CBSE Class 10 Science HOTs Control And Coordination

Q1 What is cerebrospinal fluid? What is its function?

Ans. The fluid which fills the space between the membranes which cover the brain is called cerebrospinal fluid. It protects the brain from mechanical shocks.

Q2 Taking the example of heart beat, justify the antagonistic action of 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.

Q3 Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the  everse?

Ans. When an electrical signal reaches the axonal end of a neuron it releases a chemical substance. This chemical diffuses towards the dendritic end of next neuron where it generates an electrical impulse. Hence the electrical signal is converted into a chemical signal at the axonal end. Since these chemicals are absent at the dendritic end of the neuron the electrical signal cannot be converted into chemical signal.

Q4 Sameer was studying in his room. Suddenly he smells something burning and sees smoke in the room. He rushes out of the room immediately. Was Sameer’s action voluntary or involuntary? Why?

Ans. Sameer’s action was voluntary because rushing out of the room was under his conscious control. The smoke and smell were perceived by the receptors in the sense organ and signals are sent to the brain. The brain then sent the signals to the effector organs to move out of the room.

Q5 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 auxin 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

Q6: 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.

Q7: Why do leaves drop off seasonally?

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

Q8: Give reason why endocrine glands release their secretions into the blood?

Ans. Endocrine glands are ductless glands and their products have to act at a distant site. Therefore, they release their secretions into the blood.

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

Ans. 

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 1 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. 

5. Why are some patients of diabetes treated by 2 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 6 (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 bodya) 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 7 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 8 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.

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

Ans. Stem show positive response towards light and 9 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:

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 15 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.

Q.1) On touching a hot plate, you suddenly withdraw your hand. Which category of neurons became active first and which one next?

Ans.1) 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.

Q.2) Give one example of plant part.

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

      b. Which is positively phototropic but negatively geotropic.

Ans.2) a. roots b. stem

Q.3) What name is given to the microscopic gap between two adjacent neurons?

Ans.3) Synapse

Q.4) If we step on something sharp accidently we move our foot away at once .what is  this type of response known as?

Ans.4) Reflex action

Q.5) A part of the hind brain makes possible activities like walking, skating, riding a bicycle and picking up a pencil.name this part of the hind brain.

Ans.5) Cerebellum

Q.6) 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.6) a. Goitre

 b. Iodine

Q.7) Name the plant hormone:

   (a) which inhibits growth and causes wilting of leaves.

   (b) which promotes cell division.

Ans.7) a. Abscisic acid.

b. Cytokinins.

Q.8) Taking the example of heart beat, justify the antagonistic action of the sympathetic and the parasympathetic nerves.

Ans.8) Sympathetic system increases contraction and rhythm and parasympathetic system decreases contraction and rhythm with respect to heart beat.

Q.9) Why is abscisic acid known as stress hormone in plants?

Ans.9) Abscisic acid in a plant hormone which inhibits growth. Its effects include wilting of leaves.

Q.10) Name the part of neuron

   (a) where information is acquired.

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

Ans.10) a. Dendrite

b. Axon

Q. 1 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? 1 Mark

1. Compare nervous and hormonal mechanism for control

Ans.

 

Ans. (i) Thyroxin – Control overall metabolic rate of the body (carbohydrate, protein and fat metabolism)

(ii) Insulin – Conversion of glucose to glycogen in liver and muscles, thus decreases blood glucose level.

(iii) Adrenalin – increases heart beat, blood pressure and blood glucose level.

(iv) Growth hormone – Body growth and development of bones.

(v) Testosterone – Development of male sex organ

 

2. Mention one function for each of these hormones.

i) Thyroxine

ii) Insulin

iii) Adrenaline

iv) Growth hormone

v) Testosterone.

 

Ans. (i) Thyroxin – Control overall metabolic rate of the body (carbohydrate, protein and fat metabolism)

(ii) Insulin – Conversion of glucose to glycogen in liver and muscles, thus decreases blood glucose level.

(iii) Adrenalin – increases heart beat, blood pressure and blood glucose level.

(iv) Growth hormone – Body growth and development of bones.

(v) Testosterone – Development of male sex organ sand secondary sex characteristics like moustache, beard & voice.

 

3. a) what are hormones?

b) list four characteristics of hormones

 

Ans. Hormones are chemical substances which are secreted in very less amount by specialized tissues called endocrine glands.

Characteristics of hormones are –

1) They are required in very less amount.

2) Hormones are specific in their function.

3) They act away from the site of production.

4) Deficiency or over secretions of hormones have negative effects in the body.

 

4. Design an experiment to demonstrate hydrotropism.

Ans. a) Take two glass troughs A and B and fill each one of them two – thirds with soil.

b) In troughs A plant a tiny seedling. In trough B plants a similar seedling and places a clay pot inside the soil.

c) Water the soil in trough A daily and uniformly. Do not water the soil in trough B but put some water in clay pot and leave both the trough for a few days.

d) Now, dig up the seedling carefully form both the troughs without damaging their roots. Observation –Roots of seedling in trough in A is straight. The root of seedling in trough B is bent to the right side i.e.,toward the clay pot containing water.

5. Describe Nervous system in humans.

Ans.

 

Flow chart of human nervous system

 

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

 

Ans. Neuron acquires particular information through dendrite located on its cell body. This information is then passed on to the axon. Finally, axon ending

passes the information into next neuron at the synapse. As soon as the impulse reaches the dendrite, an electrical impulse is generated due to certain chemical changes in neuron. When the impulse reaches axon ending some chemicals

released which pass on the impulse to next neuron. These chemicals are known as neurotransmitters.

1. Junctions of two neurons in called.

d) Cytokinin

 

Ans. d) Cytokinin

 

 

3. When a person is suffering from severe cold, he or she cannot –

 

a) Differentiate the taste of an apple form that of an ice – cream.

 

b) Differentiate red light from green light.

 

c) Differentiate a hot object form a cold object.

 

d) Differentiate the smell of a perfume form that of an agarbatti

 

Ans. (d) Differentiate the smell of a perfume form that of an agarbatti.

 

 

4. What do you mean by geotropism?

 

Ans. Downward movement of roots in response to Gravitational force is called geotropism.

 

 

5. Name the two sets of nerves that constitute the peripheral nervous system.

 

Ans Sympathetic nervous system and Parasympathetic nervous system.

 

 

6. The brain is lodged inside the cavity of skull known as :

 

a) Piamater

 

b) Duramater

 

c) Cranium

 

d) Meninges

 

Ans. c) Cranium

 

 

7. Electrical impulse travels in a neuron from –

◊ Brain (i) Centre of coordination of all activities (ii) Thinking is involved (iii) Complex process

 

◊ Parts of brain- Refer to figure 7.3 page no. 118 of N.C.E.R.T Text book

 

◊ Fore brain

Cerebrum- (i) Main thinking and largest part of the brain. 

                (ii) It has 3 main areasa.

                       a.Sensory area- to receive impulses from sense organs via Receptors

                       b. Motor area- control voluntary movements.

                       c. Association areas- Reasoning, learning & intelligence.

Thalamus – It relays sensory information to the Cerebrum

Hypothallamus- It forms the link between Nervous system & Endocrine system

 

◊Mid brain- It connects Fore brain and Hind brain. Controls reflex of eyes & ears

 

◊ Hind brain- Connects the Fore brain & Hind brain

 

Cerebellum – Controls & coordinates muscular movements, maintaining body posture and equilibrium.

 

Pons- Acts as a bridge between brain & spinal cord

 

Medulla oblongata- Controls involuntary actions like blood pressure, salivation, vomiting, etc.

 

◊Spinal cord- Cylindrical or tubular structure extending downwards from the Medulla oblongata.

 

◊ Protection of the brain & the spinal cord-

(i) Bony outer covering: skull for the brain & vertebral column for the spinal cord.

(ii) Cerebrospinal fluid present in between the three membranes.

 

◊ Action caused by Nervous tissue

Information → Nervous tissue → Brain Muscles → Causes action 

 

◊ Path or action-

Nerve impulse → Muscle cell →  Changes shape due to special proteins

 

  Action caused ← Shorter form of muscles  ←  Change shape & arrangement of cell

 

◊ Chemical communication by hormones- (advantages)

(i) Electrical impulses have their limitations because they reach only those cells connected to the nervous tissue.