Chapter 23: CONTROL AND COORDINATION

Chapter 23: Control and Coordination Class 10 Science and Technology (212) NIOS Textbook Solutions

Chapter 23. CONTROL AND COORDINATION

INTEXT QUESTIONS 23.1

1. Can you think of a real-life example, when team work helped you to achieve something that you could not have done by yourself? Please write about this incidence in 3-5 sentences.

Answer: There is no single correct answer. There may be diverse examples. For instance, in farming, a group of people till the land, another group sows the seeds, someone else takes care of the crops and only then everyone enjoys the bounty of a good harvest.

2. Give one example of coordination of a process taking place in our body which is brought about by both the nervous system and hormonal system.

Answer: One example is the secretion of digestive juices. When food enters the stomach, the nervous system sends signals to start digestion, and hormones also stimulate the digestive glands to release digestive juices. Thus, both systems work together to digest food properly.

INTEXT QUESTIONS 23.2

1. The structural and functional unit of nervous system is (encircle the correct alternative out of the following)

(a) Nephron (b) Neuron (c) Synapse (d) Axon

Answer: (b) Neuron .

[ A neuron is the structural and functional unit of the nervous system because it receives and transmits nerve impulses throughout the body.]

2. Consider that you are passing by a garbage disposal area and you immediately cover your nose. Arrange the events below in a logical order by marking them from 1 to 5 to trace the events that happen in the nervous system from detection of foul smell (stimulus generation) to covering your nose (response).

(i) At the end of the axon, electrical impulse releases chemicals

(ii) Stimulus received on the dendritic cells of a neuron sets off chemical reaction that creates an electrical impulse

(iii) Electrical impulse transmitted through cell body and axon

(iv) The chemicals cross the synapse and reach the next neuron. Similarly, the electrical impulse crosses several neurons

(v) Finally, the impulse is delivered from neuron to the gland that helps in recognition of the foul smell and muscle cells that help in covering the nose.

Answer: (ii) → (iii) → (i) → (iv) → (v)

[ The stimulus is first received by dendrites, creating an electrical impulse. The impulse travels through the neuron, chemicals are released at the axon end, cross the synapse to the next neuron, and finally reach the muscles to cover the nose.]

3. With the help of a suitable example, explain the term ‘stimulus.’

Answer: A stimulus is an agent or environmental change that initiates a response in the body. For example, touching a hot object makes us immediately pull our hand away. Here, heat acts as the stimulus and pulling back the hand is the response.

INTEXT QUESTIONS 23.3

Fill in the blanks:

(i) The central nervous system consists of ________ and _____________.

(ii) The two functions of the cerebrum are _________ and ____________.

(iii) The major function of cerebellum is to maintain ________ of the body.

(iv) The ________________ part of brain controls the activity of all internal organs of our body.

(v) The outer and inner region of the cerebrum are composed of _______ and ___________ matter respectively.

Answer: (i) The central nervous system consists of brain and spinal cord.
(ii) The two functions of the cerebrum are intelligence and consciousness movement .
(iii) The major function of cerebellum is to maintain balance of the body.
(iv) The medulla ( medulla oblongata) part of brain controls the activity of all internal organs of our body.
(v) The outer and inner region of the cerebrum are composed of grey matter and white matter respectively.

INTEXT QUESTIONS 23.4

1. Name the two types of reflexes.

Answer: The two types of reflexes are :

(i) natural (inborn) reflexes and

(ii) conditioned (acquired) reflexes.

2. Given below are the different components of a reflex arc in a haphazard manner. Arrange them in the correct order in the space provided below:

Sensory neuron, Effector, Stimulus, CNS, Receptor, Response, Motor neuron

Answer: Stimulus → Receptor → Sensory neuron → CNS → Motor neuron → Effector → Response.

3. Now that you are aware of the well-thought out voluntary actions that are coordinated by the cerebrum and immediate response actions or reflex actions, coordinated by the spinal cord, try to identify whether the following situations may be best managed by well-thought out voluntary actions or quick response reflex actions. Please provide at least one reason for your choice.

Situation	Appropriate action voluntary action or reflex)	Reason for your choice
You need to immediately stop your bicycle as a speeding motorbike comes in front of your bicycle.
You have scored good marks in all the subjects in class X and now need to choose between science and commerce stream. Your family feels you should study science while you like numbers and would like to study commerce.
You are cleaning your cupboard, a sharp needle pokes you and you remove your hand immediately.
You have moved to a new neighborhood and are trying to make new friends.

Answer:

Situation	Appropriate action voluntary action or reflex)	Reason for your choice
You need to immediately stop your bicycle as a speeding motorbike comes in front of your bicycle.	Reflex Action	It is an emergency and there is no time to process information through the central nervous system.
You have scored good marks in all the subjects in class X and now need to choose between science and commerce stream. Your family feels you should study science while you like numbers and would like to study commerce.	Well thought out voluntary action	As the learner will have to live with the subject/ career choice that she/he makes, it is important to give priority to their individual choice. This decision should note made impulsively.
You are cleaning your cupboard, a sharp needle pokes you and you remove your hand immediately.	Reflex Action	It is an emergency and there is no time to process information through the central nervous system.
You have moved to a new neighborhood and are trying to make new friends.	Well thought out voluntary Action	It is important to choose friends who care for you and wish you well. Hence, it has to be a well thought out action.

INTEXT QUESTIONS 23.5

1. How many pairs of cranial nerves are present in our body?

Answer: There are 12 pairs of cranial nerves present in our body.

2. Name the two parts of autonomic nervous system.

Answer: The two parts of the autonomic nervous system are:

(i) Sympathetic nervous system

(ii) Parasympathetic nervous system

INTEXT QUESTIONS 23.6

1. Fill in the blanks:

(i) A hormone is transported by the …………………. to the target organ.

(ii) Hypoactivity of thyroid gland causes …………….. leading to cretinism in young children.

(iii) Pancreas secretes two hormones, which help in the …………. of glucose in our body.

Answer: (i) A hormone is transported by the Blood to the target organ.

(ii) Hypoactivity of thyroid gland causes goitre leading to cretinism in young children.

(iii) Pancreas secretes two hormones, which help in the metabolism of glucose in our body.

2. Each of the following statements has one correct response. Please choose the correct option and encircle it.

(i) If a pathologist were to collect a hormone, where would it be collected from?

(a) Blood (b) Brain  (c) Specific endocrine gland (d) Any part of the body

Answer: (a) Blood .

[Hormones are secreted by endocrine glands and transported through the blood to reach their target organs.]

(ii) Hyperactivity of the pituitary gland causes:

(a) Dwarfism  (b) Gigantism  (c) Cushing’s disease  (d) Cretinism.

Answer: (c) Cushing’s disease.

[ Hyperactivity of the anterior pituitary specifically refers to overproduction of ACTH  (adrenocorticotropic hormone), which stimulates the adrenal glands to produce excess cortisol, leading to Cushing's disease.]

(iii) The neurons that carry impulses from sense organs to the brain or spinal cord are:

(a) Sensory neuron (b) Motor neuron (c) Association neuron (d) Connecting neuron

Answer: (a) Sensory neuron.

[ Sensory neurons carry impulses from sense organs to the brain or spinal cord.]

(iv) The parts of a reflex are connected to:

(a) Brain (b) Spinal cord (c) Both brain and spinal cord (d) A synapse

Answer: (c) Both brain and spinal cord.

[ Reflex actions are mainly controlled by the spinal cord, but some reflexes may also involve the brain.]

(v) Two neurons are connected to each other through:

(a) Their axons

(b) Their dendrons

(c) The dendrites of the first neuron and the dendrites of the second one

(d) Synapse

Answer: (d) Synapse.

[ Two neurons are connected to each other through a synapse, which allows nerve impulses to pass from one neuron to another.]

(vi) An axon is:

(a) A nerve fibre (b) A bundle of dendrites (c) A bundle of nerve fibres (d) The sheath of a nerve fibre.

Answer: (a) A nerve fibre .

[ An axon is the long projection of a neuron that carries nerve impulses away from the cell body and it is called a nerve fibre.]

(vii) An individual reported to the neuro-physician with a body temperature much higher than normal. After several investigations, the neuro-physician diagnosed that a tumor in a specific area of the brain was causing this symptom. Where do you thing the tumor may have been located?

(a) Cerebrum (b) Cerebellum  (c) Hypothalamus (d) Diencephalon

Answer: (c) Hypothalamus.

[The hypothalamus regulates body temperature, hunger, thirst and other internal body functions. A tumour in this area can cause abnormal body temperature.]

(viii) Where is the subconscious mind located?

(a) Thalamus (b) Hypothalamus  (c) Cerebellum (d) Cerebrum

Answer: (c) Cerebellum .

[The cerebrum is associated with thinking, memory, intelligence, consciousness and subconscious activities. ]

(ix) Hyposecretion of insulin causes:

(a) Diabetes (b) Goitre  (c) Cretinism (d) Gigantism

Answer: (a) Diabetes

[Hyposecretion (less secretion) of insulin causes diabetes because blood glucose level increases in the body.]

(x) Which part of our brain helps in maintaining the balance of our body?

(a) Cerebrum (b) Cerebellum   (c) Medulla (d) Hypothalamus

Answer: (b) Cerebellum . 

[ The cerebellum helps in maintaining balance, posture and coordination of body movements.]

(xi) Sudha likes to sleep in and someone always has to wake her up in the morning. However, during exams she is able to get up without an alarm or any other help. Which part of the nervous system helps her to deal with this situation?

Sleep in- sleeping beyond waking hours

(a) Parasympathetic nervous system   (b) Medulla    (c) Sympathetic nervous system   (d) Cerebrum

Answer: (c) Sympathetic nervous system

[ During exams, stress activates the sympathetic nervous system (fight-or-flight), increasing alertness and arousal, which helps her wake up naturally without an alarm. The parasympathetic system promotes relaxation and sleep.]

TERMINAL EXERCISES

A. Tick the correct answer of the followings

1. The three protective coverings over the brain also called:

(A) Membranes    (B) Layers   (C) Meninges   (D) Sheaths

Answer: (C) Meninges

[ The three protective coverings of the brain and spinal cord are called the meninges (dura mater, arachnoid mater and pia mater).]

2. Which part of the brain controls the body temperature?

(A) Cerebrum    (B) Cerebellum     (C) Hypothalamus   (D) Medulla oblongata

Answer: (C) Hypothalamus .  

[The hypothalamus controls body temperature and helps maintain internal balance in the body.]

3. The spinal cord is extended from the medulla upto the whole length of the vertebral column and lies within the:

(A) Neural canal (B) Vertebral canal (C) Spinal canal (D) Eustachian canal

Answer: (B) Vertebral canal .

[The spinal cord extends from the medulla and lies within the vertebral canal of the vertebral column.]

4. Which one of the following hormones is secreted by the pancreas?

(A) Prolactin (B) Thyroxin (C) Adrenalin (D) Insulin

Answer: D) Insulin

[ The pancreas secretes insulin (and glucagon) to regulate blood sugar levels. Prolactin is from the pituitary, thyroxin from the thyroid and adrenalin from the adrenal glands.]

B. Answer briefly:

1. What is the nature of the membranes covering the brain? What is the name of the fluid that fills the space between these membranes? What is its role?

Answer: The brain is covered by three protective membranes called meninges. These membranes are tough and protective in nature. The space between the membranes is filled with cerebrospinal fluid (CSF). This fluid acts as a shock absorber, protects the brain from injury, and helps in supplying nutrients and removing waste materials.

2. Describe the three regions of the brain.

Answer: The brain has three main regions:

(a) Cerebrum: It is the largest part of the brain and is divided into right and left hemispheres. The outer gray matter contains neuron cell bodies, while the inner white matter contains nerve fibres. It is the seat of intelligence, consciousness, memory, reasoning, will-power and controls all voluntary actions.

(b) Cerebellum: It is located below the cerebrum and has an outer gray matter and inner white matter. Its main function is to maintain body balance and coordinate muscular activities, ensuring smooth and accurate movements.

(c) Medulla oblongata: It is the lowermost part of the brain and continues as the spinal cord. It controls involuntary activities such as breathing, heartbeat, movement of the alimentary canal and other vital functions of the body.

3. Differentiate between the following pairs of terms:

(i) Sensory nerve and motor nerve

(ii) Cerebrum and cerebellum.

(iii) Sympathetic and parasympathetic nervous system

Answer: (i) The difference between sensory nerve and motor nerve:

Sensory nerve	Motor nerve
Carries impulses from sense organs to the brain or spinal cord.	Carries impulses from the brain or spinal cord to muscles or glands.
Responsible for receiving stimuli.	Responsible for producing response.

(ii) The difference between cerebrum and cerebellum:

Cerebrum	Cerebellum
Largest part of the brain.	Smaller part located below the cerebrum.
Controls thinking, memory, intelligence and voluntary actions.	Maintains balance and coordinates muscular activities.

(iii) The difference between sympathetic and parasympathetic nervous system:

Sympathetic nervous system	Parasympathetic nervous system
Prepares the body for emergency situations.	Brings the body back to normal condition after stress.
Increases heart rate and body activity.	Slows heart rate and conserves energy.

4. Define the following terms:

(i) Receptor     (ii) Synapse    (iii) Hormone   (iv) Neuron    (v) Impulse  (vi) Stimulus    (vii) Effector

Answer: (i) Receptor: A receptor is a specialised cell or sense organ that receives a stimulus and sends signals to the nervous system.

(ii) Synapse : A synapse is the function of the branches of the axon of one neuron with the dendrites of another neuron.

(iii) Hormone : A hormone is a chemical secreted by an endocrine gland and carried by blood to a target organ situated elsewhere in the body to stimulate a specific activity.

(iv) Neuron: A neuron is the structural and functional unit of the nervous system that carries nerve impulses.

(v) Impulse: An impulse is an electrical signal that travels through neurons to transmit information.

(vi) Stimulus : A stimulus is an agent or an environmental change which can initiate a response in the body.

(vii) Effector: An effector is a muscle or gland that carries out the response after receiving signals from the nervous system.

5. Given below is a table regarding various hormones secreted by the pituitary gland and functions of these secretions. Fill in the blanks (1 to 4);

Hormones secreted                                            Functions

Somatotropic hormone                             ______________(1)____________

__________(2)____________                 Helps in the metabolism of glucose in our body

Thyroid hormone                                        ____________(3)__________

__________(4)_____________               In males it stimulates the secretion of testosterone.

Answer:

Hormones secreted	Functions
Somatotropic hormone	(1) Controls growth of bones and muscles (regulates body growth)
(2) Adrenocorticotrophic hormone (ACTH)	Helps in the metabolism of glucose in our body
Thyroid hormone	(3) Regulates basal metabolism and growth
(4) Luteinizing hormone (LH)	In males it stimulates the secretion of testosterone

6. Imagine that you did not score good marks in your science exam. Do you:

(a) tear the mark sheet and not let your parents know about it?

(b) decide that you are not a good student and cannot study science any further?

(c) discuss your mistakes with the teacher and ask for help from the teacher or another student who has done well and is willing to help you?

Please choose one of the three options above and provide two reasons for your choice

Answer: I would choose option (c) discuss your mistakes with the teacher and ask for help from the teacher or another student who has done well and is willing to help you.

Two reasons for this choice:

(i) It helps me understand my mistakes clearly so that I can improve in the next exam.

(ii) Getting guidance from teachers or classmates improves my learning and builds confidence instead of losing hope.

7. Imagine that you have gone out with three friends. One of them starts smoking and offers the cigarette to the rest of you. One of your friends accepts the offer hesitatingly and also encourages you to try smoking. One amongst you refuses to smoke and says that he did not know that he was in bad company. This person leaves the group in a huff. You also do not want to smoke but at the same

time you have been friends with this group for many years now and would like to continue your friendship.

Please describe in 2-4 sentences how you will communicate with your friends in an attempt to save your friendship without accepting their offer to smoke.

Please note: There is no single correct answer. The learner needs to demonstrate

use of assertive communication skills.

Answer: I will politely tell my friends that I do not want to smoke because it is harmful for health and I want to stay fit. I will make it clear that I respect their friendship but I cannot accept smoking. I will also suggest that we can still enjoy our time together by doing other healthy activities. This way, I can maintain friendship without compromising my values.

8. After a week, you go out again with the two friends who had asked you to try smoking a cigarette. This time they tell you that it is smart or stylish to smoke and in order to be part of the group, you should also smoke. Would you like to continue/ not continue being friends with them?

Please state your decision and provide at least two reasons for your decision.

Please note: There is no single correct answer. The purpose of this activity is to enable the learner to appreciate that friends never pressurize to do things that someone is uncomfortable with. The learner also needs to realize that exploitative relationships, including friendships should be terminated.

Answer: I would not continue being friends with them.

Two reasons for my decision:

(i) A true friendship should never force or pressure someone to do harmful things like smoking.

(ii) Smoking is dangerous for health and I do not want to get influenced into a bad habit just to fit in.

9. 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 is to quickly withdraw the foot.

This happens through a reflex action. The pain stimulus is detected by receptors in the skin, which send an impulse through a sensory neuron to the spinal cord. The spinal cord immediately sends a signal through a motor neuron to the leg muscles. The muscles contract and the foot is pulled away. This quick response happens without involving the brain initially, helping to protect the body from injury.

10. Give one function performed by each of the following:

1. Cerebrum

2. Cerebellum

3. Hypothalamus

4. Medulla oblongata

5. Cerebrospiral fluid

Answer:  1. Cerebrum: Controls voluntary actions and is responsible for thinking, memory and intelligence.

2. Cerebellum: Maintains balance of the body and coordinates muscular activities.

3. Hypothalamus: Regulates body temperature and controls hunger and thirst.

4. Medulla oblongata: Controls involuntary activities such as breathing and heartbeat.

5. Cerebrospinal fluid: Protects the brain and spinal cord by acting as a shock absorber.

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