NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination

NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination are able to provide accurate and complete solutions for all the questions. This helps them learn from their mistakes and improve their understanding of the material. It will help students prepare for exams better as they will be able to identify areas where they need more revision.

Chapter 7 Class 10 Science NCERT Solutions are a go-to for any students when they face difficulties in their studies. They are also updated on a regular basis, ensuring that students have access to the latest information.

Chapter 7 Control and Coordination Class 10 Science NCERT Solutions

In Text Questions

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

Solution

Reflex Action	Walking
Reflex action is an involuntary action, i.e., it does not take place due to thought or thinking or will.	Walking is a voluntary action, i.e., it takes place due to thought or thinking or will.
It is sudden and fast taking place in response to an action.	It is not spontaneous and conscious effort.
It is controlled by spinal cord.	It is controlled by brain.
The connection between the neurons and spinal cord muscles forms the reflex arc for reflex action to take place.	There is no reflex arc for it.

2. What happens at the synapse between two neurons?

Solution

Synapse is a junction between terminal arborization of one axon and dendrites of adjacent neuron. There is a gap between the two called synaptic cleft. As the electrical impulse reaches the terminal knobs, they release chemicals called neurotransmitter. These chemicals cross the gap and start a similar electrical im- pulse in the dendrite of next neuron.

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

Solution

Cerebellum.

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

Solution

The smell sense is received by the olfactory lobes of the brain, which receive information through the nasal chambers as electrical impulses that are relayed to the brain, which interprets the information.

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

Solution

Thinking centres are located in brain. Brain is the co-ordinating centre. Brain and spinal cord in coordination with each other control all voluntary and involuntary actions.

1. What are plant hormones?

Solution

Plant hormones are chemical substances produced by certain cells in the plant.

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

Solution

Movement of leaves in sensitive plant	Movement of a shoot towards light
It is because of change in the shape of cells due to the amount of water.	It is because elongation of cells due to the auxin (chemical).
It is in response to touch stimulus.	It is in response to light stimulus.
It is a movement without any growth.	It is a movement due to growth.
It is fast/quick response or movement of the plant.	It is very slow response or movement of the plant.

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

Solution

Auxin.

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

Solution

The part of the tendril that is towards light will have less concentration of auxin than the part away from light. The shady part will show growth of cells and increase in size. Therefore, it will grow in circle and coil the support.

5. Design an experiment to demonstrate hydrotropism.

Solution

(i) Take a porous pot and fill it with water.
(ii) Keep a few freshly germinated pea seedlings in dried sand.
(iii) As the water is not available in sand the root growing will bend towards porous pot filled with water.
(iv) You will observe a hydrotropic curvature of the root as it grows towards water.
(v) This bending of root shows the movement as a response towards water.

1. How does chemical coordination take place in animals?

Solution

Chemical coordination takes place in animals by producing hormones.

2. Why is the use of iodised salt advisable?

Solution

Iodine is necessary for the thyroid gland to make thyroxine hormone. Thyroxine regulates carbohydrate, protein and fat metabolism. It is required for growth. In case of deficiency of thyroxine, a disorder called goitre is caused.

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

Solution

Adrenaline is secreted by adrenal gland during emergency. It prepares the body to respond effectively. The following are the actions of adrenaline:
(i) Heart beats faster so as to pump the blood to muscles which need more energy.
(ii) The blood supply to digestive system and skin is reduced due to contraction of muscles around these organs. This helps in diverting blood supply to muscles.
(iii) Breathing becomes fast.

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

Solution

Insulin hormone is secreted by Islets of Langerhans of pancreas. This hormone helps in regulating sugar level in the blood. Its deficiency results in high sugar level and causes many harmful effects.

Exercises

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

Solution

(d) Cytokinin

2. The gap between two neurons is called:
(a) Dendrite
(b) Synapse
(c) Axon
(d) Impulse

Solution

(b) Synapse

3. The brain is responsible for:
(a) Thinking
(b) Regulating the heart beat
(c) Balancing
(d) All of these

Solution

(d) All of these

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

Solution

The function of receptor is to receive the information from the environment through the neurons present in the body (receptor). When the receptors do not work properly or there is an obstruction in above activity then the sense responded by the receptor will not take place. Such as during cold we can not smell certain smells. If such situations arise then we do not respond to the information given by the neurons.

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

Solution

Neuron is the basic unit for information and conduction of impulses. It is the structural and functional unit of the nervous system also. It is responsible for carrying the information from the environment to receptors and from the spinal cord and brain to glands of the body. The information are carried in the form of nerve impulses. It, therefore, connects the different parts of the body, sends and receives information, conducts reflexes, etc. It is just like electric circuit in a building.

6. How does phototropism occur in plants?

Solution

It is an established fact that plants bend towards light when they are exposed to it from one side of long axis. The aerial parts are positively phototropic and the roots and other underground parts bend away from light. These movements are due to inter- action of light and auxins. The unilateral growth causes bending of stem as tip grows more rapidly.

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

Solution

Reflex Actions.

8. How does chemical coordination occur in plants?

Solution

Plants lack well organised control mechanism as in animals. However plants respond to light, touch and gravitational forces. Moreover growth and movements in plants are regulated by external and internal factors.
Plant growth regulators or phytohormones are the chemicals occurring in minute quantities and responsible for regulating metabolism, growth and development.
The important phytohormones are Auxins, Gibberellins, Cytokinins, Ethylene, and Abscisic acid. All growth processes are regulated by one or more phytohormones acting synergistically or antagonistically.

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

Solution

Control and Coordination in the body is of two types i.e. nervous control and hormonal control. Nervous control is rapid. It takes place through electrical signals called nerve impulses. The hormonal control is through chemical messengers called hormones secreted by endocrine (ductless) glands and carried by blood to the target organs.

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

Solution

Involuntary actions	Reflex Actions
Actions that take place by itself but are controlled by the brain are involuntary.	Actions that take place all of a sudden and are controlled by spinal cord.
They do not have any circuit like reflex actions.	The have a circuit called reflex arc.
They take place at all times.	They take place only in presence of a stimulus.
We do not know always about its occurrence, for example, heart beats.	We know about its occurrence, for example, removal of the finger from a flame.

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

Solution

Nervous control	Hormonal control
Such actions are controlled mainly by a network of neurons.	Such action is controlled.
Actions like reflex action are under the nervous control.	Control of blood glucose level in body is under the hormonal control.
Some actions are voluntary while others are involuntary.	All the actions are involuntry.
The cells/tissues/organs are connected with the neurons to CNS or peripheral nervous system.	The cells are supplied with chemicals via the blood.
The actions are fast.	The actions are slow.

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	Movement in leg
Movement in sensitive plant is in response to stimulus- touch.	Movement in leg is in response to our will.
The movement takes place due to change in the shape of cells due to the amount of water.	Movement takes place due to contraction and relaxation of special proteins in muscle cells that changes the shape of cells.
It is not controlled by nervous system as it is absent.	It is controlled by nervous system.