RBSE Class 10 Science Important Questions Chapter 7 Control and Coordination

Rajasthan Board RBSE Class 10 Science Important Questions Chapter 7 Control and Coordination Important Questions and Answers.

RBSE Class 10 Science Chapter 7 Important Questions Control and Coordination

Objective Type Questions

Question 1.
What we call the small finer thread like branches coming out from nerve cell?
(a) Dendrite
(b) Synapse
(c) Rainwear
(d) Axon
Answer:
(a) Dendrite

Question 2.
Coordination in body is done by –
(a) Blood circulatory system
(b) Nervous system.
(c) Endocrine system
(d) Nervous system and endocrine system
Answer:
(d) Nervous system and endocrine system

Question 3.
Peripheral nervous system consists –
(a) Cranial and spinal nerves
(b) Brain and spinal cord
(c) Sympathetic nerves and parasympathetic
(d) Medulated nerves and non-medulated
Answer:
(a) Cranial and spinal nerves

Question 4.
The growth of pollen tube towards ovary is the movement –
(a) Geotropism
(b) Phototropism
(c) Hydrotropism
(d) Chemotropism
Answer:
(d) Chemotropism

Question 5.
Tendrils of pea coil around the support, this is a good example –
(a) Nastic movements
(b) Chemotropism
(c) Thigmotropism
(d) Phototropism
Answer:
(c) Thigmotropism

Question 6.
Leaves of sensitive plant (Mimosa pudica) droop as soon as they are touched, why?
(a) Injury in leaf tissue
(b) Nervous system in plants
(c) Leaves are delicate
(d) Change in turgid pressure at leaf base
Answer:
(d) Change in turgid pressure at leaf base

Question 7.
In following which effects the wilting of leaves –
(a) Abscisic acid
(b) Auxin
(c) Cytokinin
(d) Gibberellin
Answer:
(a) Abscisic acid

Question 8.
In following which hormone concentration is more in fruit and seeds?
(a) Cytokinin
(b) Auxin
(c) Gibberellin
(d) Abscisic acid
Answer:
(a) Cytokinin

Very Short Answer Type Questions

Question 1.
Which is main plant hormone which induces the cell division?
Answer: Cytokinins.

Question 2.
Which is the main coordinating centre of human body?
Answer:
Brain is the main coordinating centre of human body.

Question 3.
What is the main function of central nervous system ?
Answer:
They receive information from all parts of the body and integrate it.

Question 4.
Define reflex action and write one example.
Answer:
A reflex action is a fast automatic response to stimulus. Example—in strong light suddenly closing of eyes.

Question 5.
What will be the effect on glucose level in deficiency of insulin hormone in blood?
Answer:
The level of glucose will increase, diabetes disease may develop.

Question 6.
Which hormone control the sugar level in blood?
Answer:
Insulin hormone.

Question 7.
Which gland is endocrine and exocrine both found in human body?
Answer:
Pancreas.

Question 8.
What is the name of that part of the hind brain which control respiration?
Answer:
Medulla oblongata.

Question 9.
Write the name of two such movements, which is not related to growth.
Answer:

• Buffaloes chew cud
• a running cat.

Question 10.
Write the name of any two sense organs found in our body.
Answer:

• Nose
• Tongue.

Question 11.
Which nervous system is formed by combining brain and spinal cord.
Answer:
Brain and spinal cord combined form central nervous system.

Question 12.
What is the name of nerves coming out from brain?
Answer:
Cranial nerves are the nerves coming out from brain.

Question 13.
Write the three parts of brain.
Answer:

• Fore brain
• Mid brain
• Hind brain.

Question 14.
What type of movement does plant show ?
Answer:
Plant show two different types of movement – One dependent on growth and the other independent of growth.

Question 15.
Give one example in which movement in plant is independent of growth.
Answer:
Touch sensitive movement in the leaves of ‘touch-me-not’ or Mimosa plant.

Question 16.
How hormones are transmitted in Plants ?
Answer:
In plants, hormones simply diffuse to the area of action.

Question 17.
In which part of the stem auxin hormone is synthesized?
Answer:
Auxin hormones synthesized in apical part (tip) of the stem.

Question 18.
Which growth is controlled by plant hormones?
Answer:
Plant hormones control the directional growth.

Question 19.
Write the name of largest endocrine gland of body.
Answer:
Thyroid gland is the largest endocrine gland of the body.

Question 20.
Which recepter organ is related to equilibrium?
Answer:
Internal ear is related to equilibrium.

Question 21.
Which is the main thinking part of the brain?
Answer:
The fore-brain is the main thinking part of the brain.

Question 22.
How muscle cell move?
Answer:
Some muscle cell change shape in order for movement is happen.

Question 23.
How muscle cell change their shape ?
Answer:
A specialised protein is found in animal muscle cell which help them in changing shape.

Question 24.
Write the function of Hypo- thalanus hormone.
Answer:
It stimulates the pituitary gland to release growth hormone.

Question 25.
By which hormone in male secondary sexual characters formed?
Answer:
Testosterone hormone develop the secondary sexual characters in male.

Question 26.
What is nervous system?
Answer:
The organ-system of an organism which regulate and control the all inner functional systems of body is called nervous system.

Question 27.
What are the sensory organs? Give any one example.
Answer:
Sensory organs are those which identify the changes takes place in outer environment. Ex. eye, nose and ear.

Question 28.
Axon terminal of one neuron are connected to dendron of the next neuron, what is the name of gap present in between them?
Answer:
Synapse

Question 29.
Who protect the spinal cord?
Answer:
Vertebral column protect the spinal cord.

Short Answer Type Questions

Question 1.
What is the general scheme for nervous impulses travel in the body?
Answer:
All information from our environment is detected by the specialised tips of some nerve cells and sets off a chemical reaction that creates an electric impulse. This impulse travels from the dentrite 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 electric impulse in the dendrite of the next neuron. This is a general scheme of how nervous impulses travel in the body.

Question 2.
What is the reason of dwarfism in human?
Answer:
Lack of growth hormone secreted by pituitary gland develop dwarfism in human. Growth hormone control the growth of muscles and tissues in our body. Lack of it during childhood stops growth and affected person remains short in height.

Question 3.
What is the difference between phototropism and geotropism?
Answer:
The movement of plant shoot system towards the direction of light is called phototropism while movement of any part of the plant towards gravity of earth or its opposite direction is called geotropism. For example stem move towards upperside and root grow downwards.

Question 4.
How does our body get to know about the changes occurring in environment?
Answer:
All information from our environ-ment is detected by the specialised tips of some nerve cells. These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on. So gustatory receptors will detect taste while affactory receptors will detect smell.

Question 5.
Write one-one example of phototropism, geotropism, hydrotropism and chemotropism in plants.
Answer:

• Phototropism: Shoot system of plant curve in direction of light.
• Geotropism: Plant root growth downwards (towards earth).
• Hydrotropism: Movement of amoeba towards water,
• Chemotropism: Growth of pollen tube towards ovule.

Question 6.
Why pituitary gland is called master gland?
Answer:
Pituitary gland is present just below the hypothalamus of brain. It is pea seed size. This gland secretes approximate 13 types of hormones, which control different activities of our body. Collectively these hormones are called ‘Pituiterine hormone’. Some hormones secreted by this gland regulate the other endocrine glands of our body. Due to this reason this gland is called ‘master gland’.

Question 7.
Write the name of any three plant hormone and mention one function of each.
Answer:
Name of three hormones and their functions are as under –

• Auxin hormone: It is a growth hormone and it helps the cell to grow longer.
• Gibberellin hormone: It is also a growth hormone. It increase the length of stem.
• Abscisic acid: It inhibits growth. Its effects include writting of leaves.

Question 8.
Why reflex arc evolved in animals? Explain.
Answer:
Reflex arcs have evolved in animals because the thinking process of the brain is not fast enough. In fact many animals have very little or none of the complex neuron network needed for thinking. So it is quite likely that reflex arcs have evolved as efficient ways of functioning in the absence of true thought processes. However, even after complex neuron networks have come into existence, reflex arcs continue to be more efficient for quick responses.

Question 9.
What is peripheral nervous system?
Answer:
The system which is formed combindly by cranial nerves and spinal nerves, called peripheral nervous system.
1. Cranial nerves: The nerves which comes out from the brain of human, called cranial canals. In human there are 12 pair of cranial nerves. From these some cranial nerves are sensory, some motor and some are mixed.
2. Spinal nerves: The nerves come out from spinal cord called spinal nerves. There are 31 pairs of spinal nerves in human. All the spinal nerves are mixed type.

Question 10.
How voluntary actions are controlled? Explain.
Or
Explain the work of fore-brain ?
Answer:
The fore-brain is the main thinking part of the brain. It has regions which receive sensory impulses from various receptors. Separate areas of the fore-brain are specialised for hearing, smell, sight and so on. There are separate areas of ‘association where this 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. Based on all these, a decision is made about how to respond and the information is passed on to the motor areas which control the movement of voluntary muscles.

Question 11.
Write the differences in hormone and enzyme.
Answer:
Differences in hormone and enzyme

Hormone	Enzyme
1.Hormone activate or restrict any reaction.	1. They work as a catalyst in any reaction.
2. Hormones are Protein, Fatty acid, Tyrosine like in nature.	2. All enzymes are made up of Protein.
3. The molecular weight of hormone is less and molecules are small.	3. Molecules are large and molecular weight of enzyme is also more.
4. Hormones degraded in chemical reactions so again can not take parts.	4. They did  not degrade and again can take part.
5. They transported by blood.	5. Transported by tubes.
6. Hormones secreted by endocrine glands. They are synthesized at places away from where they act.	6. Enzymes are found in secretion of ectocrine glands and their functional place is nearer.
7. They can not be stored in body.	7. They can be stored for some time.

Question 12.
Mention the types of nerves on the basis of function.
Answer:
On the basis of function the nerves are of three types –

1. Sensory nerves: Such nerves which carry the nervous impulse to sensory organs than to brain, called sensory nerves.
2. Motor nerves: Such nerves which carry the nerve impulses from brain or spinal cord to effector organs, called motor nerves.
3. Mixed nerves: Such nerves which work both sensory as well as motor that means carry sensation towards brain and brain to muscles, called mixed nerves.

Question 13.
What are the limitations to the use of electrical impulses as a medium of information transfer in body ?
Answer:
1. They will reach only those cells that are connected by nervous tissue, not each and every cell in the animal body.
2. Once an electrical 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. In other words, cells cannot continually create and transmit electrical impulses.

Question 14.
Give five examples of reflex actions.
Answer:
Examples of reflex action –

• On hearing the sudden loud sound opened mouth.
• Shrinking in cold.
• Sneezing and coughing.
• Salivation of mouth on looking the good food.
• Construction of eyes on sudden bright light.

Question 15.
What will be the effect on destroying the cerebellum of human?
Answer:
Human cerebellum is the second largest part of the brain. It establish the coordination for voluntary movement in essential muscles. By complete contraction of cranial muscles make easy for walking, running, writing etc. activities. It helps in keeping the balance of body and maintain the equilibrium.
If cerebellum destroyed then there would be no coordination of voluntary muscles and by this there would be no regulation of voluntary muscle. In the result the movements of body would be uncontrolled.

Question 16.
Apart from electrical impulse, how information is transmitted in body ? Explain.
Or
Explain the process of chemical trans-mission in organisms.
Answer:
If, instead of generating an electrical impulse, stimulated cells release a chemical compound, this compound would diffuse all around the original cell. If other cells around have the means to detect this compound using special molecules on their surfaces, then they would be able to recognise information, and even transmit it. This will be slower of course, but it can potentially reach all cells of the body, regardless of the nervous connections, and it can be done steadily and persistently.

Question 17.
Write the difference between endocrine and exocrine gland.
Answer:
Difference in endocrine and exocrine glands.

Endocrine glands	Exocrine glands
1. These glands discharge their secretions directly into the blood.	1. Discharge their secretions into the ducts.
2. Secretions are called hormones.	2. Secretions are called enzymes.
3. These are ductless glands.	3. Glands with ducts.
4. They are responsible for proper growth and unctions of special organs. Example – Pituitary gland, Thyroid gland, Adrenal gland.	4. They are perfect in working on food and external materials. Example – Sweet glands, Milk glands.

Question 18.
If thyroid gland removed from a mammal, then which effects will be shown?
Answer:
Thryoid regulates carbohydrate, protein and fat metabolism in the body and induces the process of formation of mitochondria in cells. It also control the growth of the body and rate of heart beat. So on removal of thyroid gland from body, the above mentioned activities will not happen and deficiency of thyroxine hormone will develope the goitre, hashimoto diaseases.

Question 19.
How does the nervous tissue cause action? Explain.
Or
Explain the process of movement of muscle cell.
Answer:
Nervous tissue collects information, sends it around the body, processes information, makes decisions based on information, and conveys decisions to muscles for actions. When a nerve impulse reaches the muscle, the muscle fibre move. Muscle cells have special proteins that change both their shape and their arrangement in the cell in response to nervous electrical impulses. When this happens, new arrangements of these proteins give the muscle cells a shorter form.

Question 20.
During exciting or tension time which hormone amount increases in blood? Describe the changes in the body due to excess secretion of this hormone.
Answer:
At the time of exciting or tension the amount of adrenaline or epinephrine increases which is secreted by medulla of adrenal gland., This hormone prepare to organism to face the trouble in emergency conditions.
The following are the changes takes place in body due to excess secretion—

1. Increase in rate of heart beat, blood pressure and basal metabolism rate.
2. Erecting gooseflesh.
3. Dilation of eye pupils.
4. Reduction in blood clotting time.
5. Relaxing of trachea and bronchi muscles.
6. Increase in cardiac output.
7. Less blood flow in skin and more in muscles.

Special: There is more secretion of this hormone at the time of fight, flight and fear and prepare the organism to face for unfavourable condition. So this hormone is called 3F = FFF or this gland is known as FFF gland.

Question 21.
Write four functions of male hormone (Testosterone) found in human.
Answer:
Four functions of male hormone (Testosterone) –

1. This hormone is responsible for the development of secondary sexual characters in males like moustache, beard, low pitch (deeper) voice, development of strong muscles and bones.
2. It is helpful in spermatogenesis.
3. This hormone induces the male puberty.
4. This hormone effect on skin of male individual, by this skin becomes strong and red in colour.

Question 22.
There is no nervous tissue nor any muscle tissue in plants then how does the plant detect the touch and how do the leaves move in response?
Or
Explain the movement that happen is ‘touch-me-not’ plant?
Answer:
Since no growth is involved, the ‘touch-me-not’ plant must actually move its leaves in response to touch. Where exactly the plant is touched, and what part of the plant actually moves, it is apparent that movement happens at a point different from the point of touch. So, information that a touch has occurred must be communicated. The plants also use electrical-chemical means to convey this information from cell- to-cell, but unlike in animals, there is no specialised tissue in plants for the conduction of information.

Finally, again as in animals, some cells must change shape in order for movement to happen. Instead of the specialised proteins found in animal muscle cells, plant cells change shape by changing the amount of water in them, resulting in swelling or shrinking, and therefore in changing shapes.

Question 23.
For making the dense bushes of henna, gardner cut the apical portion of branches, why?
Answer:
In plants the apical bud Of main stem suppresses the growth of lateral buds. This condition is called apical dominance. For the purpose of right growth of lateral buds gardner cut the apical bud. Due to this bushes becomes dense.

Question 24.
What is growth inhibitor substances? Write the functions of growth inhibitor.
Answer:
Growth inhibitor substances –
Plant growth hormones induces the growth of plants but there are some chemicals or substances which inhibit the growth. Such substances are called growth inhibitor. Although ethylene help in ripening the fruit it works as growth inhibitor. Abscisic acid is also a growth inhibitor. This acid naturally found in plants. This is also called stress hormone.
Functions of Abscisic acid –

1. It developes abscission in leaves.
2. It enhance the dormant period of buds and seeds.
3. It developes senescence in leaves.
4. Inhibit flowering but helpful in formation of tuber in potato.
5. It inhibit both cell division and cell enlargement.
6. Inhibit the synthesis of α-amylase.
7. Stomata close by its effect so it control on transpiration.

Question 25.
What is apical dominance?
Or
One plant showing usual growth in length but its lateral branches are not developing. Why it so? What will you suggest for development of lateral branches in plant?
Answer:
Generally in plants in presence of apical bud the growth of lateral and axillary buds completely or partially suppressed.

This character is known as apical dominance. It is the main property of auxin plant hormone. Auxin secreted in plant apex. Due to the effect of this the growth of axillary/lateral buds present on stem inhibits and apical growth is continue in plants. If apical bud is removed then lateral and axillary bud start to develop.

Question 26.
How the amount of hormone secretion is regulated. Explain.
Or
Explain the process of hormone feedback mechanism.
Answer:
Hormones should be secreted in precise quantities, otherwise many harmful effects can occur. The timing and amount of hormone released are regulated by feedback mechanisms. For example, if the sugar levels in 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 27.
Write the functions of estrogen hormone found in female.
Answer:
Functions of estrogen hormone –
1. This hormone is called feminizing hormone.
2. This hormone is necessary for complete development of female repro-ductive organ.
3. Estrogen hormone develops the secondary sexual characters. As thin voice (high pitch of voice) of female, storage of fat, starting of menstrual cycle, development of breasts, development of hairs on external reproductive organs etc.

Question 28.
What are induced movements? Explain with example the chemotaxis movements.
Ans. Induced movements: They are induced by external stimuli and these move-ments are also called tactic movements. The stimuli which induce these movements can be light, chemical substances or heat. The direction of movement may depend on the source of stimuli.

Chemotaxis movements: Due to chemical stimulus response the moverhent takes place, is called chemotaxis movements. In fern and moss plants the anthero- zoids movement towards egg cell due to secretion of special chemical material malic acid by archegonia.

Question 29.
What is geotropism? Explain.
Answer:
Plants show the tropic movement after responding the different stimuli. Environmental triggers such as light, or gravity will change the directions that plant parts grow in. These directional, or tropic, movements can be either towards the stimulus, or away from it. So the roots of a plant always grow downwards while the shorts usually grow upwards and away from the earth.

This upward and downward growth of shoots and roots, respectively, in response to the pull of earth or gravity is geotropism (see diagram). So movement of any part of the plant towards the gravity of earth or in opposite side is called geotropism.

Plant showing geotropism

Question 30.
Name the hormone secreted by endocrime glands and also write their functions.
Answer:

S.No.	Endocrine	Hormone	Gland Function
1.	Pituitary gland	Growth hormone	Stimulates growth in all organs
2.	Hypothalamus	Releasing hormone	Stimulates the secretion of hormones by pituitary gland
3.	Thyroid gland	Thyroxine	Regulates metabolism for body growth
4.	Pancreas	Insulin	Regulates blood sugar level
5.	Testes	Testosterone	Develops sexual characters in male.
6.	Ovaries	Estrogen	Development of female sex organs, regulates menstrual cycle
7.	Adrenal gland	Adrenaline	Prepare body to fight against odd situations.

Question 31.
Write four differences in plant hormone and animal hormone.
Answer:
Differences between plant and animal hormones –

Plant Hormone	Animal Hormone
1. There is no special gland for secretion of plant hormone.	Animal hormones are secreted by endocrine glands.
2. They are less in number.	They are of different types.
3. They regulate growth development.	They regulate every type of function, in this growth and development is also included.
4. Example – Auxin Gibberelline.	Example – Growth hormone, Thyroxine hormone.

Question 32.
What is synapse? Explain.
Answer:
Axon of one neuron is situated near the dendrites of next neuron. The junction of two neuron is called synapse. In synapse in between axon of one neuron and dendrites of other neuron there is a slight gape. This gap is called synaptic cleft. In synapse, impulses are transmitted from one neuron to next neuron. When an impulse reaches to a nerve cell axon end then a chemical, release in synaptic cleft and this material produce the impulse, in next neuron.

Question 33.
What functions are performed by synapse? Explain.
Answer:
Synapse perform the following functions—

1. It send the message one neuron to next neuron.
2. It decide that nerve impulse move only in one direction.
3. It summing the effects of all impulses helps in information resources.
4. It does not allow to forward the low level stimulus and remove them.

Question 34.
Explain the benefits of reflex action?
Answer:
1. Reflex action takes place very quickly due to reflex arch being very small, which can save the creatures from the fatal effects of situations.
2. These actions that occur as a result of external and internal stimuli are controlled by spinal cord. This reduces the pressure of brain function. After the action has taken place the information is transmitted to the brain.

Essay Type Questions

Question 1.
Draw a labelled diagram of neuromuscular junctions and explain its functioning.
Answer:

(a) Structure of neuron, (b) Neuromuscular junction
A space is found at the end of the nerve cell and at the joining site of muscle cell which is called synapse. When the electrical sigai reaches the end of the nerve cell, it releases some chemicals. These chemicals cross the synapse and reach the muscle cell and initiate electrical impulses which induce contration in the muscle cell.

Question 2.
What is endocrine glands? With the help of diagram write the name of glands and their location found in human. Write the function of hormone secreted by any two glands.
Answer:
Endocrine glands: These glands pour their secretion directly into blood and do not have ducts, so they are also called ductless glands. The secretion of these glands called hormones.


Endocrine glands in human beings (a) male, (b) femaleIn human following endocrine glands are found and their location is as under (see diagram).

1. Pituitary gland
2. Thyroid gland
3. Parathyroid
4. Adrenal gland
5. Thymus gland
6. Pineal body
7. Pancreas
8. Reproductive glands (testes and ovary)

(1) Thyroid gland: It is located on either side of the trachea in the neck region below the larynx, the gland secrets thyroxine and triodothyronine. Iodine is present in high amount. Thyroxine hormone is having following functions –

1. It increases the speed of cellular respiration.
2. It is essential for general growth of body specially for development of bones, hair etc.
3. Usual functions of reprdocutive organs are based on the activity of these hormones.
4. These hormon combine to pituitary gland hormone control the water-balance of the body.

(2) Pancreas: It is the second largest gland of human body. Pancreas is a gland that is partly exocrine and partly endocrine. Insulin hormone secreted by it have the following functions –

1. Insulin keeps the general level of glucose in blood and induces the conversion of excess glucose into glycogen in liver and muscles.
2. This hormones increases the utilisation of glucose. In this way, it keeps the level of sugar low in our blood. This hormone induces anabolism and growth.

Question 3.
How animals prepare themselves to run or fight in a scary situation? Explain.
Answer:
When animals are in a scary situation, their bodies have to prepare for either fighting or running away. Bolh are very complicated activities that will use a great deal of energy in controlled ways. Many different tissue types will be used and their activities integrated together is these action. However, the two alternate activities, fighting or running, are quite different. So here is a situation in which some common preparations can be usefully made in the body. This is done in many animals, including human beings, using a hormone called adrenaline that is secreted from the adrenal glands.

Adrenaline is secreted directly into the blood 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 supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs. Hiis diverts the blood our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragn and the rib muscles. All these responses together enable the animal body to be ready to deal with the situation.

Question 4.
Draw labelled diagram of human brain. In how many parts is divided? Describe the function of each.
Answer:
Brain: Human brain is highly developed delicate organ protected by bony cranium. The brain is covered by three membranes, which is also surrounded by a fluidy substance. Brain is having three main parts –

1. Fore brain
2. Mid brain
3. Hind brain.

(i) Fore brain: It makes up about two- third of the human brain. It is die main part of brain, so it is called ‘large brain’.
It is highly developed part of the brain. This is the base of memory, consiousness, intelligence and proficiency. Our five sense organs (eye, nose, ear, skin and tongue) directly related to crebrum. Cerebrum analyse and coordinate the received urg.

Human brain

Functions of fore brain –

1. It receives the message from all sensory organs.
2. It create the balance between stimulus and activities.
3. It gives order to all muscles, glands and organs for right action.
4. It brings the changes in our behaviour on past experience and memory.
5. After receiving it store the all informations and knowledges.

(ii) Mid brain: It is the center of controlling the vision and hearing power.
(iii) Hind brain: It is also called cerebellum.
It keeps the equillibrium of the body that means it control the accurate movement. Our walking, running, standing, sitting etc. all are controlled by it. It also control on contraction of voluntary muscles and it receives the sensation from equillibrium part of internal ear.

Question 5.
What is reflex action and reflex arc? Explain its working giving examples
Answer:
In animals for the external changes i.e. stimuli two type of process takes place – voluntary and involuntary. Involuntary activities not under controlled of animal.
On touching the hot object or prick by needle or spine, we quickly move our hand or leg. A reflex action is a fast automatic response to a stimulus. The conduct of these activities by spinal cord.

In reflex action, sensory organs receive the stimulus and through sensory nerves send to spinal cord. From spinal cord for responses order get the related muscles through motor nerves and organ respond it. In this way sensation from sensory organs through sensory fibres come to spinal cord or inform of inspiration from spinal cord the message send to muscles of responding organs. This path is called reflex arc and process is called reflex action.

Reflex arc