Bihar Board Class 10 Science Solutions Chapter 7 Control and Coordination

BSEB Bihar Board Class 10 Science Solutions Chapter 7 Control and Coordination Textbook Questions and Answers.

Bihar Board Class 10 Science Solutions Chapter 7 Control and Coordination

Bihar Board Class 10 Science Chapter 7 Control and Coordination InText Questions and Answers

In-text Questions (Page 119)

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

Question 2.
What happens at the synapse between two neurons?
Answer:
Nerve impulses are carried from one neuron to another neuron which lie end to end but are not connected. The small gap between the neurons is called as synapse. It is filled with a chemical (neurotransmitter substance). The electrical impulse from the axon of one neuron sets off the release of these chemicals into the synapse. The chemicals released transmit the impulse to the dendrite of the next neuron to create an electrical impulse in it. This presence of synapse between the junctions of axon endings and dendrites helps in transmission of impulse in one direction.

Question 3.
Which part of the brain maintains posture and equilibrium of the body?
Answer:
Cerebellum region of hind brain.

Question 4.
How do we detect the smell of an agarbatti (incense stick)?
Answer:
Olfactory receptors present in ours nose detect smell and transmit the information to forebrain which interprets the message.

Question 5.
What is the role of the brain in reflex action?
Answer:
Reflexes are of two types: Spinal reflexes and cerebral reflexes. Spinal reflexes are controlled by spinal cord but the message is also sent to brain for interpretation of the action. For example, removing hands on touching a hot object. Cerebral reflexes are controlled by the brain. For example, production of saliva on sight of spicy food.

In-text Questions (Page 122)

Question 1.
What are plant hormones?
Answer:
Chemical substances which help in the proper growth and development of the plants and also enable them to respond to the environment are called plant hormones. For example, auxin, cytokinin, etc.

Question 2.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Answer:
The leaves of the sensitive plants like ‘Touch-me-not’ lose turgor pressure in cells and cause drooping of its leaves/leaflets. The movement of the shoot towards light occurs due to more growth of shoot on the part away from light as auxin concentration gets increased at this part.

Question 3.
Give an example of a plant hormone that promotes growth.
Answer:
Auxin.

Question 4.
How do auxins promote the growth of a tendril around a support?
Answer:
The concentration of auxin gets increased on the free side of the tendril as compared to the part in contact with the support. So, more growth occurs on the free side and enables the tendril to coil around a support.

Question 5.
Design an experiment to demonstrate hydrotropism.
Answer:
Hydrotropism is a plant growth in which the direction of growth is determined by the stimulus or gradient in water concentration.

Take a sieve, put some sawdust in it and make it moist by adding some water. Now place a few germinating seeds on moist sawdust. After some days, the radicles will be seen growing downwards under the influence of gravity. But after a further few days, it can be observed that the radicles bend back and enter the moist sawdust due to the hydrotropic response of the roots.

In-text Questions (Page 125)

Question 1.
How does chemical coordination take place in animals?
Answer:
Chemical coordination is achieved by the hormones secreted by the endocrine glands (ductless glands) in the animals. Hormones are secreted in very small amounts, secreted directly into the blood and act only at the target organ. They help in the coordination of various activities of the body. For example, stress hormone called adrenaline is secreted to respond during emergency situations.

Question 2.
Why is the use of iodised salt advisable?
Answer:
Iodised salt is a source of iodine which is a constituent of hormone called thyroxine. Due to reduced synthesis of iodine the fat, carbohydrate and protein metabolism gets disturbed which leads to a disease called goitre. So, in order to avoid goitre, the use of iodised salt is advisable.

Question 3.
How does our body respond when adrenaline is secreted into the blood?
Answer:
Adrenaline is secreted in higher amounts in our body during stress or emergency situations to respond to the situation in an effective manner. It increases the rate of heart beat, breathing rate and blood pressure which causes release of more glucose in the blood to provide energy. In this way adrenaline helps the organism to overcome the stressful situation. Hence, its also called as stress hormone or emergency hormone.

Question 4.
Why are some patients of diabetes treated by giving injections of insulin?
Answer:
Sometimes due to insufficient production of insulin by the pancreas, the level of glucose in the blood rises. The excess glucose gets excreted by the person in urine and leads to the disorder called diabetes. So, in order to supplement the requirement of insulin, the patients are treated by giving insulin injections.

Bihar Board Class 10 Science Chapter 7 Control and Coordination Textbook Questions and Answers

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

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

Question 3.
The brain is responsible for
(a) thinking
(b) regulating the heartbeat
(c) balancing the body
(d) all of the above
Answer:
(d) all of the above

Question 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 present in our sense organs like nose, ear, tongue, skin, etc. They help in receiving the stimulus and transmitting it through the sensory nerves to the central nervous system for generating a response.

If receptors do not work properly then we will not be able to perceive the information and this can lead to many problems. For example, if the receptors present on the skin do not work then we will not be able to sense the objects properly. Similarly, if receptors of the nose do not work properly then we will not be able to sense the smell properly.

Question 5.
Draw the structure of a neuron and explain its function.
Answer:
The basic structural and functional unit of the nervous system is called as a nerve cell or neuron. A neuron has three parts-Cell body, dendrites and axon.

The dendrites help to acquire the information from the receptors on the sense organs and transmit it in form of electrical impulse to the axon through the cell body of the neuron. At the end of the axon, the electrical impulse leads to the release of chemicals at the synapse which starts a similar electrical impulse in the next neuron on being received by its dendrites. This enables transmission of nerve impulse in one direction from one neuron to another till it reaches the target organ, muscles, gland or brain.

Question 6.
How does phototropism occur in plants?
Answer:
The directional movement of a plant or its part in response to unidirectional exposure to light is called phototropism. The site of perception of light is the shoot/ root apex where auxin is synthesised. The shoot apex bends towards light while the root apex bends away from light. Auxin is a shade loving hormone which is uniformly spread in the stem. But, due to unidirectional exposure to light the auxin moves away from light and moves towards the shaded part of the stem. More amount of auxin on the shaded side of the plant causes more growth on the dark (shaded) side of stem, thereby bending the stem towards the source of light.

But in the case of the root an increase in the auxin on the side away from light causes a slower growth on that side. So, the root bends away from light.
Thus, the effect of auxin on growth of stem is opposite to its effect on the growth of root.

Question 7.
Which signals will get disrupted in case of a spinal cord injury?
Answer:
Reflex actions will get disrupted along with the involuntary actions of the nervous system.

Question 8.
How does chemical coordination occur in plants?
Answer:
Plant hormones (phytohormones) help in chemical coordination in the plants. These are of two types: Growth promoters like auxin, gibberelin, cytokinin; and growth inhibitors like abscissic acid and ethylene. Auxins cause apical growth, cytokinin causes cell division, and gibberelin causes growth of stem. Abscissic acid causes closing of stomata and wilting of leaves, ethylene causes fruit ripening.

Question 9.
What is the need for a system of control and coordination in an organism?
Answer:
Multicellular organisms have different tissues and organs which are specialised for a particular function. There is a need of these organs to act in a coordinated manner for the proper functioning of the body. So, the nervous system and the endocrine system are needed for effective control and coordination in an organism.

Question 10.
How are involuntary actions and reflex actions different from each other?
Answer:
Involuntary actions:

• The actions of the organism which are not in control of its will are called as involuntary actions.
• It is controlled by the hindbrain region of the brain.
• They are comparatively slower than the reflex actions.
• Stimulus in these actions is usually internal.
• For example, movements in muscular wall of oesophagus, beating movement of heart muscles.

Reflex actions:

• An automatic, immediate, involuntary response of an organism.
• It is controlled by the spinal cord.
• It is a very fast response.
• Stimulus in these responses is generally external.
• For example, knee jerk movement or moving the hand away on touching a hot object.

Question 11.
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Answer:
Nervous Control:

• Information is transmitted in the form of electrochemical impulse/reaction.
• Transmission of impulse is very fast.
• The impulse through nerve is not specific.
• It produces short lasting responses.

Hormonal Control:

• Information is carried in the form of chemicals called hormones through the bloodstream.
• Transmission of impulse is slower.
• The action of hormones on the target organ is highly specific.
• It produces responses which are longer lasting.

Question 12.
What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
Answer:
Movement in Sensitive Plant:

1. The response is produced due to the change in amount of water in the plant cells.
2. No nerve or specialised tissue involved in the conduction of information.
3. It occurs due to plant hormones and not due to specialised proteins.

Movement in Legs:

1. The response occurs due to contraction and relaxation of the muscle cells.
2. Nerves are involved along with muscle cells in conduction of information.
3. It occurs due to specialised proteins which help in contraction and relaxation of muscles.

Bihar Board Class 10 Science Chapter 7 Control and Coordination Textbook Activities

Activity 7.1 (Textbook Page 115)

Sugar has a sweet taste. No difference in taste will be observed if we eat sugar while pressing our nose between thumb and index finger, because the smell of sugar does not influence its taste. The smell of food perceived by the receptors of smell (olfactoreceptors) helps to stimulate the receptors of taste (gustatoreceptors). We will not be able to fully appreciate the taste of the food we are eating if we press our nose between thumb and index finger while eating because we won’t be able to smell the food.

Activity 7.2 (Textbook Page 121)

Yes, the old parts of the shoot and root changed direction. When the flask is placed in the cardboard which is open from one side which faces light coming from a window, the shoots of freshly germinated seeds show growth by bending towards light and roots show growth by bending away from light.

But, when the flask is turned so that the shoots are away from light and the roots towards light, we observe after few days that the shoots again grow by bending towards light and the roots grow by bending away from light. This experiment shows that the shoots of plants respond by showing growth movement towards light (i.e, positive phototropism) and roots of plants respond by showing growth movement away from light (i.e., negative phototropism)

Activity 7.3 (Textbook Page 123)