CBSE Class 10 Science Important Questions Chapter 7 Control and Coordination Part 4

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17. What are the different kinds of neurons?

Ans. Kinds of neurons –

a) Sensory neurons – convey impulses from receptors to the main nervous system.

b) Motor neurons – carry impulses from the main nervous system to an effector.

c) Connecting (Relay) neurons – connect sensory and motor centres.

18. How does chemical co-ordination takes place in animals. Mention their function.

Ans. The chemical co – ordination in animals takes place through hormonal system called endocrine system. Animal hormones are chemical messengers which are directly poured into the blood by the endocrine glands. Thus, a hormone reaches to the cells. The cells have special molecules on their surface to detect these chemical compounds and recognize the information a particular hormone carrying. There the cells act accordingly. The chemical co – ordination is fast as hormones diffuse readily around the cells.

19. You have touched a hot object. Represent diagrammatically the path that leads to a response, i.e. quickly pulling back the hand.

Ans.

Represent diagrammatically

Represent Diagrammatically

Represent diagrammatically

20. Nervous and hormonal system together performs the functions of control and co – ordination in human beings. Justify the statement.

Ans. A number of interactions between the environment and the animal are a result of combined action of both neurons and endocrine system for which specialized tissues are used to provide Control and co – ordinations activities.

Control and co – ordinations activities

Control and Co – Ordinations Activities

Control and co – ordinations activities

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

Ans. Difference between reflex action and walking:

Action and Walking
Action and walking

Reflex action

Walking

(a) Take place without thought.

(b) Controlled by spinal cord.

(c) It is involuntary action

(a) Takes place after thought.

(b) Controlled by cerebellum.

(c) It is a voluntary action.

22. What happens at the synapse between two neurons?

Ans. At synapse, the electrical impulse generated a dendrite of a neuron is passed on to dendrite of another neuron in form of chemical impulses. The chemical present at synapse is called neurotransmier.

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

Ans. When tendrils come in contact of any support, the part of the tendril in contact does not grow as rapidly as the part away from the object due to auxin secreted moves away from the object in contact. This rapid growth on one side causes tendril to circle around the object.

24. Design an experiment to demonstrate hydrotropism.

Ans. Take a tin box with hole at bottom. Fill it with moist saw dust. Sow some gram seeds in it. Keep the tin box in tilted position .When seeds start germinating, water the saw dust only in lower side of the tin box. You will observe that the radicle move towards the wet saw dust. This shows that root is positively hydrotropic.

Demonstrate hydrotropism

Demonstrate Hydrotropism

Demonstrate hydrotropism

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

Ans. when adrenaline reaches the various target organ through blood. All these organs respond together to enable our body to deal with situation like running away from scary situation. When adrenaline reaches the heart, it beats faster to supply more oxygen to our muscles. The small arteries around digestive system and skins contracts to divert the blood towards muscles. All these response enable our body to deal with situation.

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

Ans. Diabetes is caused due to non or less secretion of hormone insulin by pancreas. In such person, the blood sugar level is high. Insulin converts extra sugar present in blood into glycogen. Patients suffering from diabetes are given insulin injection to control their blood sugar level.

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

Ans. Receptors detect all the information from our environment. These receptors are located in our sense organs. In case any of the receptors do not work properly we will not be able to perceive that particular information.

28. How phototropism does occur in plants?

Ans. Movement of shoot towards light is called phototropism. This movement is caused due to more growth of cells towards the shaded side of the shoot as compared to the side of shoot towards light. More growth of cells is due to secretion of auxin towards the shaded side.

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

Ans. (i) Reflex action

(ii) Impulses from various body parts will not conducted to brain.

(iii) Message from brain will not be conducted to various organs.

30. How does chemical coordination occurs in plants?

Ans. Chemical coordination in plants is maintained by plant hormones also known as phytohormones. Some of these hormones promote growth while some inhibit it. Some hormones include auxin, Gibberellins, Cytokinin etc.

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

Ans. An organism has different organs which perform various factions. The survival of an organism depends on integrated and coordinated functions of these organs. Nervous and endocrine system of an organism makes them work together like parts of one machine to accomplish homeostasis or coordination.

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

Ans. Difference between involuntary and reflex actions is as follows:

Involuntary and Reflex Actions
Involuntary and reflex actions

Involuntary actions

Reflex actions

It is a set muscles movement over which we do not have control. Such actions are controlled by brain. For example- contraction of muscle of our digestive tract, beating of heart etc.

It is rapid, spontaneous and involuntary activity that is produced in response to a stimulus. It is controlled by spinal cord. Example-removal of hand with jerk when someone touches a hot object.

33. Compare and contrast nervous system and hormonal control and coordination in animals.

Ans. Difference between nervous control and hormonal control:

Hormonal Control and Coordination
Hormonal control and coordination

Nervous control

Hormonal control

(i) Consists of nerve impulses conducted by neurons from one organ to another organ.

(ii) Nervous impulses produce rapid short lasting responses.

(iii) Nervous impulses are not specific in their action.

(i) It consists endocrine system which scretes chemical messenger’s hormones secreted directly in blood.

(ii) Hormones produce longer lasting responses.

(iii) Action of hormones is highly specific.

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

Ans. Difference between movement in a sensitive plant and movement in our legs:

Sensitive Plant and Movement in Our Legs
Sensitive plant and movement in our legs

Movement in sensitive plant

Movement in our legs

(i) There is no specialized tissue in plants for conduction of information.

(ii) Plant cells change shape by changing the amount of water in them.

(iii) Plant cells do not have specialized proteins.

(i) There is specialized tissue in animals for conduction of information and muscle cells to help in movement.

(ii) Muscle cells contract relax to effect movement.

(iii) Muscle cells have specialized protein which help muscles to contract or relax.

35. On touching a hot plate, you suddenly withdraw your hand. Which category of neurons became active first and which one next?

Ans. On touching a hot plate, first the sensory neurons are activated, which take the information to the brain or the spinal cord. Next, the motor neurons become active and bring the impulses from the brain to the muscles. In receiving these impulses, the muscles contract, and the hand is immediately removed from the hot plate.

36. How does the plant shoot bends, when the plant is placed in a room having only one open window?

Ans. When the plant is placed in such a room that has only one open window, the shoot of the plant bends towards the direction of light. Plant hormone axing is formed that diffuses towards the shady side of the shoot and stimulates the cells to live longer on the side of the shoot which is away from light. In this way the shoot bends towards the light.

37. Give a reason to explain why

(a) Adrenaline helps in dealing emergency situations?

(b) Secretions of growth hormone should be specific in the human body?

Ans. a. Adrenaline increases the heart beat and breathing rate which results in the supply of more oxygen to muscles. It reduces the blood to the digestive system and skin, as a result the blood is further diverted to skeletal muscles. All these responses together prepare the body to deal with the emergency situations.

b. If growth hormones is secreted in excess during childhood then it leads to gigantism while the less secretion of this hormone during childhood causes dwarfism.

38. A man becomes unconscious due to head injury. A pin is pricked on his foot, he withdraws his foot. Why? Explain.

Ans. It is reflex action. Stimulus is perceived by receptor (skin). Sensory nerve sends the sensation from receptor to the spinal cord. Then spinal cord sends the message through motor nerves to the effectors. Effectors i.e. muscles help in withdrawing his foot.

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