CBSE Class 10 Science Chapter-7 Control and Coordination Important Questions – Free PDF Download
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CBSE Class 10 Science Control and Coordination Chapter-7 Important Questions
CBSE Class 10 science Important Questions Chapter 7 – Control and Coordination
3 Mark Questions
1. Mention three important functions of gibberellins.
Ans. Functions of Gibberllins –
(i) Stimulate stem elongation.
(ii) Help in breaking seed dormancy.
(iii) Promote flowering in some plants even under unfavorable conditions
(iv) Help in seed germination.
(v) Promote production of male flowers.
2. What is the function of receptors in our body? What happens when receptors do not work properly?
Ans. The function of receptors is to defect information form the environment. If receptors do not work properly, the information obtained form the environment will be delayed to reach the spinal cord or brain. In this situation, the response to the environmental stimulus will be delayed causing harm to the body.
3. What happens at the synapse between two neurons?
Ans. The nerve impulse gets transmitted through the synapse by means of chemical signals. When a stimulus acts on the receptor, chemical reaction is set off which produces an impulse in it. This impulse travels form the dendrite of presynaptic neuron to its cell body and then along its axon. At the end of axon of this neuron, the electrical impulse releases tiny amount of a chemical substance crosses the synapse and starts a similar electrical impulse in the dendrite of the next neuron.
4. What is the need for a system of control and co – ordination in an organism?
Ans. a) It evokes an appropriate movement in response to any change in external environment
b) Multicellular organisms have complex body. So it, co – ordinates various organs of body of an organism work together in a proper manner to produce proper reaction to stimulus
5. Pituitary is a master endocrine gland. Justify this statement.
Ans. Pituitary gland is also known as master gland because it controls the activities of most of the gland.
It regulates the secretion of other glands. Like-
a) Growth hormones – Body growth and development of bones
b) Thyroid stimulating hormone – Secretion of hormones form thyroid gland.
c) Adrenocorticotropic hormone – Secretion of hormones form adrenal glands.
d) Follicle stimulating hormone – Stimulating of growth of ovaries and testes
e) Luteinsing hormone – Secretion of hormone from ovaries & testes
f) prolactin – Regulation of function of mammary gland. Hence, most of functions are controlled by pituitary gland so it is called master gland.
6. Draw the structure of neuron and explain its function.
Ans. Neuron has three components –
(i) Cell body
(ii) Dendrites
(iii) Axon
The dendrite picks up the nerve impulse from receptors and then pass the impulses to the cell body and then along the axon. The axon passes the impulse to another neuron through a junction called synapse.
7. How does our body respond when adrenaline is secreted into the blood?
Ans. When adrenaline is secreted into the blood, it prepares our body for action. It speeds up heart beat and breathing, raises blood pressure and allows more glucose to go into the blood to give us a lot of energy quickly to fight or urn away from frightening situation. The blood supply decreases form the skin and digestive system and increase to skeletal muscles. All there conditions help the individual to respond the emergency situation.
8. Where are Pons and medulla oblongata located? Write their functions.
Ans. Pons and medulla Oblongata are located in hind brain.
Pons acts as bridge between brain and spinal cord.
Medulla oblongata –
a) It is the reflex centre to control activities like salivation, swallowing, vomiting, breathing, coughing, sneezing and heart beat
b) It also controls sleeps, consciousness and activities of cerebrum
9. List the function of testosterone and estrogen. Where are they secreted?
Ans. Testosterone is secreted in males – It is responsible for development of male sex organs and secondary sex characteristics like moustache, beard & voice.
Estrogen is secreted in females – it is responsible for development of female sex organs and secondary sex characteristics like mammary gland and uterine growth.
10. Define ‘nerve impulse’. Which structure in a neuron helps to conduct a nerve impulse?
a) Towards the cell body?
b) Away from the cell body?
Ans. Nerve Impulse – It is the passing of information through neurons is in the form of electrical and chemical signals. This is called nerve impulse.
a) Dendrite
b) Axon
11. Differentiate between axon and dendrons?
Ans.
12. Mention the structure of human brain.
Ans.
13. What are tropic movements? Name the types of tropic movements in plants.
Ans. The bending or movement of a part of plant in response to the external stimulus is called tropism or tropical movement. It is of following types.
(a) Phototropism – It is response to light. It may be towards light (positive) or away from the light (negative).
(b) Geotropism – It is response to gravity – It may be towards stimulus (positive) and away from the stimulus (negative)
(c) Chemotropism – Response to chemicals. It may be positive or negative.
(d) Hydrotropism – Response to water. It may be positive or negative.
14. Name the different lobes of cerebrum.
Ans. Different lobes of cerebrum –
a) Frontal lobe – It is associated with reasoning.
b) Parietal – Perception of general sensation s like pressure, touch and pain.
c) Occipital – Visual perception.
d) Temporal – Important for interpreting sounds and the language we hear and formation of memories.
15. How do auxins promote the growth of tendril around a support?
Ans. When the tip of a tendril touches a support, then the auxins present in its tip move to that side of tip which is away form the support, auxins promote growth. So, due to more auxins in it, the side of tendril, away from the support, grow faster and becomes longer than the side which is in contact with the support and makes the tendril curve towards the support.
16. Write different between exocrine and endocrine glands.
Ans.
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.
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.
21. What is the difference between a reflex action and walking?
Ans. Difference between reflex action and walking:
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.
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:
33. Compare and contrast nervous system and hormonal control and coordination in animals.
Ans. Difference between nervous control and hormonal control:
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:
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.