine

Functions of thyroxine hormone

i.     Controls the speed of metabolism

ii.    Helps in growth and development

iii.Regulates energy production

iv. Maintain proper w

Why doctors advise us to use iodised salt

Doctors advise the use of iodised slat because iodine is necessary for the production of thyroxine hormone. Lack of iodine cause iodine deficiency diseases like goitre and cretinism.

 

Q10. Write the functions of the hormone secreted by the endocrine gland pituitary. Name the hormone secreted by human testes. State its functions.

Answer

 

Pituitary gland is an important endocrine gland located at the base of the brain and secretes several hormones that control growth and development.

Functions of hormones

    1. Growth hormones (somatotropic hormone)- It controls growth of the body and development of bones. It helps in increase in height during childhood and adolescence.

    2. Gonad stimulating hormone: - It regulates the activity of gonads. It stimulates ovaries and testes to produce sex hormones. It helps in development of secondary sexual characters at puberty.

Testosterone is secreted by testes.

Functions of testosterone

i.     Helps in development of male secondary sexual characters like growth of beard and moustache, muscles development, deep voice

ii.  Helps in formation of sperms

iii.  Controls male reproductive functions

iv. Influence physical strength