Class 10 Science Cbse Ncert Solutions of Control and Coordination - InText Questions - www.CbseNcertSolution.com

Control and Coordination

Class 10 Science NCERT Solutions of Chapter 7 InText Questions

Control and Coordination - NCERT Solutions of Intext Questions (Page 119)

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

Answer: Reflex action is a process by which we do something without thinking about it or without being in control of our reactions. It is an automatic response to a stimulus which is done by only the spinal cord without the help of brain.

While walking is a process which is done by thinking, or it is performed by the brain under conscious control unlike reflex action.

Question 2: What happens at the synapse between two neurons?

Answer: A very small gap that occurs between the last portion of axon of one neuron and the dendron of another neuron is known as synapse. Synapse acts as one way valve to transmit impulses in one direction only. The uni-directional transfer of impulses occur due to the release of some chemicals in only one side of the neuron, ie, the axon's side. These chemicals cross the synapse and start a simple impulse in the dendrite of next neuron.

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

Answer: Cerebellum, a part of hind brain is responsible for maintaining the posture and equilibrium of the body.

Question 4: How do we detect the smell of an agarbatti (incense sick)?

Answer: The smell of an agarbatti is detected by the forebrain. There are separate areas in our forebrain which are specialised for hearing, smelling, sight, taste, touch etc. Our forebrain has also regions that collect information or impulses from the various receptors. When the smell of an agarbatti reaches us, our forebrain interprets it by putting it together with the information received from other receptors and also with the information already stored in the brain.

Question 5: What is the role of the brain in reflex action?

Answer: Reflex actions are sudden responses to a change in the environment which we do without thinking about it. The nerves from all over the body meet in a bundle in the spinal cord. Thus, reflex arcs are formed in the spinal cord and the information input also goes on to reach the brain. In reflex arc instant and automatic responses possible. The brain is only aware of the signal and the response that has taken place. Here, the brain has no role to play in the creation of the response done by reflex action.

Control and Coordination - NCERT Answers of Intext Questions (Page 122)

Question 1: What are plant hormones?

Answer: Plant hormones are the chemicals released by stimulated cells. This chemical compounds help to coordinate growth, development and responses to the environment. These are synthesised at places away from where they act. The five different types of plant hormones (phytohormones) are Auxins, Gibberellins, Cytokinins, Abscisic acid, and Ethylene.

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

Answer: The movement of leaves of the sensitive plant like Mimosa pudica or "touch-me-not" is either towards nor away from stimulus like touch. While movement of shoot is towards stimulus like light. The movement of leaves of sensitive plants is not directional while the movement of shoot is directional.
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Question 3: Give an example of a plant hormone that promotes growth.

Answer: (i) Auxins help to increase the length of plants.

(ii) Gibberellins help in the growth of stem.

Question 4: How do Auxins promote the growth of a tendril around a support?

Answer: Auxin is synthesised at the shoot tip. The tendrils are sensitive to touch. As these tendrils come in the contact with the support, the auxin diffuses towards the other side away from the support. As it stimulates faster growth of the cells, so, this part grows more rapidly than the other. This causes the tendril to circle around the support and thus climb upwards.

Question 5: Design an experiment to demonstrate hydrotropism.

Answer: Positive hydrotropism can be demonstrated with germinated seedlings, which are allowed to grow on ground (Fig. 7.2). The soil below the roots is separated by a polythene partition. The left side is kept moist but the right side is kept dry. The radicals at first grow in a downward direction due to the effect of gravity (positive geotropism), but after sometime, the roots bend toward the moist soil (positive hydrotropism). This is evidently due to the closeness of the germinating roots to water.

Control and Coordination - NCERT Solutions of Intext Questions (Page 125)

Question 1: How does chemical coordination take place in animals?

Answer: Chemical coordination takes place in animals with the help of some chemical substances called hormones. Hormones are secreted by endocrine glands. The timing and amount of hormone released are regulated by feedback mechanisms.

Question 2: 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. Thyroxine relates carbohydrates, protein and fat metabolism in the body so as to provide the best balance for growth. Iodine is essential for the synthesis of thyroxine. Deficiency of this hormone results in the enlargement of the thyroid gland. This can lead to goitre. Therefore, iodised salt is advised for normal functioning of the thyroid gland.

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

Answer: Adrenaline is a hormone secreted by the adrenal glands in case of any danger, emergency or any kinds of stress. It is secreted directly into the blood and is carried to different parts of the body. It acts on heart also. As a result, the heart beats faster in order to supply more oxygen to the muscles. This also increases the blood pressure. All these responses enable our body to deal with the situation.

Question 4: Why are some patients of diabetes treated by injections of insulin?

Answer: Insulin is a hormone which is produced by the pancreas and helps in regulating blood sugar levels. If insulin is not secreted in proper amounts, the sugar level in the blood increases causing diabetes which has many harmful effects. Therefore, the patients of diabetes are treated by giving injections of insulin.

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