NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination

NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination

Chapter 7 Control and Coordination NCERT Solutions for Class 10 Science will definitely useful in improving marks in the board examinations. Through the help of Class 10 Science NCERT Solutions, you can track your progress anytime and provide complete assistance. These NCERT Solutions are curated by our expert teachers who have vast experience of teaching students.

NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination

Chapter 7 Control and Coordination Class 10 Science NCERT Solutions


In Text Questions

Page No: 119

1. What is the difference between reflex action and walking?

Solution

Reflex Action Walking
It is the sudden action in response to something in the environment. It is a voluntary action controlled by brain involves central nervous system and spinal cord both.
It happens without thinking. It is affected by our thinking.
It occurs in a fraction of second. It occurs as a response by the brain through nerves cells so it take time.

2. What happens at the synapse between two neurons?

Solution

Synapse is a very small region that occurs between the last portion of axon of one neuron and the dendrite of the other neuron. It acts as a one-way passage in which transmission of nerve impulse can takes place in one direction only. At synapse, the nerve ending of a nerve cell converts the nerve impulse into some chemical substance that travels through the gap towards the dendrite of succeeding neuron. At the end of the axon, the electrical impulse sets off the release of some chemicals called neurotransmitters. These chemicals travel through the synapse and reach the dendrites of the successive neuron. These chemical messengers cross the synapse and start an electrical impulse.

3. Which part of the brain maintains posture and equilibrium of the body?

Solution

Cerebellum

4. How do we detect the smell of an agarbatti (incense stick)?

Solution

When the agarbatti burns, it produces vapours having a characteristic pleasant smell. This smell is detected by the olfactory receptors present inside our nose. The action of smell generates the electrical impulse. These impulses are carried to the sensory area of brain(forebrain-cerebrum). Thus we detect the smell of agarbatti.

5. What is the role of the brain in reflex action?

Solution

Reflex action takes place in the spinal cord. Only the information that a reflex action has taken place goes on to reach the brain.

Page No. 122

1. What are plant hormones?

Solution

The organic chemical substances produced in plants which control growth, development and responses in plants, are called plant hormones. The examples of plant hormones are Auxins, Gibberellins, Cytokinins and Abscisic acid.

2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Solution

Movement of leaves of the sensitive plant Movement of a shoot towards light
It is not a growth movement. It is a growth movement.
It is sensitive to touch. It is sensitive to light.
It is caused by the sudden loss of water from the swelling at the base of the leaves. It is caused by the unequal growth on two sides of the shoots.

3. Give an example of a plant hormone that promotes growth.

Solution

Auxin promotes growth of cells.

4. How do auxins promote the growth of a tendril around a support?

Solution

Auxin is a plant growth hormone. When the tip of a tendril touches a support, then the auxins (plant hormones) present in its tip move to that side of tip which is away from the support. Due to more auxins in it, the side of tendril away from the support grows faster and becomes longer than the side which is in contact with the support, and makes the tendril bend towards the support.

5. Design an experiment to demonstrate hydrotropism.

Solution

Materials Required:
Seed, A big container, Porous water pot, water and Sand.

hydrotropism

Procedure:
• The tray should be big enough to accommodate the porous pot.
• Fill the tray with sand and insert some seeds in it.
• Make a pit in the sand and insert the porous pot in it.
• Fill the porous pot with water.
• Leave the set up for about a week.

Observation:
After a week when seeds are taken out, it is observed that roots grow in the direction of the porous pot. This shows hydrotropic movement in roots.

Page No. 125

1. How does chemical coordination take place in animals?

Solution

Chemical coordination in animals takes place by the hormones. The hormones after secretion reach into blood and after that through blood, it reaches to the various parts of the body. For example, adrenaline which is secreted by adrenal gland and through blood it reaches to heart. Due to this, the heart beats faster in order to supply more oxygen to the muscles and the target organs get more oxygen and satisfies its need of oxygen to work. The hormones control and coordinate various functions of the body such as development, growth, sexual changes etc.

2. Why is the use of iodised salt advisable?

Solution

Iodine is necessary for the thyroid gland to make thyroxin hormone. Thyroxin regulates carbohydrate, protein and fat, metabolism in the body so as to provide the best balance for growth. A deficiency of iodine in the diet can cause a deficiency of thyroxine hormone in the body leading to a condition of enlarged thyroid gland called goiter characterised by swollen neck and an abnormally low level of thyroid hormones.

3. How does our body respond when adrenaline is secreted into the blood?

Solution

Adrenaline is secreted directly into the blood and is transported to different parts of the body. When secreted in large amount, it speeds up the heartbeat and hence supplies more oxygen to the muscles. The breathing rate also increases due to contraction of diaphragm and rib muscles. It also increases the blood pressure. All these responses enable the body to deal with any stress or emergency.

4. Why are some patients of diabetes treated by giving injections of insulin?

Solution

Insulin is a hormone secreted by pancreas that regulates the sugar level in the blood. When this hormone is not synthesised in proper amount then the sugar level in the blood rises and the persons suffers from a condition called diabetes. Thus, diabetic patients are treated by giving injections of insulin.

Page No. 125

Exercises

1. Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin

Solution

(d) Cytokinin

2. The gap between two neurons is called a
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.

Solution

(b) synapse.

Page No. 126

3. The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.

Solution

(d) all of the above.

4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Solution

Receptors are cells, tissues, and organs which are capable of receiving particular stimuli and initiate impulses to be picked up by sensory nerves. For example, gustatory receptors will detect taste while olfactory receptors will detect smell.
If our gustatory receptors located in tongue do not work properly then we will not be able to perceive the taste of food such as sour, sweet, salty or bitter.

5. Draw the structure of a neuron and explain its function.

Solution

Structure of Neuron:

A neurons consists of three parts;

(i) Cell body: It is a typical animal cell which contains cytoplasm and a nucleus.

(ii) Dendrites: A number of long and thin fibres comes out from the cell body of the neurons, they are nerve fibre. The shorter fibres on the cell body of neurons are called dendrites.

(iii) Axon: The longest fibre on the cell body of neurons is called axon. It has an insulating and protective sheath (or cover) of myelin around it.

Structure of Neuron

Function of Neuron:

Dendrites of a neuron collect information from the receptors and pass it to the cell body in the form of electrical impulse. From the cell body, impulse passes along the axon to its end. At end of the axon, the electrical impulse results in the release of certain chemicals (neurotransmitters). These chemicals cross the gap (synapse) between the endings of the axon and dendrites of the next neuron and start a similar electric impulse in the dendrites. Thus, information received, travels along the neurons of a nerve to the effector muscles or gland.

6. How does phototropism occur in plants?

Solution

The response of plant towards the environmental triggers, light which change the directions that plant parts grow in is called phototropism.
phototropism

When light falls from one direction on the shoot, the growth hormone auxin diffuses towards the shady side of the shoot. This increased concentration of auxin stimulates the cells to grow longer on the shaded side of the shoot. This enhanced growth on one side cause bending of shoot towards light.

7. Which signals will get disrupted in case of a spinal cord injury?

Solution

Reflex actions are involuntary actions and controlled by the spinal cord thus, gets disrupted in case of spinal cord injury.

8. How does chemical coordination occur in plants?

Solution

Chemical coordination in plants occur through phytohormones. These are the chemical compounds which are produced in the cells of the tips of main stem and branches. These hormones are diffused from the originating cells to the neighbouring cells through diffusion. They are responsible for cell elongation, cell multiplication, opening of flowers etc. The important plant hormones are auxins, cytokinins, gibberellins, abscisic acid and ethylene.

9. What is the need for a system of control and coordination in an organism?

Solution

An organism needs a system of control and coordination for its healthy survival. Coordination is needed for all human activities like, thinking and behaviour. Our nervous system gets information from surroundings and processes it and then respond according to it. The endocrine system (hormonal system) helps in integrating various metabolic activities like reproduction, development, all reflex actions (cope up with various give up situations). The hormonal system in plants helps in process of photosynthesis; they need carbon dioxide, water and sunlight.

10. How are involuntary actions and reflex actions different from each other?

Solution

Involuntary Actions Reflex Actions
These actions which is not controlled by our will. These are sudden action in response to something in the environment.
It is controlled by brain. It is controlled by spinal cord.
They are connected with the functioning of internal body part. They are connected with response of stimuli.
Example: heart beat, breathing process; etc. Example: stepping out in bright light, changes in size of pupil of eyes.

11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Solution

Nervous systemHormonal system
Made up of neurons (nerve cell).Made of secretory cells (glands).
Messages transmitted in the form of electrical impulses.Messages transmitted in the form of chemicals called hormones.
Messages transmitted along nerve fibre.Messages transmitted along blood stream.
 Effect of message usually lasts for a very short while.Effect of message usually lasts longer.
Messages travel very quickly.Messages travel more slowly.

12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?

Solution

Movement in sensitive plants Movements in legs
The leaves of sensitive plants can sense external stimuli. No special organs in leg for such action.
Plant cells do not have specialised movements. Animal cells have specialised protein which help muscles to contract.
There is no special tissue in plants for the conduction of information. It is controlled by the brain and spinal cord.
The cells change their shape by changing the amount of water in them. There is no effect of the amount of water on the movement of muscles.


Post a Comment (0)
Previous Post Next Post