CBSE Class 10 Science Important Questions Chapter 7 Control and Coordination Part 2

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2 Marks Questions

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

Ans.

Actions and Reflex Actions
Actions and reflex actions

Involuntary action

Reflex action

The action which we cannot do by thinking about them is called involuntary action.

An action or response which in immediate and that does not need processing by the brain is called reflex action.

Involuntary actions are controlled by brain

Reflex actions are controlled by spinal cord.

2. Why is the use of iodised salt advisable?

Ans. Iodine is required by the thyroid gland to make thyroxine hormone. Iodised salt provides iodine needed by thyroid gland to make sufficient thyroxin for our body. The use of iodised salt prevents risk of goiter.

3. Name the centre of the brain that controls

(i) Swallowing

(ii) Hearing

Ans.(i) Medulla oblongata in hind brain.

(ii) Swallowing cerebrum in fore brain – Hearing

4. Represent schematically the path of a reflex action.

Ans.

Represent schematically

Represent Schematically

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

Ans. Insulin hormone which is secreted by pancreas regulates the levels of sugar in the blood. In diabetic patients it is not secreted in required amount therefore blood sugar level rises and causes various harmful effects. So, to prevent these effects some patients of diabetes are treated by giving injections of insulin.

6. Which signal will get disrupted in case of a spinal cord injury?

Ans. (i) It disturbed all the involuntary actions.

(ii) Reflex actions will be disrupted because reflexes are located in the spinal cord. Therefore, the quick response required to safe guard the body will not take place.

7. How does a touch – me – not plant respond on touching? What is this movement called?

Ans. Touch – me – not plant folds its leaflets on touching. This type of movement is called Growth independent movement.

8. What are phytohormones? Name them.

Ans. Phytohormones are special chemical compounds released by different parts of plant. They help to co – ordinate growth, development and responses to the environment. They are synthesized at site away from where they act and simple diffuse to the area of action. These are –

a) Auxin

b) Gibberlins

c) Cytokinin

d) Abscisic acid

e) Ethylene.

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

Ans. A reflex action is one which we perform automatically. The sensory and motor nerves meet at a point in the spinal cord on their way to the brain. Thus the information through sensory nerves goes to the brain, where thinking process occurs. But if the reflex action is instant where thinking in not involved then the brain has no role.

10. How is control and co – ordination between environment and plants brought about?

Ans. Plants do not have a nervous system for control & co – ordination like animals but do give response to external stimuli like touch, light and chemicals etc. plants responses are mainly of two types – Growth dependent and growth in dependent response.

Growth in dependent Responses are because of change in the amount of water. Growth dependent responses are due to cell divisions.

11. Give two examples of function in plants that are regulated by light

Ans. 1) Breaking of dormancy (seed germination)

2) Flowering

12. What is co – ordination? Give an example.

Ans. The working together of the various systems in a body to adjust the vital activities of life is called co – ordination. Forex – the nervous system receives information form the surroundings, then processes and interprets it and finally responds accordingly. The endocrine system helps in control and co – ordination.

13. How endocrine glands do helps in maintaining feedback control?

Ans. The timing and amount of hormones released are regulated by feedback mechanism. For example, glucose level in the blood is maintained constant (0.1%). The blood glucose levels may be maintained constantly by either of the following feedback mechanism.

a) High glucose level in the blood induces the pancreatic cells to produce insulin which converts glucose to glycogen.

b) Less glucose level in the blood do not induce the pancreateic cells to produce insulin so that less conversion of glucose to glycogen may occur.

14. Which types of glands in human body secrete hormones? State any one location for them.

Ans. There are three types of glands which secrete hormone in human body-

a) Exocrine gland – these are duct glands which do not secrete their secretion into the blood .For ex – salivary gland. it secretes salivary amylase which digest starch.

b) Endocrine – gland – These are ductless gland, and they pour their secretion in blood .For ex – Pituitary gland. It is master gland, controls most of the activities.

c) Heterocrine gland – which act as both endocrine and exocrine type of glands. For Ex Pancreas – Endocrine part produces hormone insulin and glycogen and exocrine part produce digestive enzymes..

15. What is the result of hypothyroidism in children called?

Ans. Hypothyroidism in children called exophthalmic goiter. It causes bulging of eyes, Increases blood pressure and heart beat.

16. How following is affected in plants by various hormones?

Ans. Hormones like Auxins, cytokinin promotes female flowers. Whereas Gibberellins promote male flowers. Ethylene promote flowering in some plants like pineapple Phytohormones and duration of light also induce flowering in long day plants and short day plants.

17. Name the fluid filled between the menings of the brain. What are its functions?

Ans. Cerebrospinal fluid. It protects the brain form mechanical shocks.

18. Name any two heterocrine glands and mention their function.

Ans.

Two Heterocrine Glands and Mention
Two heterocrine glands and mention

Heterocrine gland

Endocrine function

Exocrine function

Pancreas

Produce insulin & glucagon

Produce digestive enzymes

Ovaries

Produce estrogen and progesterone hormone

Produce female gametes

19. What is the response of stem towards light & gravity?

Ans. Stem show positive response towards light and negative response toward gravity.

20. Name two activities which are regulated by plant pigments.

Ans. 1) some specialized pigments, phytochromes are responsible of the response to photoperiodic stimulus.

2) The control and co – ordination in plants with its environment is regulated by phytohormoens & phytochromes together.

21. How do we detect the smell of an agarbatti (incense stick)?

Ans. Smell of agarbatti is detected by olfactory receptors in the temporal lobe of fore-brain. It is first received by olfactory receptors in our nose.

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

Ans. Reflex arcs are formed in the spinal cord itself although the information also goes on to brain where the encounter remains the memory and make us aware of our action.

23. What are plant hormones?

Ans. They are chemical which help to coordinate growth, development, flowering and response to the environment in plants.

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

Ans. Difference between movement of leaves of sensitive plants and movement of shoot towards light:

Sensitive Plants and Movement of Shoot
Sensitive plants and movement of shoot

Movement of Leaves sensitive plant

Movement of shoot towards light

(i) Growth is not involved.

(ii) Movement is away from the source of stimulus (touch).

(i) Growth is involved.

(ii) Movement is towards the source of stimulus (light).

25. How does chemical coordination take place in animals?

Ans. The chemical coordination is maintained by hormones. These are secreted by endocrine glands. These hormones are poured into blood through which they reach the target tissue or organ to act.

26. Why is the use of iodised salt advisable?

Ans. Iodine is necessary for the thyroid gland to make thyroxin hormone. In case, iodine is absent in our diet, there is a possibility of Goitre. Iodised common salt contains proper content of iodine. To avoid deficiency of iodine, iodised salt is recommended.

27. Jive one example of plant part.

a. Which is positively hydrotropic as well as positively geotropic?

b. Which is positively phototropic but negatively geotropic?

Ans. a. roots

b. stem

28. The neck of a person appears to be swollen.

a. Name the disease this person suffering from.

b. Name the mineral whose deficiency in the diet causes this disease. Ans. a. Goiter

b. Iodine

29. Taking the example of heart beat, justify the antagonistic action of the sympathetic and the Sympathetic and the parasympathetic nerves.

Ans. Sympathetic system increases contraction and rhythm and parasympathetic system decreases contraction and rhythm with respect to heart beat

30. Why is abscise acid known as stress hormone in plants?

Ans. Abscise acid in a plant hormone which inhibits growth. Its effects include wilting of leaves.

31. Name the part of neuron

(a) Where information is acquired.

(b) Through which information travels as an electrical impulse.

Ans. a. Dendrite

b. Axon

32. Why do leaves drop off seasonally?

Ans. The leaves drop off seasonally as they stop producing axing, which normally prevents the formation of abscission zone that cuts off nutrients and water supply to leaves.

Therefore, they release their secretions into the blood.

33. A person suffered a head injury, due to which he faces breathing problem. No problem was detected with his respiratory system. What could be the cause of this problem?

Ans. As the problem is caused due to head injury, it could be related to “Pons” a part of Hind brain responsible for regulation of respiration.

34. In a family of normal sized members, there are two exceptions, one member is dwarf and one is tall like “Khali”. What could be the cause of it?

Ans. In case of dwarfs, there is a deficiency of growth hormone from Pituitary gland and in case of giants excess or growth hormone is produced during childhood.

35. Why do you blink your eyes as bright light is focused on you?

Ans. We blink in order to protect the eye from bright light which otherwise would damage the retina.

36. There is a polled plant in your drawing room, after few days you note that plant has bent to one side. What could be the reason? How has this movement been coordinated?

Ans. The plant has bent to one side due to phototropic movement of the stem. This movement is due to unequal growth of the stem on both sides. This growth is initiated by the hormone auxin.

37. A leaf shaped gland is present above the intestine. The secretion of this gland regulates the metabolism of sugar in blood. Name the secretion and gland.

Ans. The name of the gland is pancreas. The secretion is Insulin from special cells in it.

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