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Control and Coordination - Class 10 Science Textbook Solutions

 Control and Coordination

Control and Coordination Class 10 Extra s with Answers Science Chapter 7

1. Mention the receptors for light and sound in animals.
Sense organs are called receptors. The receptor of light in animals is calld photoreceptor. The receptor of sound in animals is called phonoreceptor.

2. Which hormone regulates the concentration of sugar in the blood?
Insulin secreted by Islets of Langerhans of pancreas.

3. Define ‘reflex action.’
Reflex action is a rapid, automatic response to a stimulus which is not under the voluntary control of the brain.

4. Name few involuntary actions controlled by the hindbrain.
Involuntary actions controlled by hindbrain are vomiting, salivation and blood pressure.

5. hat is an axon?
It is a large, single, unbranched nerve fibre arising from the cyton. It carries impulses from cyton located in CNS to effectors.

6. Why are roots called positively geotropic?
This is because the roots always grow towards the gravity of the Earth.

7. What is the number of cranial nerves and spinal nerves in human beings?
: There are 12 pairs of cranial nerves and 31 pairs of spinal nerves in human beings. 


8. Name the largest cell present in the human body.’
: Neuron.

9. Which part of central nervous system controls reflexes?
Spinal cord.

10. Name the part of neuron
(i) Where information is acquired.
(ii) Through which information travels as an electrical impulse.

(i) Dendrite,
(ii) Axon.

11. What will happen if intake of iodine in our diet is low?

•    When iodine intake is low, release of thyroxine from thyroid gland will be less by which protein, carbohydrate and fat metabolisms will be affected.
•    A person might suffer from goitre in case of iodine deficiency in the body.

12. Which hormone controls the metabolism of calcium and phosphorus in human beings?
Parathyroid hormone (parathormone).

13. Name the hormone, the secretion of which is responsible for dramatic changes in appearance in girls and boys when they approach 10-12 years of age.
Oestrogen from the ovaries of girls and testosterone from testes of boys.

14. Name two tissues that provide control and coordination in multicellular animals.
The two tissues that provide control and coordination in multicellular animals are nervous tissue and muscular tissue.

15. Draw a well labelled diagram of Neuron cell.
cell is shown in the following diagram.


16. What do you understand by the sleep movement of plant organs?
Sleep movement in plants e.g., in flowers is to protect the reproductive organs from the cold. Hence, sepals and petals of saffron flower close at sunset and open up in the morning.

17. State the main function of abscistic acid in plants. Answer: Abscisic acid slows plant growth and inhibits division of cells.’  18. What is spinal cord? Which body function is controlled by it? (U. P. 2018)
Spinal cord is a long and cylindrical tube which is present in vertebral column. From its dorsal  and ventral horn sensory and motor nerves originate which form spinal nerve. At the centre it contains neurocoel. Spinal cord is covered externally by three membranes. In this, H shaped grey matter is filled, which is surrounded by white matter. Lateral and dorsal sides have horns.
Spinal cord: It serves as principal centre for almost all the reflexes and involuntary activities. It provide conduction pathway for nerves to transmit stimuli to brain.

Control and Coordination Extra s Short Answer Type


 1. Define a synapse.
Synapse is a very fine gap between telodendria of axon of one neuron and dendrites of another neuron. These two structures do not unite with each other but remain separated by a fine gap.

2.Mention the functions of forebrain.
The forebrain performs the following functions:
•    It is responsible for intelligence, memory, consciousness, will power and voluntary actions.
•    It has the centres for visual reception, hearing reception, touch, smell and temperature reception.

3. 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?

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

4. Name the hormones responsible for regulation of
1.    metabolism of carbohydrates, fats and proteins
2.    balance of calcium and phosphate
3.    blood pressure
4.    water and electrolyte balance.

1.    Thyroxine
2.    Parathormone
3.    Adrenaline
4.    Vasopressin.

5. What is a tropic movement? Explain with an example.
The directional growth movement of plants due to external stimuli is called a tropic movement. It can be either towards the stimulus, or away from it. For example, in case of phototropic movement, shoots respond by bending towards light while roots respond by bending away from it.

6. Why Mimosa pudica (touch-me-not) leaves droop down when touched?
It is due to turgor pressure difference between the upper and lower halves of the base of petiole (pulvinus). Lower half cells lose water and upper half cells of pulvinus become turgid due to transfer of water from lower cells. Thus, the entire leaf droops down when touched.

7. Why are the electrical-chemical signals not an efficient means of communication in plants?
Unlike animals, where there is a nervous system for conduction of nerve impulses and circulatory system for conduction of hormones, there are no specialised tissues in plants. So, the electrical chemical signals are not an effective means of communication in plants.

8.If a ripened fruit is kept in a basket of raw fruits, then what will happen? What causes it?
The  fruit will release ethylene (hormone) which causes ripening of other raw. fruits kept in a basket.

9. What is cerebrospinal fluid? What is its function? .
Cerebrospinal fluid is the fluid found in the cavities of brain and central canal of spinal cord and in between arachnoid and pia mater.
Function: It prevents the brain and spinal cord from mechanical shocks.

10. Answer the following:
1.    Name the endocrine gland associated with a brain.
2.    Which gland secretes digestive enzymes as well as hormones?
3.    Name the endocrine gland associated with kidneys.
4.    Which endocrine gland is present in males but not in females?

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

11. Describe the advantage of division of human heart in right and left parts.
The advantage of division of human heart in right and left parts is that it prevents mixing of oxygenated and deoxygenated blood.

12. How do animal muscles move?
The nerve fibrés at the end of a neuron are attached to muscles. This area is called neuro-muscular junction. When nerve impulses are conducted to this area, the special proteins present in the muscle cells change their shape and arrangement in the cell in response to nervous electrical impulses. New arrangement of these proteins give the muscle cells a shorter form thus bringing about movement of muscles.

13. What is turgor movement?
Turgor movement is the movement due to the difference of turgidity of the cells in the lower half and upper half of pulvinus (petiole of leaf). When leaf of touch-me-not plant (Mimosa pudica) is touched, the electrical signal send chemical signals from leaflets to pulvinus (petiole) of leaf. Cells in the lower half of pulvinus lose water and become flaccid, while cells in the upper half of pulvinus become turgid due to accumulation of more water. Hence, leaf droops down for a short time.

14. Why do tendrils coil around hard rough objects?
The growth movement of tendril in response to unilateral stimulus of touch is called thigmotropism. Tendrils of louki, tori, karela, and sweet pea plants coil around hard objects when they come in their contact. It occurs due to unequal growth of two sides of a tendril. The growth of the surface which comes in contact of the support is retarded, while it remains normal or increased on the other side, due to which tendril coils around the support.

15. How are involuntary actions and reflex actions different from each other?


16. Nervous and hormonal system together perform the function of control and coordination in human beings. Justify the statement.
Nervous and hormonal system together perform the function of control and coordination in human beings. Let us take an example, in the case of any emergency, stimulus is being perceived by CNS (Central nervous system). The stimulus is analysed and the response is sent to the effectors. Simultaneously, sympathetic nerves stimulate adrenal gland to release adrenaline which regulates blood pressure, increases heartbeat, constricts blood vessels and dilates pupil, etc. So, both nervous and endocrine systems interact and overcome the crisis together.

17. How are the brain and spinal cord protected?

(i) Brain: It is protected by the bony box called cranium. It is also called as skull. Also the membranes that surround the brain (meninges) are filled with cerebrospinal fluid that act as shock absorbers protecting the brain.
(ii) Spinal cord: The vertebral column, commonly called backbone, protects the spinal cord.

18. What are ductless glands?
: These ductless glands which form a group of tissues or cells in acting at distant sites of the body known as target organ or target cell.

19. Name the hormone secreted by thyroid gland and describe its main functions.
The glands which secrete hormones directly into blood are called ductless or endocrine glands. They reach their target cells through blood only and not through any duct. Thyroid gland is a bilobed structure situated at posterior surface of larynx. Its structure resembles ‘H’. Its weight in humans is about 25-30 g.
It mainly releases thyroxine or thyroid hormone which is a product of iodine. This hormone regulates metabolic activities in body. Its functions are to control the BMR rate, protein synthesis, increase heartbeat rate, uses of glucose. Lack of thyroid causes slowing of heartbeat, weak immune system and brain damage.

20. What are hormones and enzymes? Mention any two differences between them.
The differences between hormones and enzymes are as follows:

Control and Coordination Extra s Long Answer Type

1. Which hormone is released into the blood when its sugar level rises? Name the organ which produces the hormone and describe its effect on blood sugar level. Also name one digestive enzyme that this organ secretes and the function of this enzyme.
Hormone: Hormones are released by stimulated cells are diffuse all around the original cell. Insulin hormone is released into the blood when its sugar level rises. Pancreas secretes the insulin hormone. The function of insulin hormone is to lower the blood sugar level.
Deficiency of insulin hormone in the body causes a disease known as diabetes. Diabetes is characterised by large quantities of sugar in the blood. The insulin hormone controls the metabolism of sugar. If due to some reason pancreas does not produce and secrete sufficient amount of insulin into blood.
then the sugar level in the blood rises. The high sugar level in the blood can cause many harmful effects to the body of person. The person having severe diabetes are treated by giving injection of insulin.
The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins, lipase for breakdown of emulsified fats and amylase for breakdown of starch.

2. Differentiate between tropic and nastic movements in plants.


(i) What are cranial and spinal nerves? Describe a spinal nerve. 

(ii) Draw a diagram of the human brain and label the following parts: (a) Cerebrum (b) Meninges (c) Medulla oblongata (d) Cerebellum

(i) Cranial nerves are the nerves associated with the brain. These are 12 pairs in number and carries both sensory and motor nerves. Spinal nerves are the nerves connected with the spinal cord. These are 31 pairs in number. Spinal nerve arises in the form of dorsal root and ventral root and both unite in the neural canal to form a single branch. It comes out of the vertebral column through intervertebral canal and then divides into dorsal, ventral and visceral branches.


4. Describe the central nervous system in human beings.
How many parts of brain are there? Sodden reactions like blood pressure, saliva secretion and vomating are controlled by which parts?
The central nervous system in human beings consists of brain and spinal cord.
(i) Brain: Brain is the highest coordinating centre in the body. It is covered by meaninges, which is made up of three layers. It is protected by cranium. Brain is broadly divided into:
(a) Forebrain: The forebrain includes cerebrum and olfactory lobes. Cerebrum is the largest part of the brain. It consists of two cerebral hemispheres. Sensory and motor receptors are present in the brain. There are various regions for reception of vision (occipital lobe), reception of sound (temporal lobe), touch, smell, temperature (parietal lobe) and muscular activities (frontal lobe). Olfactory lobes are one in pair and receives olfactory nerves.
(b) Midbrain: It is the small portion of the brian that connects cerebrum with the other parts of the brain and spinal cord.
(c) Hindbrain: It consists of cerebellum, pons and medulla oblongata. Cerebellum is responsible for coordination and adjustment of movement and posture. Pons regulate respiration. Medulla oblongata regulates swallowing, coughing, sneezing and vomitting…
(ii) Spinal cord: Medulla oblongata extends downwards, enclosed in vertebral column to form a cylindrical structure known as spinal cord. It is also covered by meninges. It is the reflex centre of the body.

5. Give the various functions performed by the plant hormones.
Name various plant hormones. Also give their physiological effects on plant growth and development.

The various functions performed by the plant hormones are:
(i) Auxins promote cell enlargement and cell differentiation. They also promote growth.
(ii) Gibberellins promote cell enlargement and cell differentiation in the presence of auxin. It also help in breaking the dormancy in seeds and buds. It promote the growth in fruits.
(iii) Cytokinins promote cell division and help in breaking the dormancy of seeds and buds. It delay the ageing in leaves. It promotes the opening of stomata and also fruit growth.
(iv) Abscisic acid promotes the dormancy in seeds and buds. It promotes the closing of stomata and falling of leaves. It also inhibits growth, reverses the growth promoting effects of auxins and gibberellins. Its effects include wilting of leaves.
(v) Ethylene promotes the falling of leaves, ripening of fruits and helps in breaking bud dormancy.

6. What is reflex action? Explain with the help of examples.
What are reflex actions? Give two examples. Explain a reflex are.
A reflex action is defined as a spontaneous, automatic and mechanical response to a stimuli without the will of an individual. In such actions there is no involvement of the brain. All reflex actions are conveyed through the spinal cord by a path called reflex arc.
The reflex action travels in the following sequence:

The reflex arc consitute the following components:
1.    A receptor to perceive the stimulus.
2.    A sensory or afferent nerve which carries the message from the receptor to the spinal cord.
3.    The neurons of spinal cord transmit the impulse from afferent neurons to efferent neurons.
4.    The motor or efferent nerve carries messages from spinal cord to the muscles (effectors) that show the response.
Some examples of reflex actions are:
1.    Blinking of eyes when a foreign particle gets in them.
2.    Sneezing if an unwanted particle enters the nose.
3.    Watering of mouth at the sight or smell of good food.
4.    Withdrawl of foot if a nail comes in the way while walking and pricks the foot.
5.    Immediate withdrawl of hand on touching some hot thing.

7. With the help of an activity demonstrate geotropism in plants.


1.    Soak some seeds of gram or moong in water for one day.
2.    Pierce slightly big holes (2 mm diameter) at the bottom of the cup.
3.    Fill it with 1 cm. thick layer of garden soil.
4.    Sprinkle soaked seeds (moong / gram) over the soil. Water the seeds.
5.    Put the cup on 2 pieces of wooden or stone slabs so that there is a little gap between the top of the table and bottom of the cup.
6.    Cover the lower part of the set-up with black paper.
7.    Water the seeds regularly with little water.
8.    You will observe that the roots come out from the holes and grow towards the Earth showing positive geotropism.

8. Draw a well-labelled diagram of human brain and explain the functions of various parts.

Structure and functions of human brain: It is the most important and delicate portion of the body. In an adult, its weight is 1300-1400 g. It remains enclosed in bony case called cranium. The brain is covered with three meninges. The outer meninx is called duramater and inner one is piamater.
In between these two arachnoid matter is present. A dense network of blood capillaries present in these meninges, which provide food and oxygen to the brain. In between the meninges, the space is filled with cerebrospinal fluid (80%) which protects the brain against external shocks and mechanical injury.
1. Forebrain: The brain is divided into three parts-olfactory lobes, cerebrum and diencephalon. Cerebrum is the largest part of the brain. It is highly folded and convoluted which increases the surface area. The outer part of cerebrum is made up of grey matter while inner is made up of white matter. Cerebrum controls various activities of the body.
Parts of Forebrain
•    Olfactory lobes: These are concerned with sense of smell.
•    Cerebrum: It is the centre of instinct thinking, memorising, reasoning, consciousness, learning, etc.
•    Diencephalon: It is the centre of involuntary actions such as hunger, thirst, sleep, temperature, control, metabolism, etc.
2. Midbrain: It connect forebrain to hindbrains, many involuntary actions like change in size of pupil and auditory impulses are controlled by it.
3. Hindbrain: It consists of cerebellum, medulla oblongata and pons varolii.
(i) Pons varolii: It is situated just below of cerebral peduncles like a lobe of 2.5 cm long. It provides control of activities like mastication, salivation, lacrimation and movement of eyeballs, etc.
(ii) Cerebellum: It controls the body posture and equilibrium. It controls and coordinates the movement of voluntary muscles.
(iii) Medulla oblongata: It is the posterior’most part of the brain which is cylindrical in shape. It controls involuntary activities such as respiration, heartbeat, circulation etc.

9. What do you know about reflex action? Explain with the help of diagram. What is the importance of reflex actions?

Reflex action The path followed by information or impulse in reflex action is called reflex arc. It is formed in the spinal cord and consists of two neurons:
•    Sensory neurons containing dorsal horn.
•    Motor neurons containing ventral horn.
Sensory nerves pick up impulses from sense organs and bring them to spinal cord. As a result of which motor nerves take the message from spinal cord to the concerned effector orgAnswer: This response is called reflex action and this pathway is called reflex arc.

Importance: Reflex actions are very important, which have the following importances:
•    These are controlled by spinal cord and thus, minimise the burden on brain.
•    These are very fast and accurate, wich minimise chances of mishappening.
Some examples of reflex actions:
•    Sneezing: During this, the air from the lungs comes out forcefully.
•    Coughing: When food particles enter the windpipe the air from the lungs comes out forcefully.

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