NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination
Get free NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination that provide reliable answers to all the questions from the NCERT textbook. These solutions are also important for SEBA board or any state board that follows the NCERT Text books. These solutions help students understand important topics such as the human nervous system, neurons, reflex actions, hormones, the endocrine system, and coordination in plants. All the answers are written in simple English to help you build a strong understanding of the chapter and score better in your upcoming HSLC examinations. Whether you are studying the chapter for the first time or revising before your exams, these NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination will help you build strong concepts and answer questions with confidence.
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NCERT Solutions for Class 10 Science Chapter 7: Page 119
1. What is the difference between a reflex action and walking?
Answer:
| Reflex Action | Walking |
|---|---|
| Reflex action is a quick and automatic response to a stimulus. | Walking is a voluntary activity performed according to our will. |
| It does not require conscious thinking. | It is a conscious action that requires thinking and decision-making. |
| It is an involuntary action. | It is a voluntary action. |
| It is controlled by the spinal cord. | It is controlled and coordinated by the brain. |
| It occurs very quickly. | It takes longer than a reflex action. |
2. What happens at the synapse between two neurons?
Answer:
A synapse is the small gap between two neurons. When an electrical impulse reaches the end of the axon of the first neuron, it triggers the release of chemical messengers (neurotransmitters). These chemicals cross the synapse and stimulate the dendrite of the next neuron. There, they generate a new electrical impulse. In this way, the nerve impulse is transmitted from one neuron to another.
3. Which part of the brain maintains the posture and equilibrium of the body?
Answer:
The cerebellum is responsible for controlling the posture, balance, and equilibrium of the body.
4. How do we detect the smell of an agarbatti (incense stick)?
Answer:
The smell of an agarbatti is detected by olfactory receptors present in the nose. When the scent enters the nose, these receptors convert it into electrical signals. These signals are carried by sensory nerves to the forebrain, where they are interpreted. The brain then identifies it as the smell of the incense stick.
5. What is the role of the brain in reflex action?
Answer:
Reflex actions are mainly controlled by the spinal cord, through a reflex arc. The spinal cord quickly processes the incoming stimulus and sends an immediate response. The brain does not take part in producing the reflex action, so there is no delay due to thinking.
However, the information about the reflex action also reaches the brain. The brain becomes aware of the event and stores it as a memory, which may help in future responses.
NCERT Solutions for Class 10 Science Chapter 7: Page Number: 122
Q1. What are plant hormones?
Answer:
Plant hormones (or phytohormones) are chemical substances produced in plants that control and coordinate various functions. They regulate growth, development, and responses to environmental conditions. These hormones are synthesised in one part of the plant and act on another part.
The main types of plant hormones are auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
Q2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light ?
Answer:
| Movement of leaves of sensitive plant | Movement of shoot towards light |
|---|---|
| It is a nastic movement. | It is a tropic movement (phototropism). |
| It does not depend on the direction of the stimulus. | It depends on the direction of light stimulus. |
| The stimulus is touch. | The stimulus is light. |
| It occurs due to the sudden loss of water from the cells at the base of the leaf. | It occurs due to unequal growth on two sides of the shoot. |
| It is not a growth-related movement. | It is a growth-related movement. |
| It happens quickly. | It happens slowly. |
Q3. Give an example of a plant hormone that promotes growth.
Answer: Auxin.
Q4. How do auxins promote the growth of a tendril around a support ?
Answer:
When a tendril touches a support, auxin moves to the side away from the support. Since auxin promotes cell growth. So, this side grows faster than the side touching the support. This unequal growth makes the tendril bend and coil around the support.
Q5. Design an experiment to demonstrate hydrotropism.
Answer:
Procedure:
Take two similar seedlings and plant them in separate troughs filled with soil. In trough A, water the soil uniformly on both sides. In trough B, place a porous pot filled with water on one side and do not water the soil directly.
Leave both setups for a few days.
Observation:
In trough A, the roots grow straight. In trough B, the roots bend towards the porous pot containing water.
Conclusion:
This experiment proves that plant roots grow in the direction of water. This growth response towards water is called hydrotropism.
NCERT Solutions for Class 10 Science Chapter 7: Page Number: 125
Q1: How does chemical coordination take place in animals?
Answer:
Chemical coordination takes place in animals with the help of chemical messengers called hormones, which are secreted by the endocrine glands. Endocrine glands are ductless glands that secrete hormones directly into the blood. Blood carries these hormones to specific target cells. These target cells have special receptors that detect the hormones and carries out the required function, such as regulate growth, development, or maintaining body balance. For example, the pancreas releases insulin and glucagon to regulate blood sugar levels.
Q2: Why is the use of iodised salt advisable?
Answer:
The use of iodised salt is advisable because iodine is necessary for the thyroid gland to produce thyroxine hormone.
Thyroxin regulates carbohydrate, protein and fat metabolism in the body to provide the best balance for growth. If iodine is deficient in our diet, the thyroid gland cannot produce enough thyroxine. Therefore, we might suffer from goitre. One of the symptoms of goitre is a swollen neck. Therefore, using iodised salt helps prevent iodine deficiency and goitre.
Q3. How does our body respond when adrenaline is secreted into the blood ?
Answer:
Adrenaline is secreted into the blood during situations of fear, stress, or danger; it prepares the body for a fight-or-flight response. It is also known as the “emergency hormone”.
When adrenaline is secreted into the blood, the following changes happen in the body:
- Adrenaline increases the heartbeat to supply more oxygen to the muscles.
- It increases breathing rate due to the contraction of the diaphragm and rib muscles.
- It increases blood supply to skeletal muscles by reducing blood flow to the digestive system and skin.
Q4: Why are some patients of diabetes treated by giving injections of insulin?
Answer:
The pancreas produces the insulin hormone. It regulates blood sugar levels by converting excess glucose into glycogen in the liver. When the body is unable to produce enough insulin, the blood sugar level rises. This condition is called diabetes. Diabetes can cause several harmful effects. So, to maintain insulin and blood glucose levels, doctors advise insulin injections to diabetic patients. These injections help bring the blood sugar level back to normal.
NCERT Solutions for Class 10 Science Chapter 7 Textbook Chapter End Questions
Q1. Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin
Answer: (d) Cytokinin
Q2. The gap between two neurons is called a
(a) dendrite
(b) synapse
(c) axon
(d) impulse
Answer: (b) Synapse
Q3. The brain is responsible for
(a) thinking
(b) regulating the heart beat
(c) balancing the body
(d) all of the above
Answer: (b) 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?
Answer:
Receptors are special cells found in our sense organs, such as the eyes, ears, nose, tongue, and skin. Their main function is to detect changes in the surroundings (stimuli) and convert them into nerve impulses. These impulses are sent to the brain or spinal cord, which then directs appropriate body parts to produce a response.
When receptors do not work properly, information from the environment cannot be detected, and our body cannot respond accordingly. This can lead to serious accidents or harm. For example, if the receptors in the skin are damaged, a person may not feel heat and may get burned on touching a hot object.
5. Draw the structure of a neuron and explain its function.
Answer:
A nerve cell or neuron is the structural and functional unit of the nervous system. It has three main parts: dendrites, cell body and axon. Its functions are:
- Dendrites receive nerve impulses and carry them to the cell body.
- Cell body processes the incoming impulses and transmit to the axon. It also maintains cell growth.
- Axon carries nerve impulses away from the cell body to another neuron, muscle, or gland.
6. How does phototropism occur in plants?
Answer:
Phototropism is the bending of a shoot towards light.
Phototropism occurs due to the action of the auxin hormone. When light falls on one side of the shoot, auxin moves towards the shaded side. This causes the cells on the shaded side to grow faster than the cells on the lighted side. As a result, the shoot bends towards the light.
7. Which signals will get disrupted in case of a spinal cord injury?
Ans:
The spinal cord acts as a bridge between the body and the brain. If it is damaged, the signals from receptors to the brain and from the brain to muscles cannot be properly transmitted. As a result, reflex actions get disrupted, since reflexes are controlled by the spinal cord itself. Also, involuntary actions get disrupted. This means the body loses its ability to respond quickly to danger or any change in the surroundings, which can put a person at serious risk.
8. How does chemical coordination occur in plants?
Answer:
Plants do not have a nervous system, so they use chemical substances called plant hormones (phytohormones) for coordination. These chemicals are produced in very small amounts at specific sites like shoot tips or seeds. Then they are transported to other parts where they are needed. Plant hormones regulate growth, development, and responses to environmental stimuli.
Examples of plant hormones are auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Auxin promotes the cells to grow longer, gibberellin helps in the growth of the stem, cytokinin promotes cell division, and abscisic acid inhibits growth and causes wilting of leaves.
9. What is the need for a system of control and coordination in an organism ?
Answer:
An organism needs control and coordination system for the following functions :
- It helps the body to respond to internal and external stimuli and protects it from harmful conditions.
- It also controls and regulates voluntary and involuntary actions.
- It ensures proper communication between different body parts through the nervous system and hormones.
- It manages overall growth of the organism through hormones in both animals and plants.
10. How are involuntary actions and reflex actions different from each other?
Answer:
| Reflex Actions | Involuntary Actions |
|---|---|
| Reflex actions are sudden and automatic responses to stimuli. | Involuntary actions occur automatically without conscious control. |
| They are mainly controlled by the spinal cord. | They are mainly controlled by the brain. |
| They occur very quickly. | They are relatively slower than reflex actions. |
| They protect the body from harm. | They help maintain vital life processes necessary for survival. |
| Ex: Blinking of eyes, withdrawal of hand from a hot object | Ex: Heartbeat, breathing, digestion |
11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Ans.
12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
Ans:
| Movement in a Sensitive Plant | Movement in Our Legs |
|---|---|
| It is an involuntary movement that occurs in response to stimuli such as touch. | It is a voluntary movement that occurs according to our conscious will. |
| It is not controlled by the nervous system. | It is controlled by the brain, spinal cord, and nerves. |
| It takes place due to changes in the amount of water inside plant cells. | It takes place due to the contraction and relaxation of muscles. |
| Information travels without any specialised tissues. | Information travels through the central and peripheral nervous systems. |