Solutions of Ch - 7 Control and Coordination
I. Very short answer type questions:
1. What is the function of receptors?
Ans. The functions of receptors are to detect test and smell and these receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on.
2. Write the correct sequence of electric impulse travels in a neuron.
Ans. The correct sequence of electric impulse travels in a neuron is -
Dendrite →Cell body → Axon → Nerve ending → Next neuron.
Dendrite →Cell body → Axon → Nerve ending → Next neuron.
3. Where is the conversion of an electric signal to a chemical signal in a neuron occurs?
Ans. In the dendrite, the conversion of an electric signal to a chemical signal in a neuron occurs and creates electric impulse.
4. Which element is necessary for the synthesis of thyroxin hormone?
Ans. Iodine is necessary for the synthesis of thyroxin hormone.
5. Which part of the brain controls voluntary actions?
Ans. the cerebellum which is a part of the hind-brain is responsible for the precision of voluntary actions like walking in a straight line, riding a bicycle, picking up a pencil.
6. Which gland secrets the hormone insulin?
Ans. Insulin is produced by the pancreas and helps in regulating blood sugar levels.
7. All information for our environment is detected by the specialized tip of some nerve cells. Mention the name given to search tips and also mention where are they located?
Ans. The specialized tip is called the dendritic tip of a nerve cell and is usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on.
8. What is the function of the tendril in the pea plant?
Ans. Tendrils provide support to the plants and help to climb.
9. Define chemotropism.
Ans. A chemotropism is a form of tropism in which the plant’s organism grows in response to a chemical stimulus and one example of chemotropism is the growth of pollen tubes towards ovules.
10. Define phototropism.
Ans. Phototropism is a form of tropism in which the plant’s organism grows in response to a light stimulus and one example of phototropism is the growth of the movement of sunflowers in response to day or night.
11. What is the reason for dwarfism?
Ans. Growth hormone is one of the hormones secreted by the pituitary regulates growth and development of the body and if there is a deficiency of this hormone in childhood, it leads to dwarfism.
12. Write three paired glands and one unpaired gland.
Ans. Pair gland- Adrenaline gland, Testis in male, Ovary in the female.
Unpaired gland - Pituitary gland, thyroid gland, pineal gland.
Unpaired gland - Pituitary gland, thyroid gland, pineal gland.
13. What is the junction between two neurons?
Ans. Neuromuscular junction.
14. Which system control and regulate the life processes in human?
Ans. The nervous and endocrine systems control and regulate the life processes in humans.
15. Which hormone increases fertility in males?
Ans. Testosterone hormone increases fertility in males.
16. Which chemical substance is responsible for the formation of abscission which disconnects the living tissue of leaf from the other parts?
Ans. Abscisic acid is responsible for the formation of abscission which disconnects the living tissue of leaf from the other parts.
17. Name the sensory receptors found in the nose and on the tongue?
Ans. Olfactory receptors detect smell which is found in the nose while gustatory receptors detect taste and present in the tongue.
18. Name the part of the brain which controls the posture and balance of the body.
Ans. The cerebellum of the brain is responsible for the precision of voluntary actions and maintaining the posture and balance of the body.
19. Name the two components of the central nervous system in humans.
Ans. The two components of the central nervous system in humans are the brain and spinal cord.
20. Mention that part of the body where gustatory and olfactory receptors are located.
Ans. Gustatory - Tongue
Olfactory - Nose
Olfactory - Nose
21. How do the shoot and root of plant response to the pull of Earth's gravity?
Ans. Upward (negative geotropism) and downward (positive geotropism) growth of shoots and roots, respectively, in response to the pull of earth or gravity, that is geotropism.
22. State the main functions of abscisic acid in Plants.
Ans. Abscisic acid in Plants helps in the wilting of leaves.
23. What is synapse?
Ans. The Synapse is the point of connection between two neurons or between a neuron and a muscle or gland through which electric impulse is delivered.
24. A boy runs on seeing a stray dog, his breathing becomes very fast and blood pressure also increases. Name the hormones found to be high in his blood and the gland which produces it.
Ans. The hormone adrenaline is secreted from the adrenal glands.
25. What is meant by tropic movement?
Ans. Environmental triggers such as light, or gravity will change the directions that plant parts grow in. These directional movements are called tropic movement, it can be either towards the stimulus or away from it.
27. Name the part of the neuron where information is acquired.
Ans. Information, acquired at the end of the dendritic tip of a nerve cell that sets off a chemical reaction that creates an electrical impulse.
28. Name the part of the neuron through which the information travels as an electric impulse.
Ans. Axon is the part of the neuron through which the information travels as an electric impulse.
29. Name the mechanism by which the amount of hormones in the blood is regulated.
Ans. The amount of hormone released is regulated by feedback mechanisms.
30. Name two tissues that provide control and coordination in animals.
Ans. Two tissues that provide control and coordination in animals are nervous and muscular tissues.
31. Name the disease by which a person is likely to suffer due to the deficiency of Iodine and Insulin.
Ans. Goiter is the disease by which a person is likely to suffer due to the deficiency of Iodine and the symptom is a swollen neck.
32. Define phototropism.
Ans. The growth of a plant or other organism in response to light, either towards the source of light ( positive phototropism ) or away from it ( negative phototropism ) is called phototropism.
33. Name the largest cell present in the human body.
Ans. Nerve cell the largest cell present in the human body.
35. How does our body maintain blood sugar levels?
Ans. Insulin is a hormone that is produced by the pancreas and helps in regulating blood sugar levels.
II. Short answer type question:
(i) Metabolism of carbohydrates fats and proteins.
(ii) Balance of calcium and phosphate
(iii) Blood pressure
(iv) Water and electrolyte balance.
Ans. (i) Thyroxin hormone (produced by the thyroid gland).
(ii) The parathyroid hormone (produced by Parathyroid glands present in the neck behind the thyroid gland).
(iii) Aldosterone hormone (produced by adrenal glands).
(iv) Antidiuretic Hormone (released from the pituitary gland).
2. When a person is suffering from severe cold, he or she cannot differentiate the smell of perfume. Why?
Ans. The nose contains olfactory receptors that detect the smell. When a person is suffering from severe cold, the nose gets blocked so olfactory receptors cant detects any smell.
Ans. The nose contains olfactory receptors that detect the smell. When a person is suffering from severe cold, the nose gets blocked so olfactory receptors cant detects any smell.
3. What will happen if the intake of iodine in our diet is low?
Ans. If the intake of iodine in our diet is low, there is a possibility that we might suffer from goiter. One of the symptoms of this disease is a swollen neck.
Ans. If the intake of iodine in our diet is low, there is a possibility that we might suffer from goiter. One of the symptoms of this disease is a swollen neck.
4. What is tropic movement? Explain with an example.
Ans. Environmental triggers such as light, or gravity will change the directions that plant parts grow in. These directional movements are called tropic movement, it can be either towards the stimulus or away from it.
Example - The roots of a plant always grow downwards while the shoots usually grow upwards and away from the earth and this movement in response to gravity, which is geotropism.
Ans. Environmental triggers such as light, or gravity will change the directions that plant parts grow in. These directional movements are called tropic movement, it can be either towards the stimulus or away from it.
Example - The roots of a plant always grow downwards while the shoots usually grow upwards and away from the earth and this movement in response to gravity, which is geotropism.
5. What is reflex action ? Give two examples.
Ans. In some situations where we are responding with some action to changes in our environment without thinking about it or feeling in control of our reaction. This reaction is known as a reflex reaction.
Examples - (i) I pulled my hand back from the flame reflexly,
(ii) I was so hungry my mouth started watering reflexly.
Ans. In some situations where we are responding with some action to changes in our environment without thinking about it or feeling in control of our reaction. This reaction is known as a reflex reaction.
Examples - (i) I pulled my hand back from the flame reflexly,
(ii) I was so hungry my mouth started watering reflexly.
6. Explain the cause of shoots of the plant bending towards the light.
Ans. Phototropism is the cause of shoots of the plant bending towards the light which is a kind of phototropic movement in which plant parts grow towards the light.
Ans. Phototropism is the cause of shoots of the plant bending towards the light which is a kind of phototropic movement in which plant parts grow towards the light.
7. What are the nastic and curvature movements? Give one example of each.
Ans. Nastic Movements - It is non-directional movements that show response towards stimuli like light, temperature. The direction of nastic movements is independent of the direction of the stimulus.
Example - Opening and closing of flowers.
Ans. Nastic Movements - It is non-directional movements that show response towards stimuli like light, temperature. The direction of nastic movements is independent of the direction of the stimulus.
Example - Opening and closing of flowers.
Curvature Movements - This movement includes bending or curving of a plant in response to any stimuli.
Example - Curving of the stem tip (tendril) towards the light and curving of roots away from light.
Example - Curving of the stem tip (tendril) towards the light and curving of roots away from light.
8. Write the name and function of any two parts of the hind-brain.
Ans. Cerebellum and medulla are the two parts of the hind-brain.
Functions:
(i) Cerebellum - It controls voluntary actions like walking in a straight line, riding a bicycle, picking up a pencil and maintaining the posture and balance of the body.
(ii) Medulla - It controls involuntary actions like blood pressure, salivation, and vomiting.
Ans. Cerebellum and medulla are the two parts of the hind-brain.
Functions:
(i) Cerebellum - It controls voluntary actions like walking in a straight line, riding a bicycle, picking up a pencil and maintaining the posture and balance of the body.
(ii) Medulla - It controls involuntary actions like blood pressure, salivation, and vomiting.
9. Explain with the help of an example of how the timing and amount of hormones released regulated?
Ans. The timing and the amount of hormone released are regulated by feedback mechanisms.
For example - 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.
Ans. The timing and the amount of hormone released are regulated by feedback mechanisms.
For example - 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.
10. Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify the statement.
Ans. Control and coordination are the functions of the nervous system and hormones in our bodies.
The nervous system uses electrical impulses to transmit messages gets information from our sense organs and acts through our muscles.
Hormones produced by the hormonal system, in one part of an organism move to another part to achieve the desired effect. A feedback mechanism regulates the action of the hormone.
Ans. Control and coordination are the functions of the nervous system and hormones in our bodies.
The nervous system uses electrical impulses to transmit messages gets information from our sense organs and acts through our muscles.
Hormones produced by the hormonal system, in one part of an organism move to another part to achieve the desired effect. A feedback mechanism regulates the action of the hormone.
11. (i) Draw a well-labeled diagram of the human brain.
(ii) Which is the main thinking part of the brain?
Ans. (i) diagram
(ii) The brain has three major parts, namely the fore-brain, mid-brain, and hind-brain. Fore-brain is the main thinking part of the brain and it has regions that receive sensory impulses from various receptors.
Ans. (i) diagram
(ii) The brain has three major parts, namely the fore-brain, mid-brain, and hind-brain. Fore-brain is the main thinking part of the brain and it has regions that receive sensory impulses from various receptors.
12. Identify the gland that secretes (i) Insulin & (ii) Thyroxin.
Ans. (i) Pancrease secrets insulin hormone and helps in regulating blood sugar levels.
(ii) Thyroid gland secrets thyroxin.
Ans. (i) Pancrease secrets insulin hormone and helps in regulating blood sugar levels.
(ii) Thyroid gland secrets thyroxin.
13. Name the property that causes the tendrils to circle around the object. Explain how it happens and how the plan is benefited by it.
Ans. Thigmotropism is the causes the tendrils to circle around the objects.
Some plants like the pea plant climb up other plants or fences by means of tendrils. These 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 circle around the object and thus cling to it.
Ans. Thigmotropism is the causes the tendrils to circle around the objects.
Some plants like the pea plant climb up other plants or fences by means of tendrils. These 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 circle around the object and thus cling to it.
14. How does chemical coordination take place in animals?
Ans. Hormones help in chemical coordination in animals which is secreted by the endocrine gland. It is a chemical messenger that regulates the physiological processes in living organisms. The regulation of physiological processes, and control and coordination by hormones comes under the endocrine system.
15. How is the brain protected from injury and Shock? Name two main parts of the hindbrain and state the function of each.
Ans. The body is designed so that the brain sits inside a bony box. Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption.
cerebellum and medulla are the two main parts of the hind-brain.
The cerebellum controls voluntary action and medulla controls involuntary action.
Ans. The body is designed so that the brain sits inside a bony box. Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption.
cerebellum and medulla are the two main parts of the hind-brain.
The cerebellum controls voluntary action and medulla controls involuntary action.
16. Name a hormone secreted by the :
(i) Pancreas (ii) Pituitary (iii) Thyroid.
(i) Pancreas (ii) Pituitary (iii) Thyroid.
State one function of each of the hormones.
Ans. (i) Insulin secreted by the pancreas -Insulin helps in regulating blood sugar levels.
Ans. (i) Insulin secreted by the pancreas -Insulin helps in regulating blood sugar levels.
(ii) Growth hormone secreted by the pituitary gland - Regulates growth and development of the body
(iii) Thyroxin secreted by the thyroid gland - Provide the best balance for growth.
17. Define reflex action. Give one example. Show with the help of a flow diagram of the path of the reflex action.
Ans. Reflex action is a quick response (without thinking about it, or without feeling in control of our reactions) in situations where the organism does not have enough time to think.
Ans. Reflex action is a quick response (without thinking about it, or without feeling in control of our reactions) in situations where the organism does not have enough time to think.
18. How do auxins help in bending of the stem towards the light? Explain.
Ans. Auxin is a plant growth hormone. When growing plants detect light, auxin, synthesised at the shoot tip, 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 the light.
Ans. Auxin is a plant growth hormone. When growing plants detect light, auxin, synthesised at the shoot tip, 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 the light.
19. How do auxins promote the growth of a tendril around a support? Describe in brief.
Ans. Auxin is a plant growth hormone that is synthesized at the tip of the shoot. It helps the cell grow longer. When a tendril comes in contact with a support,
Ans. Auxin is a plant growth hormone that is synthesized at the tip of the shoot. It helps the cell grow longer. When a tendril comes in contact with a support,
auxin stimulates faster growth of the cells on the opposite side that's why the
tendril forms a coil around the support.
20. In the given diagram of reflex arc (i) Name the parts labeled A B C D and G (ii) Write the functions of C & B. 
Ans. (i) A - Receptor
B - effector
C- sensory nerve
G - Motor nerve
D - Relay neuron
(ii) C - carries impulse from receptor to spinal cord
B - Responds to stimulus.
21. Name the hormones that are secreted by our body to deal with scary situations. List any two responses shown by our body when these hormones are secreted into the blood.
Ans. Adrenaline hormones that are secreted from the adrenal glands to deal with scary situations.
i. It acts on the heart due to which the heart beats faster, resulting in the supply of more oxygen to our muscles.
ii. The blood to the digestive system and skin is reduced due to the contraction of muscles around small arteries in these organs.
Ans. Adrenaline hormones that are secreted from the adrenal glands to deal with scary situations.
i. It acts on the heart due to which the heart beats faster, resulting in the supply of more oxygen to our muscles.
ii. The blood to the digestive system and skin is reduced due to the contraction of muscles around small arteries in these organs.
22. Electrical impulses are an excellent mean of quick transfer of information in animals but there is a limitation to the use of electrical impulses. A list such as limitations. State the other means of communication used by most multicellular organisms between the cells.
Ans. Firstly, they will reach only those cells that are connected by nervous tissue.
Secondly, once an electrical impulse is generated in a cell and transmitted, the cell will take some time to reset its mechanisms before it can generate and transmit a new impulse.
It is thus no the wonder that most multicellular organisms use another means of communication between cells, namely, chemical communication.
Ans. Firstly, they will reach only those cells that are connected by nervous tissue.
Secondly, once an electrical impulse is generated in a cell and transmitted, the cell will take some time to reset its mechanisms before it can generate and transmit a new impulse.
It is thus no the wonder that most multicellular organisms use another means of communication between cells, namely, chemical communication.
23. Name the plant hormones responsible for the following:
(i) Elongation of cells (ii) Growth of steam(iii) Promotion of cell division(iv) Falling of sensors and leaves.
Ans. (i) Auxin
(ii) Gibberellins
(iii) Cytokinins
(iv) Abscisic acid.
Ans. (i) Auxin
(ii) Gibberellins
(iii) Cytokinins
(iv) Abscisic acid.
24. While watering a rose plant, a thorn pricked Rita's hand. How would she respond to this situation? Provide the term for such type of response.
Ans. When a thorn pricked Rita's hand, she will suddenly move away her hand. This type of response is known as a reflex action.
Ans. When a thorn pricked Rita's hand, she will suddenly move away her hand. This type of response is known as a reflex action.
25. State the role of the brain in a reflex action.
Ans. Reflex action is a quick response (without thinking about it, or without feeling in control of our reactions) in situations where the organism does not have enough time to think. Reflex arcs are formed in the spinal cord, although the information inputs also reach the brain.
Ans. Reflex action is a quick response (without thinking about it, or without feeling in control of our reactions) in situations where the organism does not have enough time to think. Reflex arcs are formed in the spinal cord, although the information inputs also reach the brain.
26. What happens at the synapse between two neurons?
Ans. At the end of the axon, the electrical impulse sets off the release of some chemicals and these chemicals cross the synapse and start an electrical impulse in a dendrite of the next neuron.
27. The gland secretes a particular hormone. The deficiency of this hormone in the body causes a particular disease in which the blood sugar level rises.
(i) Name the gland and the hormone secreted by it.
(ii) Mention the role played by this hormone.
(iii) Name the disease caused due to deficiency of this hormone.
Ans. (i) The gland is the pancreas that secrets insulin.
(ii) Insulin helps in regulating blood sugar levels.
(iii) Diabetes is the disease caused due to deficiency of this hormone insulin.
28. Brain and spinal cord are two vital organs of our body. How is our body designs to protect them?
Ans. The body is designed so that the brain sits inside a bony box. Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption.
If we run our hand down the middle of our back, we will feel a hard, bumpy structure. This is the vertebral column or backbone which protects the spinal cord.
29. (i) Name the part of the neuron where information is acquired.
(ii) Through which information travels as an electrical impulse.
Ans. (i) Information is acquired at the end of the dendritic tip of a nerve cell.
(ii) Information travels through axon as an electrical impulse.
III. Long answer type questions:
1. Mention one function of each of these hormones: Thyroxine, Insulin, Adrenaline, Growth hormones and Testosterone.
Ans. Thyroxin - regulates carbohydrate, protein, and fat metabolism in the body so as to provide the best balance for growth.
Ans. Thyroxin - regulates carbohydrate, protein, and fat metabolism in the body so as to provide the best balance for growth.
Insulin - helps in regulating blood sugar levels.
Adrenaline - helps in increasing the heart rate, increasing blood pressure, enlarging the pupil in the eye, diverts the blood to our skeletal muscles redistributing blood to the muscles and altering the body's metabolism, to maximise blood glucose levels.
Growth hormone - regulates growth and development of the body.
Testosterone - helps in the development of male reproductive tissues such as testes and prostate.
2. What are the major parts of the brain? Mention the function of different parts.
Ans. The brain has three major parts or regions, namely the fore-brain, mid-brain, and hind-brain.
Fore-brain is the main thinking part of the brain. It receives sensory impulses from various receptors. Forebrain controls body temperature, blood sugar, hunger, sensory signals. It also controls motor which controls the movement of voluntary muscles.
Mid-brain controls involuntary actions like mouth started watering reflexly, hearts beat without our thinking about it, change in the size of the pupil, and the thought out actions such as moving a chair, are controlled by the mid-brain.
Hind-brain controls involuntary actions including blood pressure, salivation, and vomiting, think about activities like walking in a straight line, riding a bicycle, picking up a pencil.
3. I. Answer the following :
(i) Name the endocrine glands associated with the brain.
(ii) Which gland secretes digestive enzymes as well as hormones?
(iii) Name the endocrine gland associated with Kidneys?
(iv) Which endocrine gland is represented in males but not in a female?
(ii) Which gland secretes digestive enzymes as well as hormones?
(iii) Name the endocrine gland associated with Kidneys?
(iv) Which endocrine gland is represented in males but not in a female?
II. List in tabular form the three differences in the movement of leaves of a touch-me-not plant when touched and movement of a tendril towards support.
Ans. I. (i) The pituitary gland and pineal gland are associated with the brain.
(ii) The pancreas secretes digestive enzymes as well as hormones.
(iii) The adrenal gland associated with Kidneys.
(iv) The testis gland is represented in males but not in a female.
II. (i) Movement in a touch-me-not plant is a non-directional movement whereas in a tendril movement is directional movement.
(ii) Movement in touch-me-not plant mostly exhibited by the leaf and flower petals whereas mostly stem and branch of plant sow movent like movent in a tendril.
(iii) The direction of movement in touch-me-not does not depend upon the direction of the stimulus whereas the direction of movement in a tendril is depended upon stimulus.
4. i. Name that hormone released by the thyroid gland. Also, write the function of this hormone. Give one of its symptoms.
I. A florist sprinkled a plant hormone to prevent wilting of leaves. Name the hormones he must have used.
Ans. I. Thyroxin hormone released by the thyroid gland.
Thyroxin regulates carbohydrate, protein, and fat metabolism in the body so as to provide the best balance for growth.
Iodine is essential for the synthesis of thyroxin. In the case of iodine is deficient in our diet, there is a possibility that we might suffer from goiter. One of the symptoms of this disease is a swollen neck.
II. A florist sprinkled a plant hormone called ethylene which helps in wilting of leaves and ripening of fruits. It also stimulates shoot and root growth.
5. Name the main thinking part of the human brain. List four major functions of this part.
Ans. Fore-brain is the main thinking part of the brain.
i. It receives sensory impulses from various receptors.
ii. Separate areas of the fore-brain are specialised for hearing, smell, sight and so on.
iii. In this part of the brain sensory information is interpreted by putting it together with information from other receptors as well as with information that is already stored in the brain.
iv. It controls body temperature, reproductive functions, eating, sleeping, and the display of emotions.
6. Name the plant hormones that promote growth. How do these hormones bring about phototropism in the shoot of a plant?
Ans. Two plant hormones are gibberellins and cytokinins that promote growth.
Gibberellins help in the growth of the stem and cytokinins promote cell division.
When growing plants detect light, a hormone called auxin, synthesized at the shoot tip, 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 the light.
7. What constituents the central and Peripheral nervous system? How are the components of the central nervous system protected?
Ans. The brain and the spinal cord constitute the central nervous system. They receive information from all parts of the body and integrate it.
The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system consisting of cranial nerves arising from the brain and spinal nerves arising from the spinal cord. The brain thus allows us to think and take actions based on that thinking.
Brain protected by the bony box. Inside the box, the brain is contained in a fluid-filled balloon which provides further shock absorption and the vertebral column or backbone which protects the spinal cord.
8. What is the function of the mid-brain? Name the three different parts of the hindbrain and give one function of each.
Ans. Our mouth waters when we see the food we like without our meaning to, our hearts beat without our thinking about it, change in the size of the pupil, and the thought out actions such as moving a chair, there is another set of muscle movements over which we do not have any thinking control. Many of these involuntary actions are controlled by the mid-brain.
Three parts of the hindbrain are medulla oblongata, pons and cerebellum.
Functions:
Involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla.
Activities like walking in a straight line, riding a bicycle, picking up a pencil. These are possible due to the cerebellum. It is also responsible for the precision of voluntary actions and maintaining the posture and balance of the body
Pons regulating the breathing rhythm, sleep, respiration, swallowing, bladder control, and hearing, etc.
9. I. Name two hormones secreted by the pancreas. Write one function of each hormone.
II. How does our body respond when adrenaline is secreted into the blood?
Write an example to explain the feedback mechanism for the regulation of hormone secretion.
Ans. I. Insulin and gastrin are the two hormones secreted by the pancreas.
Insulin helps in regulating blood sugar levels. If it is not secreted in proper amounts, the sugar level in the blood rises causing disease like diabetes.
II. Adrenaline is secreted directly into the blood from the adrenal glands and carried to different parts of the body. The target organs or the specific tissues on which it acts include the heart. As a result, the heart beats faster, resulting in the supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to the contraction of muscles around small arteries in these organs. This diverts the blood to our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles. All these responses together enable the animal body to be ready to deal with the situation.
Example of feedback mechanism for the regulation of hormone secretion.: 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.
10. (i) State the function of plant hormones.
(ii) Name a plant hormone if it is essential for cell division.
(iii) Name the hormone which is involved in photosynthesis. Explain its role.
(ii) Name a plant hormone if it is essential for cell division.
(iii) Name the hormone which is involved in photosynthesis. Explain its role.
Ans. (i) Plant hormones help to coordinate growth, development, and responses to the environment.
(ii) Cytokinins are a plant hormone that promotes cell division.
(iii) Auxin is the hormone that is involved in photosynthesis.
When growing plants detect light, auxin, synthesized at the shoot tip, 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 the light.
11. Name the hormone secreted by the thyroid gland and state its function. Why is it important for us to have or iodized salt in our diet? Name the disease caused due to the deficiency of iodine and mention its main symptoms.
Ans. Thyroxin hormone secreted by the thyroid gland and it regulates carbohydrate, protein, and fat metabolism in the body so as to provide the best balance for growth.
It is important for us to have or iodized salt in our diet because iodine is essential for the synthesis of thyroxin. In the case of iodine is deficient in our diet, there is a possibility that we might suffer from goiter.
The symptoms of this disease is a swollen neck.
12. (i) Name the parts of the brain which control voluntary action, involuntary action.
(ii) What is the significance of the peripheral nervous system?
(iii) Name the components of this nervous system and distinguish between the origins of the two.
Ans. (i) The brain has three major parts, namely the fore-brain, mid-brain and hind-brain which control voluntary and non-voluntary action.
Fore-brain is the main thinking part of the brain. Activities like walking in a straight line, riding a bicycle, picking up a pencil. These are possible due to a part of the hind-brain called the cerebellum.
Involuntary actions like blood pressure, salivation, vomiting, our mouth waters when we see the food we like without our meaning to, our hearts beat without our thinking about it, change in the size of the pupil are controlled by the medulla in the hind-brain.
(ii) The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system consisting of cranial nerve and spinal nerve.
Difference between the origins of the two - cranial nerves arising from the brain and spinal nerves arising from the spinal cord.
13. Name various plant hormones. Also, gives their physiological effect on plant growth and development.
Ans. Various plant hormons are auxin, gibberellins and cytokinins.
(i) Auxin - When growing plants detect light, a hormone called auxin, synthesized at the shoot tip, 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.
(ii) Gibberellins - Gibberellins help in the growth of the stem.
(iii) Cytokinins - Cytokinins promote cell division, and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds.
(iv) Abscisic acid - Plants also need signals to stop growing. Abscisic acid is one example of a hormone that inhibits growth. Its effects include wilting of leaves.
(ii) Gibberellins - Gibberellins help in the growth of the stem.
(iii) Cytokinins - Cytokinins promote cell division, and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds.
(iv) Abscisic acid - Plants also need signals to stop growing. Abscisic acid is one example of a hormone that inhibits growth. Its effects include wilting of leaves.
14. Draw and label the endocrine gland.
Ans.
15. Draw and label the part of the neuron. What is the function of the neuron?
Ans.
nervous tissue is made up of an organised network of nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.
16. Why is the flow of signals in a synapse from the axonal end of one neuron to the dendritic end of another neuron but not the reverse?
Ans. All information from our environment is detected by the specialised tips of some nerve cells called receptors. This information, acquired at the end of the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron. So the flow of signals in a synapse from the axonal end of one neuron to the dendritic end of another neuron but not the reverse.
17. (i) Which structure protects the spinal cord?
(ii) Write an activity to show phototropism and geotropism
(iii) What type of movement is shown by mimosa plant leaves when touched with a finger?
Ans. (i) The vertebral column or backbone protects the spinal cord.
(ii) (a) Fill a conical flask with water.
(b) Cover the neck of the flask with a wire mesh.
(c) Keep two or three freshly germinated beam seeds on the wire mesh.
(b) Cover the neck of the flask with a wire mesh.
(c) Keep two or three freshly germinated beam seeds on the wire mesh.
(d) Take a cardboard box that is open from one side.
(e) Keep the flash in the box in such a manner that the open side of the box faces light coming from a window.
(f) After two or three days, we will notice that the shoots bend towards light and roots away from light.
(g) Now turn the flask so that the shoots are away from light and the roots towards the light. Leave it undisturbed in this condition for a few days.
(iii) Nastic movement.
(e) Keep the flash in the box in such a manner that the open side of the box faces light coming from a window.
(f) After two or three days, we will notice that the shoots bend towards light and roots away from light.
(g) Now turn the flask so that the shoots are away from light and the roots towards the light. Leave it undisturbed in this condition for a few days.
(iii) Nastic movement.
18. Explain how the human body responds when adrenaline is secreted into the blood.
Ans.Adrenaline is secreted directly into the blood from the adrenal glands and carried to different parts of the body. Example the specific tissues on which it acts include the heart. Due to this the heart beats faster, resulting in the supply of more oxygen to our muscles. Due to the contraction of muscles around small arteries in these organs the blood to the digestive system and skin is reduced . This diverts the blood to our skeletal muscles. The rate of breathing increases because of the contractions of the diaphragm and the rib muscles. Due to all these responses together enable the animal body to be ready to deal with the situation.
Ans.Adrenaline is secreted directly into the blood from the adrenal glands and carried to different parts of the body. Example the specific tissues on which it acts include the heart. Due to this the heart beats faster, resulting in the supply of more oxygen to our muscles. Due to the contraction of muscles around small arteries in these organs the blood to the digestive system and skin is reduced . This diverts the blood to our skeletal muscles. The rate of breathing increases because of the contractions of the diaphragm and the rib muscles. Due to all these responses together enable the animal body to be ready to deal with the situation.
19. Mention one role of each of the following:
(i) Cerebellum for brain (ii) Medulla (iii) Forebrain.
Ans. (i) Activities like walking in a straight line, riding a bicycle, picking up a pencil, all are controlled by a part of the hind-brain called the cerebellum. It is also responsible for the precision of voluntary actions and maintaining the posture and balance of the body.
(ii) Involuntary actions like our mouth waters when we see food, blood pressure, change in the size of the pupil, salivation, and vomiting are controlled by the medulla in the hind-brain.
(iii) Fore-brain is the main thinking part of the brain. It receives sensory impulses from various receptors. Forebrain controls body temperature, blood sugar, hunger, sensory signals. It also controls motor which controls the movement of voluntary muscles,
(i) Cerebellum for brain (ii) Medulla (iii) Forebrain.
Ans. (i) Activities like walking in a straight line, riding a bicycle, picking up a pencil, all are controlled by a part of the hind-brain called the cerebellum. It is also responsible for the precision of voluntary actions and maintaining the posture and balance of the body.
(ii) Involuntary actions like our mouth waters when we see food, blood pressure, change in the size of the pupil, salivation, and vomiting are controlled by the medulla in the hind-brain.
(iii) Fore-brain is the main thinking part of the brain. It receives sensory impulses from various receptors. Forebrain controls body temperature, blood sugar, hunger, sensory signals. It also controls motor which controls the movement of voluntary muscles,
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