Extra Questions for Class 10 Science Chapter 7 Control And Coordination

Extra Questions for Class 10 Science Chapter 7 Control And Coordination

Q.1. Define reflex action.

Answer: A reflex action or also known as reflex is the sudden action given in response to any activity. These are the involuntary movement. Reflex action does not involve the conscious part of the brain. The path of impulses in reflex action is known as reflex arc.
For example when we touch the hot pan by mistake we suddenly pull-off our hands. This response to the stimuli is known as reflex action.

Q.2. Name the structural and functional unit of nervous system.

Answer: Neurons are the structural and functional unit of human nervous system. Parts of neuron are dendrite, nucleus, cell body, axon and nerve ending. All the information is received from dendrites and through nerve ending is passed to the next neuron.

Q.3. What is detected by gustatory receptors?

Answer: Gustatory receptors detect the taste. They are distributed over the surface of the tongue in individual organs called taste buds. Like olfactory receptors will detect smell.

Q.4. Which part of the brain helps us to focus on the objects?

Answer: Fore-brain helps us to focus on the objects. In fore-brain occipital lobe is responsible for processing the sight.

Q.5. Which plant hormone is a growth inhibitor?

Answer: Abscisic acid is the growth inhibitor hormone that is it stops the growth of the plant. Because of this hormone wilting of leaves is seen.

Q.6. What is common in plants like pea, pumpkin, and cucumber?

Answer: They all show the growth of tendrils which are sensitive to touch. When tendrils come in contact with the support, the part which is not in contact with the support tends to grow fast and tendrils circles around the object or the support and clings over the object.

Q.7. At which point information is acquired in the neuron?

Answer: At the end of the dendritic tip information is acquired. After the information is acquired, chemical reaction is set off at the dendritic tip and an electrical impulse is generated. This impulse is passed through axon to its end. At axon end, impulse is set off and again some chemicals are released, which crosses the gap between the two nerve cells and again starts the same procedure in the second nerve cell.

Q.8. Neuron is the longest cell but does not undergo cell division. Why is it so?

Answer: Centriole is responsible for carrying out cell division but in neurons, centrioles are absent so they do not divide. Another reason why neurons don’t divide is that they are linked with a brain so each time it will become difficult for the brain to reset the memory. That is why neurons do not divide.

Q.9. Name the structure that helps in the protection of the spinal cord.

Answer: Spinal cord is protected by the vertebral column, also known as the backbone. It is a hard and bumpy structure which protects the spinal cord.

Q.10. Give an example of chemotropic movement.

Answer: Chemotropic movement means movement in the direction of the chemicals. For example, growth of pollen tube towards the ovule during fertilisation.

Q.11. Blood pressure and heart rate will be regulated by which part of the brain?

Answer: Hind part Medulla oblongata is responsible for the control of involuntary activities such as breathing, blood pressure (BP) etc.

Q.12. Why is there a need for chemical communication in organisms?

Answer: In an organism cells cannot continuously create and transmit electrical impulses. Thus most multicellular organism use another means of communication between different cells, called the chemical communication.
In this A chemical compound is released, which would diffuse all over around the original cells. Other, cell around will detect the compound using special molecules. They can recognize and transmit the information carried by it. These compounds are called hormones.

Q.13. Why do muscles change their shape in response to a nerve impulse?

Answer: In order to cause the movement of muscles, muscles change their shapes and arrangement in cell in response to nervous impulse. The new arrangement of proteins thereby, give the muscle cells a shorter form and move in direction according to the mind.

Q.14. How does adrenaline prepare us for the stress situations?

Answer: In stress situations adrenaline is released into the blood by adrenal glands. Its target organ is heart which as results heart rates increases so as to increase the supply of the oxygen to the muscles, blood to digestive system and skin is reduced and breathing rate increases. All these responses together prepare the body to face any stressful situation.

Q.15. If the effectors are missing in the reflex arc, what will happen?

Answer: Effectors are nothing but the muscles itself. If it is absent then the movement of the hand after receiving the signal won’t be possible since there is no organ to act upon the electric impulse. For example, in case we touch hot pan then in the absence of effectors, we won’t be able to pull back our hand

Q.16. How auxin helps in the bending of shoots towards a light source?

Answer: In the presence of light auxin is released or is synthesized at the tip of the shoot which helps the cells to grow. When the light comes from one side, auxin diffuse towards the shady part of the shoot. This concentration of auxin elongates the cells of the shady part of the shoot and hence it appears that the plant is bending towards the light.

Q.17. The highest concentration of cytokinin is found in which area?

Answer: Cytokinin are the hormones which promote cell division. Highest concentration of cytokinin is found in the areas of rapid cell division like fruits and seeds.

Q.18. Adrenal glands are located on top of each kidney. What will happen if these glands do not secrete adrenaline?

Answer: If these glands do not secrete adrenaline then our body won’t get prepared for stressful situations. Also, there are many disorders like Addison’s disorder which a person might have to face such disorders.

Q.19. What will happen if the intake of iodine in our diet is low?

Answer: If there is iodine deficiency then production of thyroxin stops and as a result, the neck swells and this condition is known as goitre. Iodine is very important for the production of thyroxine hormone.

Q.20. What are receptors with reference to the nervous system? List three types of receptors and mention their functions. How do receptors pass the information to the brain?

Answer: Receptors are tissues which are capable of receiving any stimuli and start the impulse which is passed to the CNS.
Three types of receptors are: –

1. Olfactory receptor: – They detect the smell
2. Gustavo receptor: – They detect the taste
3. Thermoreceptor: – they detect the temperature of the outer world.
   Receptor through sensory-motor passes the information to the spinal cord which then
   sends the information to the brain.

Q.21. Mention the function of the hind-brain in humans.

Answer. Hind brain controls respiration, cardio-vascular reflexes and gastric secretions.
It also modulates the motor commands initiated by the cerebrum.

Q.22. A young green plant receives sunlight from one direction only. What will happen to its shoots ?

Answer. Shoots will bend towards the light and roots away from the light.

Q.23. How is the spinal cord protected in the human body?

Answer. Spinal cord is enclosed in a bony cage called vertebral column.

Q.24. A potted plant is made to lie horizontally on the ground. Which part of the plant will show
(i) positive geotropism?
(ii) negative geotropism?

Answer.
(i) Root (ii) Shoot.

Q.25. Mention the function of adrenaline hormone.

Answer. Adrenaline hormone is released into the blood from the adrenal gland during stimulation of the nervous system on seeing any adverse situation of fight or fright, it increases the blood pressure, it increases heart beat rate, it increases breathing rate and it diverts blood to essential organs including the heart, brain and skeletal muscles by dilating their blood vessels and constricting those of less essential organs, such as the skin and digestive system.

Q.26. What is the function of thyroxine hormone in our body ?

Answer. Thyroxine hormone regulates the carbohydrate, protein and fat metabolism in the body
so as to provide the best growth balance.

Q.27. Mention the part of the body where gustatory and olfactory receptors are located.

Answer. Gustatory receptors are located in Cerebrum of fore-brain. Olfactory receptors are
located in Olfactory lobe of fore-brain.

Q.28. Name the part of the brain which controls posture and balance of the body.

Answer. Cerebellum in hind-brain controls the posture and balance of the body.

Q.29. Name two tissues that provide control and coordination in multicellular animals.

Answer. The two tissues that provide control and coordination in multicellular animals are
nervous and muscular tissues.

Q.30. Name the plant hormones which help/promote (i) cell division (ii) growth of the stem and roots?

Answer. The plant hormones which help or promote:
(i) Cell division — Cytokinins
ii) Growth of the stem — Gibberellins

Q.31. Which one of the following actions on touch is an example of chemical control?
(i) Movement on the touch-sensitive plant.
(ii) Movement in human leg.

Answer.
(i) Movement on the touch-sensitive plant.

Q.32. Why is it advised to use iodised salt in our diet ?

Answer. Iodine stimulates the thyroid gland to produce thyroxin hormone. Deficiency of this
hormone results in the enlargement of the thyroid gland. This can lead to goitre.

Q.33. State the function of:
(i) gustatory receptors, and
(ii) olfactory receptors.

Answer. (i) Gustatory receptors – these are sensitive to taste
(ii) Olfactory receptors – these are sensitive to smell.

Q.34. Where are Nissl’s granules found and what is their nature?
Answer. Nissl’s granules are found in cyton and dendrites. These are formed of ribonucleic acid
(RNA).

Q.35. State how concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light ?
Answer. When light falls on the side of the shoot auxin diffuses towards the shady side of the
shoot. This concentration of the auxin stimulates the cell to grow longer on the side of the shoot
which is away from light. Thus plant appears to bend towards light.

Q.36. What is the significance of reflex action?
Answer. Reflex action enables the animal to respond quickly and relieves the brain from excess
work.

Q.37. Name the two components of central nervous systems in humans.
Answer. The two components of Central Nervous System in human are brain and spinal cord.

Q.38. Give an example of a plant hormone that promotes its growth. Where it is synthesized ?
Answer. Plant hormone that promotes growth is auxin. It is synthesized at the tip of the plant
stem.

Q.39. Name the fluid that is found between the meninges.
Answer. Cerebrospinal fluid.

Q.40. Give one example of chemotropism.
Answer. The growth of pollen tube towards a chemical produced by ovule during fertilisation of
flower is an example of chemotropism.

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