CBSE Class 10 Science Chapter 7 Control and Coordination Short Answer Questions

CBSE Class 10 Science Chapter 7 Control and Coordination

Hormones In Animals:

CBSE Class 10 Science Chapter 7 Control and Coordination Short Question And Answers

Question 1. What is the difference between a reflex action and walking?
Answer:

Question 2. What happens at the synapse between two neurons?
Answer:

At the synapse at the end of the axon of the neuron carrying information, the electrical impulse sets off the release of some chemicals, known as neurotransmitters. These chemicals cross the gap (synapse) reach the dendrites of the next neuron and start electrical impulses there.

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Question 3. Which part of the brain maintains posture and equilibrium of the body?
Answer: A part of the hindbrain known as the cerebellum maintains posture and equilibrium of the body.

Question 4. How do we detect the smell of an agarbatti (incense stick)?
Answer: The smell of an agarbatti is sensed by the olfactory receptor present in the nose. They send information to the olfactory lobe, located in the forebrain, which interprets the data.

Question 5. What is the role of the brain in reflex action?
Answer:

Nerves from all over the body meet in a bundle in the spinal cord on their way to the brain. Reflex arcs are formed in the spinal cord itself. So the input (stimulus) and output (response) actions are completed quickly, although the information input also reaches the brain. The brain may store the experience for the future.

Question 6. What are plant hormones?
Answer:

Plant hormones are special chemical compounds released by different parts of the plants. They help to coordinate growth, development, and responses to the environment. They are synthesized at places away from the site where they act. They diffuse to the area of action.

Question 7. How is the movement of leaves of the sensitive plant different from the movement of a shoot toward light?
Answer:

Differences between the movements of the leaves of the sensitive plant and the movement of the shoot toward light are as follows:

• The movement of leaves of the sensitive plant is not directional to the stimulus of touch. But the movements of the shoot are directional towards the light.
• The movement of leaves (drooping down) of sensitive plants is due to changes in the amount of water present in them. The movement of the shoot towards light is due to growth controlled by a growth hormone called auxin.

Question 8. Give an example of a plant hormone that promotes growth.
Answer:

Auxin promotes the growth of the cell, gibberellins help in the growth of the stem, and cytokinin promotes cell division (any of them).

Question 9. How do auxins promote the growth of a tendril around a support?
Answer:

The tendrils are sensitive to touch. When a part of the tendril comes in contact with a support, the growth hormone auxin diffuses from the site. This causes growth in the part of the tendril away from the support. This causes the tendril to circle the support. Thus, the tendril clings to the support.

Question 10. Design an experiment to demonstrate hydrotropism.
Answer:

Experiment to demonstrate hydrotropism: Growth movements in response to the stimulus of moisture (water) are termed hydrotropic movements (Hydrotropism).

Experiment: Place some ready-to-germinate seeds of pea/gram/beam in moist sawdust in a shallow box whose bottom has been replaced by a wire gauze.

Keep the apparatus undisturbed for 2-3 days. Keep the sawdust moist. After some time radicles will pass through the sieves. Then the radicles curve upward again to enter into the moist sawdust.

The roots are positively hydrotropic and the curvature is more than that due to the geotropic effect.

Question 11. How does chemical coordination take place in animals?
Answer:

In animals, chemical coordination is carried out by hormones secreted by endocrine glands. Hormones are secreted by ductless glands placed far away from the site of action of the secreted hormone.

1. Hormones are directly secreted into the blood that carries them to different parts of the body and also to tissues/organs where they are required.
2. The body cells have special molecules on their plasma membrane for recognition of information a hormone carries. After receiving hormonal information the organ/tissues/cells act accordingly.

Question 12. Why is the use of iodized salt advisable?
Answer:

Iodine is necessary for the synthesis of the thyroid glands’ thyroxin hormone. Thyroxin regulates carbohydrates, fat, and protein metabolism in the body to maintain the best balance for growth.

1. The deficiency of iodine may cause a decrease in the production of thyroxine resulting in goiter disease and other metabolic disorders. The main symptom of goiter is a swollen neck.
2. As a preventive measure, people are advised to use iodized common salt.

Question 13. How does our body respond when adrenaline is secreted into the blood?
Answer: Adrenaline is secreted by the adrenal gland directly into the blood. The target organs or the specific tissues on which it acts include the heart.

Response due to secretion of adrenaline

1. The heart beats faster, resulting in a supply of more oxygen to our muscles.
2. The blood to the digestive system and skin is reduced and diverted to our skeletal muscles.
3. Breathing rate increases because of contraction of the diaphragm and the rib muscles. All these responses together enable our body to be ready to deal with the adverse situation.

Question 14. Why are some patients with diabetes treated by giving injections of insulin?
Answer:

Insulin is a hormone secreted by the pancreas. It helps in regulating blood sugar levels. It is not secreted in proper amounts, and the sugar level in the blood rises causing many harmful effects. Doctors treat diabetic patients with high blood sugar levels with insulin injections to keep blood sugar levels under control.

Question 15. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
Answer:

Receptors are specialized tips of some nerves that are located in our sense organs such as skin, tongue, etc.

• They detect information from the environment and pass on the information to the spinal cord and brain for proper response. If receptors do not work properly, there will be a delay in responding to a stimulus.
• This sometimes becomes dangerous. For example, touching a hot object is an urgent and dangerous situation for us. We need to detect it and respond to it immediately.

Question 16. Draw the structure of a neuron and explain its function.
Answer:

Diagram of a neuron to show its structure:

The function of neurons is to carry messages over long distances in the body of a person quickly. The message that neurons transmit in the nervous system is in the form of electrical impulses. Neurons make the whole nervous system work efficiently.

For example, the sensory neurons transmit impulses from the sensory cell towards the central nervous system and the motor neurons transmit impulses from the central nervous system towards the muscle cells for taking appropriate action.

Question 17. How does phototropism occur in plants?
Answer:

The directional (or tropic) movements due to light, in plants are called phototropic movements. In this case shoot of the plant grows towards the direction of light whereas roots grow away from the light stimulus.

Question 18. Why does the shoot bend toward the light?
Answer:

The growth hormone, auxin, is not able to promote growth in the plant part which is well-illuminated, from one side. So, the hormone auxin diffuses toward the shady side of the shoot.

• The increased concentration of growth hormone auxin in the shaded part of the shoot causes an increase in the growth of cells in that region.
• The enhanced growth of the shaded side of the shoot i.e., one side of the shoot, causes the bending of the shoot towards the source of light.

Question 19. Which signals will get disrupted in case of a spinal cord injury?
Answer:

1. Reflex action, as information detected from the environment, will be conveyed late to the reflex arc and response to the signal may be delayed to reach the effector organ/tissues. They may lead to dangerous situations. The signal of touching a hot object, if delayed, may lead to delayed response and we may get hurt.
2. Information detected by nerves from various parts of the body may reach the spinal cord/brain late.
3. Message from the brain will not be conducted to various organizers: This will lead to disturbed control and coordination of the organism.

Question 20. How does chemical coordination occur in plants?
Answer:

Plants do not have a nervous system for control and coordination. They may have the following system:

1. By making movements dependent on growth such as bending of the shoot towards the source of light. For such actions, plants produce hormones, such as auxins, cytokinins, etc.
2. Movements that are independent of growth like shrinking or swelling as happens in touch-me-not plants.
3. The plants also use electrical-chemical means to convey information from cell to cell, as happens in the drooping of leaves on touch.

Question 21. What is the need for a system of control and coordination in an organism?
Answer:

Living organisms make many movements, which may be due to growth, in response to changes in the environment or to procure food. Each kind of change in the environment evokes an appropriate movement in response.

In multicellular organisms, different body parts or body organs must work in unison for the survival of the individual. In other words, living organisms must use systems providing control and coordination.

Question 22. How are involuntary actions and reflex actions different from each other?
Answer:

Question 23. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Answer:

Question 24. What is the difference between how movement takes place in a sensitive plant and the movement in our legs?
Answer:

The difference between movement in a sensitive plant and the movement in our legs

Question 25. State the functions of any three of the structural and functional units of the nervous system.
Answer:

The structural and functional unit of the nervous system is a neuron. Its functions are as follows:

1. Cell body: Stimulus received from dendrite is changed into an impulse in the cyton.
2. Dendrites: They receive sensation or stimulus, which may be physical, chemical, mechanical, or electrical. They pass the stimulus to cyton.
3. Axon: It conducts impulses away from the cell body.

Question 26.

1. Which plant hormone is present in greater concentration in the areas of rapid cell division?
2. Give one example of a plant growth promoter and a plant growth inhibitor.

Answer:

1. Cytokinin is present in greater concentration in the areas of rapid cell division.
2. An example of a plant growth promoter is gibberellins and an example of a plant growth inhibitor is abscisic acid.

Question 27. Suggest proof that even unicellular organisms like amoeba respond to stimuli. Justify by giving two examples that even plants respond to stimuli.
Answer:

Amoeba moves towards food and tends to aggregate in moderately warm water. Amoeba and other protozoa avoid mechanical obstacles.

Thus, unicellular organisms respond to stimuli. Roots of plants move downward in response to gravitational force and shoots of plants move towards light. This shows that plants respond to stimuli.

Question 28.

1. Name the part of the brain that controls:
   1. Voluntary action.
   2. Involuntary action.
2. What is the significance of the peripheral nervous system? Name the components of this nervous system and distinguish between the origin of the two.

Answer:

1. 1. Voluntary action – cerebellum;
   2. Involuntary action – medulla oblongata.
2. The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system. Cranial nerves arise from the brain; spinal nerves arise from the spinal cord.

Question 29. State how the concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light.
Answer:

When a growing plant detects light, auxin synthesizes at the shoot tip to help the cell to grow longer. When light comes from one side, auxin diffuses towards the shady side of the shoot.

This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light and the plant appears to bend towards light.

Question 30.

1. Explain any three directional movements in plants.
2. How are the brain and spinal cord protected in humans?
3. Name the master gland present in the brain.

Answer:

1. Three directional movements in plants are:
   1. Phototropism: It is the movement of a part of a plant towards light, e.g., the movement of the stem towards light.
   2. Geotropism: The upward and downward growth of shoots and roots in response to gravity is called geotropism.
   3. Chemotropism: It is the movement of a part of a plant in response to a chemical stimulus, e.g., the growth of a pollen tube towards a chemical produced by an ovule.
2. The brain and spinal cord are protected by a skeleton – the brain by the cranium and the spinal cord by the vertebral column.
3. The master gland present in the brain is called the pituitary gland.

Question 31.

1. An old man is advised by his doctor to take less sugar in his diet. Name the disease from which the man is suffering. Mention the hormone due to imbalance of which he is suffering from this disease. Which endocrine gland secretes this hormone?
2. Name the endocrine gland which secretes growth hormone. What will be its effect on a person of:
   1. Deficiency of growth hormones?
   2. Excess secretion of growth hormone?

Answer:

1. The man is suffering from the disease Diabetes. Insulin is the hormone that is responsible for this disease. The pancreas secretes this hormone.
2. The gland that secretes the growth hormone is the pituitary gland.
   1. Deficiency of growth hormone causes Dwarfism.
   2. Excess secretion of growth hormone causes Gigantism in a person.

Question 32. Distinguish between estrogen and progesterone.
Answer:

Question 33.

1. Identify the phytohormone used by plants while performing the following functions:
   1. Cell division in shoot tip.
   2. Inhibiting growth on the approach of unfavorable conditions.
2. List in tabular form two differences between the movement in the ‘touch-me-not’ plant and the movement of the shoot towards the light.

Answer:

1. Auxin,
2. Abscisic acid.

Question 34. How does chemical coordination occur in plants? Explain with the help of three examples.
Answer:

In plants, chemical coordination occurs through various phytohormones.

1. Auxins are secreted by growing tissues. They provide growth of plants.
2. Gibberellins cause stem elongation, seed germination, and flowering.
3. Cytokinins are present in areas of actively dividing cells like fruits and seeds. Promote cell division.
4. Abscisic acid inhibits growth and responds to environmental stress. (any three)

Question 35. Draw a neat diagram of the human brain and label it the following parts:

1. Midbrain
2. Pituitary gland

Answer:

Question 36. Illustrate with the help of a diagram, the effect of auxins in different parts of a plant.
Answer:

Question 37. List the names of hormones secreted by the following endocrine glands and mention their functions:

1. Thyroid gland
2. Adrenal gland
3. Pituitary gland

Answer:

Question 38. Write one example of each of the following tropic movements:

1. Positive phototropism
2. Negative phototropism
3. Positive geotropism
4. Hydrotropism
5. Negative geotropism
6. Chemotropism

Answer:

1. Positive phototropism: Movement of the stem of a plant towards light.
2. Negative phototropism: Movement of roots away from light.
3. Positive geotropism: Movement of roots towards gravity.
4. Negative geotropism: Upward movement of shoots.
5. Hydrotropism: Growth of roots of a plant towards the water in the soil.
6. Chemotropism: Growth of pollen tubes towards ovule.

Question 39. Describe an activity to illustrate the phenomenon of phototropism and explain why this occurs.
Answer:

Activity:

Take a plant and make such an arrangement that it receives the light coming from a window as shown in the figure and observe it for a few days.

• Now, turn the flask so that the shoots are away from light and the roots towards light. Leave it undisturbed in this condition for a few days.
• Again observe to find the difference in the movement.
• When growing plants detect light, auxin, synthesized at the shoot tip, helps the cells to grow longer; auxin always diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.

Question 40. What is a cerebrospinal fluid? What is its function?
Answer:

The fluid which fills the space between the membranes which cover the brain is called cerebrospinal fluid.

Function: It protects the brain from mechanical shocks.

Question 41. What is a reflex arc?

1. What are the components of the reflex arc?
2. How do muscle cells move?

Answer:

1. The process of detecting the signal or the input and responding to it by an output action might be completed quickly. Such a connection is commonly called a reflex arc.
2. Stimulus → Receptors → Sensory neurons → Spinal cord → Motor neurons → Effector.
3. Muscle cells have special proteins that change their shape and arrangement in the cell in response to electrical impulses. This leads the muscle cells to shorten.

Question 42. Write the difference between the cerebellum and cerebrum.
Answer:

Question 43. ‘Brain and spinal cord are two vital organs of our body’. How is our body designed to protect them?
Answer:

The brain is inside a bony box contained in a fluid-filled balloon which protects it from shocks. The vertebral column protects the spinal cord. Both are protected by protective layers called meninges, protective fluid (CSF→ cerebrospinal fluid).

Question 44.

1. How does the tendril coil around the support?
2. Define phototropism.

Answer:

1. Tendrils are sensitive to touch. When they come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. This causes the tendril to coil around the support.
2. Movement of plants in response to light.

Question 45. List the sequence of events that occur when a plant is exposed to unidirectional light, leading to the bending of a growing shoot. Also, name the hormone and the type of movement.
Answer:

1. Auxin diffuses towards the shady side.
2. Causes elongation on one side (shady side) resulting in bending of the growing shoot.
3. The hormone responsible for bending is auxin and the movement is phototropic.

Question 46.

1. Name the diseases by which a person is likely to suffer due to the deficiency of:
   1. Iodine
   2. Insulin
2. How is the timing of secretion and amount of hormone secretion regulated in the human system? Explain with an example.

Answer:

1. 1. Goitre
   2. Diabetes
2. The timing and amount of hormone released are regulated by feedback mechanisms, e.g., if the sugar levels in the blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

Question 47.

1. Name the hormone that is injected into a diabetic patient.
2. Why should we use iodized salt in our diet?
3. If iodine is insufficient in one’s diet, what might be the deficiency disease and its symptoms?

Answer:

1. Insulin.
2. Iodine is necessary for the thyroid gland to secrete thyroxine hormone. Thyroxine regulates carbohydrates, proteins, and fat metabolism in the body, to provide the best balance for growth.
3. If iodine is insufficient in one’s diet, an iodine deficiency disease called goiter occurs. The symptom is a swollen neck.

Question 48.

1. If the cerebellum is not functioning properly, what are the activities of our body that will be affected?
2. How do muscle cells move?

Answer:

1. If the cerebellum is not functioning properly, voluntary action of our body will be affected by maintaining the posture and balance of the body.
2. Muscle cells move by changing their shape so that they get shortened.

Question 49. Name a hormone secreted by:

1. Pancreas
2. Pituitary
3. Thyroid. Write one function of each of the hormones.

Answer:

1. Insulin – controls blood sugar levels.
2. The pituitary – growth hormone regulates growth and development.
3. Thyroxine – regulates the metabolism of carbohydrates, fats, and proteins.

Question 50. Define reflex action. Give one example. Show with the help of a flow diagram the path of the reflex action.
Answer:

Reflex action is a sudden action in response to something in the environment. e.g., pulling out a hand from the flame if accidentally touched. The path of the reflex action is as follows:

Receptors Sensory neuron → Spinal cord → Effector → Motor neuron

Question 51. Name the hormone synthesized at the shoot tips. How does it help plants to respond to light?
Answer:

Auxin is synthesized at the shoot tips when a growing plant detects light and helps the cells to grow longer.

When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.

Question 52.

1. Differentiate between sensory neurons and motor neurons.
2. How is the brain protected in our body?
3. Name the part of the brain responsible for the precision of voluntary actions and maintaining body posture and balance of the body.

Answer:

1. Sensory neurons carry impulses from receptors to the brain. Motor neurons carry impulses from the brain to effectors.
2. The brain is kept inside a bony box (skull). Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption. This fluid is known as cerebrospinal fluid (CSF).
3. These are possible due to a part of the hindbrain called the cerebellum.

Question 53. Name and explain the functions of the hormones secreted by the pituitary gland in humans
Answer:

Hormones secreted by the pituitary gland along with their function are as follows:

1. Growth hormone: It regulates the growth and development of bones and muscles.
2. Trophic hormone: It regulates the secretion of hormones from other endocrine glands.
3. Prolactin hormone: It regulates the function of mammary glands in females.
4. Vasopressin hormone: It regulates water and electrolyte balance in the body.
5. Oxytocin hormone: It regulates the ejection of milk during lactation.

Question 54. How do you support the statement the pancreas’ are the overall controller of the blood glucose level?
Answer:

The pancreas releases insulin which lowers blood glucose. Moreover, it also releases glucagon which increases blood glucose. Therefore, the pancreas is the overall controller of blood glucose levels.

Question 55. Name the two main organs of our central nervous system. Which one of them plays a major role in sending commands to muscles to act without involving the thinking process? Name the phenomenon involved.
Answer:

The two main organs of the CNS are the brain and spinal cord. The spinal cord plays a major role in sending commands to muscles to act without involving the thinking process. This phenomenon is called reflex action.

Question 56. Label the parts (a), (b), and and show the direction of the flow of electrical signals in the figure given below:

Answer:

1. Sensory neuron
2. Spinal cord
3. Motor neuron
4. Effector = Muscle in the arm

Question 57. Name the plant hormones responsible for the following

1. Elongation of cells
2. Growth of stem
3. Promotion of cell division
4. Falling of senescent leaves.

Answer:

1. Auxin
2. Gibberellin
3. Cytokinin
4. Abscisic acid.

Question 58. Label the endocrine glands in the figure given below:
Answer:

1. Pineal gland
2. Pituitary gland
3. Thyroid
4. Thymus.

Question 59. In figure (a), and given below, which appears more accurate and why?

Answer:

The figure is more appropriate because in a plant shoot is negatively geotropic and hence grows upward while roots are positively geotropic, so grow downward.

Question 60. Label the parts of a neuron in the figure given below:

Answer:

1. Dendrite
2. Cell body
3. Axon
4. Nerve ending.

Question 61. Match the terms of Column (A) with those of Column (B)

Answer: 1-C, 2-D, 3-A, 4-B

Question 62. What is a tropic movement? Explain with an example.
Answer:

The directional growth movements of plants due to external stimuli are called tropic movements. These can be either towards the stimulus, or away from it. For example, in the case of phototropic movement, shoots respond by bending toward light while roots respond by bending away from it.

Question 63. What will happen if the intake of iodine in our diet is low?
Answer:

1. When iodine intake is low, the release of thyroxin from the thyroid gland will be less, by which protein, carbohydrate, and fat metabolism will be affected.
2. A person might suffer from goiter in case of iodine deficiency in the body.

Question 64. What happens at the synapse between two neurons?
Answer:

When an electrical signal reaches the axonal end of one neuron, it releases certain chemical substances that cross the synapse and move towards the dendritic end of the next neuron generating another electrical signal.

Question 65. Answer the following:

1. Give the names of hormones responsible for the physical changes in a boy and a girl.
2. Name the element of the halogen family required for the proper functioning of the thyroid gland.
3. Name the stress and fear hormones.

Answer:

1. Boy – Testosterone Girl – Oestrogen.
2. Iodine.
3. Adrenaline.

Question 66. What is a cerebrospinal fluid? What is its function?
Answer:

The fluid which fills the space between the membranes which cover the brain is called cerebrospinal fluid.

Function: It protects the brain from mechanical shocks.

Question 67. Define ‘nerve impulse’. Which structure in a neuron helps to conduct a nerve impulse?

1. Towards the cell body?
2. Away from the cell body?

Answer:

The pieces of information passing through neurons are in the form of chemical are electrical signals called nerve impulses.

1. Nerve impulses are carried by dendrites towards the cell body.
2. The axon is a highly specialized nerve fiber that conducts nerve impulses away from the cell body.

Question 68. ‘Brain and spinal cord are two vital organs of our body’. How is our body designed to protect them?
Answer:

The brain is inside a bony box contained in a fluid-filled balloon which protects it from shocks. The vertebral column protects the spinal cord. Both are protected by protective layers called meninges, protective fluid (CSF → cerebrospinal fluid).

Question 69. Give reasons:

1. The pituitary is often termed as a master endocrine gland.
2. The pancreas helps in digestion and also regulates blood sugar levels.
3. Adrenals are known as glands of emergency.

Answer:

1. The pituitary is often called the master endocrine gland because it controls and coordinates the secretion of all the other endocrine glands.
2. The pancreas secretes pancreatic juice as well as a hormone called insulin. Pancreatic juice helps in digestion whereas insulin regulates blood sugar levels.
3. Adrenalin is secreted directly into the blood and is carried to different parts of the body. It acts on the heart. As a result, the heart beats faster to supply more oxygen to our muscles. The blood to the digestive system and skin is reduced due to the contraction of muscles around.

Question 70. Answer the following:

1. Name the endocrine gland associated with the brain.
2. Which gland secretes digestive enzymes as well as hormones?
3. Name the endocrine gland associated with the kidneys.
4. Which endocrine gland is present in males but not in females?
5. Which hormone is responsible for changes in females during puberty?
6. Iodine is necessary for the synthesis of which hormone?

Answer:

1. Pituitary gland
2. Adrenal gland
3. Oestrogen
4. Pancreas
5. Testes
6. Thyroxin

Question 71. Vijay’s friend has diabetes and every day after her meal in the recess she had to check her sugar level. To monitor it at times she used to take injections also. Vijay was very fond of sweets but she never carried any sweets in her tiffin.

1. What is the cause of diabetes?
2. What helps in the digestion of sugars?
3. What value of Vijay is reflected in the above act?

Answer:

1. Deficiency of an enzyme that can digest the sugar.
2. Insulin hormone.
3. Sympathy, empathy, and kindness.

Question 72. Akash and Tarun planned to visit a nursery to purchase seasonal flowering plants. While walking in the nursery, Prakash saw a Mimosa pudica (sensitive plant). He asked Akash to touch the leaflets of the Mimosa plant. The leaflets of the plant closed up. Answer the following questions based on the above information:

1. What do you infer from this activity?
2. What would you do based on your inference?

Answer:

1. Mimosa pudica (touch-me-not or sensitive plant) responds to the stimulus of touch by closing of leaflets.
   • Like animals, plants are also living and show movement and response to stimuli.
2. We would organize campaigns to create awareness amongst the masses that plants are living things.

Question 73. Ram and Shyam were doing their homework when Ram’s mother called Ram. She asked Ram to bring a packet of common salt from the market. She asked him to check that the packet bears the label ‘Iodised salt’ or ‘enriched with Iodine’. Shyam also accompanied Ram to bring the packet.

1. Ram asked Shyam, why is it important for us to have iodized salt in our diet? Ram said iodine is necessary for the formation of thyroxin hormone.
2. Answer the following questions based on the above information:
3. Which endocrine gland secretes thyroxin hormone?
4. Which disease can occur in case iodine is deficient in our diet?
5. What will you do to spread awareness among other community members about the use of iodized salt?

Answer:

1. Thyroid gland.
2. Goitre may occur.
3. Organizing awareness programs among society.

Question 74. Tarushi’s mother always kept bananas in polybags and found them to be spoiled. Tarushi suggested her mother not keep the banana in a polybag.

1. Why should we not keep bananas in polybags?
2. Name the hormone present at the root and shoot of the plants.
3. What value of Tarushi is found in this case?

Answer:

1. Ethylene is released from polybag that helps in the ripening of fruits.
2. Auxin hormone.
3. Showed the value of a concerned and responsible child.

Control and Coordination Multiple Choice Questions

Question 1. Which of the following statements is correct about receptors?

1. Gustatory receptors detect taste while olfactory receptors detect smell
2. Both gustatory and olfactory receptors detect smell
3. Auditory receptors detect smell and olfactory receptors detect taste
4. Olfactory receptors detect taste and gustatory receptors detect smell

Answer: 1. Gustatory receptors detect taste while olfactory receptors detect smell

Question 2. The electrical impulse travels in a neuron from

1. Dendrite → axon → axonal end → cell body
2. Cell body → dendrite → axon → axonal end
3. Dendrite → cell body → axon → axonal end
4. Axonal end → axon → cell body → dendrite

Answer: 3. Dendrite → cell body → axon → axonal end

Question 3. In a synapse, a chemical signal is transmitted from

1. The dendritic end of one neuron to the axonal end of another neuron
2. Axon to the cell body of the same neuron
3. Cell body to the axonal end of the same neuron
4. Axonal end of one neuron to dendritic end of another neuron

Answer: 4. Axonal end of one neuron to dendritic end of another neuron

Question 4. In a neuron, the conversion of the electrical signal to a chemical signal occurs at /in

1. Cell body
2. Axonal end
3. Dendritic end
4. Axon

Answer: 2. Axonal end

Question 5. Which is the correct sequence of the components of a reflex arc?

1. Receptors → Muscles → Sensory neuron → Motor neuron → Spinal cord
2. Receptors → Motor neuron → Spinal cord → Sensory neuron → Muscle
3. Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
4. Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Answer: 4. Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Question 6. Which of the following statements is true?

1. Sudden action in response to something in the environment is called reflex action
2. Sensory neurons carry signals from the spinal cord to muscles
3. Motor neurons carry signals from receptors to the spinal cord
4. The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc
   1. 1 and 2
   2. 1 and 3
   3. 1 and 4
   4. 1, 2 and 3

Answer: 3. 1 and 4

Question 7. Which of the following statements are true about the brain?

1. The main thinking part of the brain is the hindbrain
2. Centers of hearing, smell, memory, sight, etc., are located in the forebrain
3. Involuntary actions like salivation, vomiting, and blood pressure are controlled by the medulla in the hindbrain
4. The cerebellum does not control the posture and balance of the body
   1. 1 and 2
   2. 2 and 3
   3. 1, 2 and 3
   4. 3 and 4

Answer: 3. 1, 2 and 3

Question 8. Posture and balance of the body is controlled by

1. Cerebrum
2. Cerebellum
3. Medulla
4. Pons

Answer: 2. Cerebellum

Question 9. The spinal cord originates from

1. Cerebrum
2. Medulla
3. Pons
4. Cerebellum

Answer: 2. Medulla

Question 10. The movement of the shoot towards light is

1. Geotropism
2. Hydrotropism
3. Chemotropism
4. Phototropism

Answer: 4. Phototropism

Question 11. The main function of abscisic acid in plants is to

1. Increase the length of cells
2. Promote cell division
3. Inhibit growth
4. Promote the growth of stem

Answer: 3. Inhibit growth

Question 12. Which of the following is not associated with ith growth plant slant?

1. Auxin
2. Gibberellins
3. Cytokinins
4. Abscisic acid

Answer: 4. Abscisic acid

Question 13. Iodine is necessary for the synthesis of which hormone?

1. Adrenaline
2. Thyroxin
3. Auxin
4. Insulin

Answer: 2. Thyroxin

Question 14. Choose the incorrect statement about insulin

1. It is produced by the pancreas
2. It regulates the growth and development of the body
3. It regulates blood sugar level
4. Insufficient secretion of insulin will cause diabetes

Answer: 2. It regulates the growth and development of the body

Question 15. Select the mismatched pair

1. Adrenaline: Pituitary gland
2. Testosterone : Testes
3. Estrogen: Ovary
4. Thyroxin: Thyroid gland

Answer: 1. Adrenaline: Pituitary gland

Question 16. The shape of guard cells changes due to changes in the

1. Protein composition of cells
2. Temperature of cells
3. Amount of water in cells
4. Position of the nucleus in the cells

Answer: 3. Amount of water in cells

Question 17. The growth of tendrils in pea plants is due to

1. Effect of light
2. Effect of gravity
3. Rapid cell divisions in tendrillar cells that are away from the support
4. Rapid cell divisions in tendrillar cells in contact with the support

Answer: 3. Rapid cell divisions in tendrillar cells that are away from the support

Question 18. The growth of pollen tubes towards ovules is due to

1. Hydrotropism
2. Chemotropism
3. Geotropism
4. Phototropism

Answer: 2. Chemotropism

Question 19. The movement  of sunflobywith path path path that the sun is due to

1. Phototropism
2. Geotropism
3. Chemotropism
4. Hydrotropism

Answer: 1. Phototropism

Question 20. The substance that triggers the fall of mature leaves and fruits from plants is

1. Auxin
2. Gibberellin
3. Abscisic acid
4. Cytokinin

Answer: 3. Abscisic acid

Question 21. Which of the following statements bathe the out transmission of neimpulsesulse is incorrect nerve

1. the nerve impulse travels the rom dendritic end to the rds axonal end
2. At the dendritic, end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron
3. The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron
4. A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells

Answer: 2. At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron

Question 22. Involuntary actions in the body are controlled by

1. Medulla in forebrain
2. Medulla in midbrain
3. Medulla in hindbrain
4. Medullathe  in the spinal cord

Answer: 3. Medulla in hindbrain

Question 23. Which of the following is not an involuntary action?

1. Vomiting
2. Salivation
3. Heartbeat
4. Chewing

Answer: 4. Chewing

Question 24. When a person is suffering fa from a severe cold, he or she cannot

1. Differentiate the taste of an apple from that of an ice cream
2. Differentiate the smell of a perfume from that of an agarbatti
3. Differentiate red light from green light
4. Differentiate a hot object from a cold object

Answer: 2. Differentiate the smell of a perfume from that of an agarbatti

Question 25. What is the correct direction of the flow of electrical impulses?

Answer: 3

Question 26. Which statement is not true about thyroxin?

1. Iron is essential for the synthesis of thyroxin
2. It regulates carbohydrates, pro,tein, and fat metabolism in the bThe thyroidroid gland requires iodine to synthesize thyroxin
3. Thyroxin is also called thyroid hormone

Answer: 1. Iron is essential for the synthesis of thyroxin

Question 27. Dwarfism results due to

1. Excess secretion of thyroxin
2. Less secretion of growth hormone
3. Less secretion of adrenaline
4. Excess secretion of growth hormone

Answer: 2. Less secretion of growth hormone

Question 28. Dramatic chains of body features associated with puberty are mainly because  of the secretion of

1. Oestrogen in the rom testes and testosterone in the rom ovary
2. Oestrogen the the rom adrenal gland and testosterone the the pituitary gland
3. Testosterone the rom testes” estrogenogen the rom ovary
4. Testosterone the thyroid gland estrogenogen from the pituitary gland

Answer: 3. Testosterone the testes estrogenogen from the ovary

Question 29. A doctor advised a person to take an injection of insulin because

1. His blood pressure was low
2. His heart was beating slowly
3. He was suffering from fgoiteritre
4. His sugar levels  in his blood were high

Answer: 4. His sugar levels  in his blood were high

Question 30. The hormone which increases the fertility in males is called

1. Oestrogen
2. Testosterone
3. Insulin
4. Growth hormone

Answer: 2. Testosterone

Question 31. Which of the following endocrine glands is unpaired?

1. Adrenal
2. Testes
3. Pituitary
4. Ovary

Answer: 3. Pituitary

Question 32. The junction between two neurons is called

1. Cell junction
2. Neuromuscular junction
3. Neural joint
4. Synapse

Answer: 4. Synapse

Question 33. In humans, life processes are controlled and regulated by

1. Reproductive and endocrine systems
2. Respiratory and nervous systems
3. Endocrine and digestive systems
4. Nervous and endocrine systems

Answer: 4. Nervous and endocrine systems

Question 34. Which of the following is a plant hormone?

1. Insulin
2. Thyroxin
3. Oestrogen
4. Cytokinin

Answer: Cytokinin

Question 35. The gap between two neurons is called a

1. Dendrite
2. Synapse
3. Axon
4. Impulse

Answer: Synapse

Question 36. The brain is responsible for

1. Thinking
2. Regulating the heartbeat
3. Balancing the body
4. All of the above

Answer: All of the above

Question 37. Answer the following:

1. Which hormone is responsible for the changes noticed in females at puberty?
2. Dwarfism results due to deficiency of which hormone?
3. Blood sugar level rises due to deficiency of which hormone?
4. Iodine is necessary for the synthesis of which hormone?

Answer:

1. Oestrogen
2. Growth hormone
3. Insulin
4. Thyroxin.

Question 38. Answer the following:

1. Name the endocrine gland associated with the ith b.ain.
2. Which gland secretes digestive enzymes as well as hormones?
3. Name the endocrine gland associated with the ith kid. eys?
4. Which endocrine gland is present in males but not in females?

Answer:

1. Pituitary
2. Pancreas
3. Adrenal
4. Testes.