Class 10 Science Chapter 7 Control and Coordination The answer to each chapter is provided in the list so that you can easily browse throughout different chapters NCERT Class 10 Science Chapter 7 Control and Coordination and select need one.
Class 10 Science Chapter 7 Control and Coordination
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Control and Coordination
Chapter – 7
TEXTUAL QUESTIONS AND ANSWERS
Page – 119
Q.1. What is the difference between a reflex action and walking ?
Ans :- Reflex action is a spontaneous involuntary or automatic nerve mediated response to a stimulus produced at the unconscious level . But walking is the movements of muscles of legs controlled by brain.
Q.2. What happens at the synapse between two neurons.
Ans :- At synapse , information carrying neuron’s axon end , electrical impulse sets off the release of some chemicals . These chemical cross the gap or synapse and reach to dendrites of the next neuron and start electrical impulse there.
Q.3. Which part of the brain maintains posture and equilibrium of body ?
Ans :- Cerebellum.
Q.4. How do we detect the smell of an agarbatti ( incense sticks ) ?
Ans :- Smell of an agarbatti is sensed by receptor in the nose and the information is transmitted to olfactory lobe located in the fore brain which interprets the information.
Q.5. What is the role of brain in reflex action ?
Ans :- Brain is the main co – ordinating centre of the body . The brain and spinal cord constitute the central nervous system . They receive information from all parts of the body and integrate it .
Q.1. What are plant hormones ?
Ans :- These are chemical compounds secreted by plants which diffuse all around the other cells and regulate the activities . Plant hormones help to co – ordinate growth , development and responses to the environment .
Q.2. How is the movement of leaves of sensitive plant is different from movement of a short towards light ?
Ans :- Movement of leaves of the sensitive plant is not directional to the stimulus of touch . But the movement of shoot is directional towards light .
Movement of leaves of sensitive plant is due to change in the amount of water present in them . The movement of the shool towards light is due to growth controlled by growth hormone .
Q.3. Given an example of plant hormone that promotes growth .
Ans :- Auxin .
Q.4. How do auxins promote growth of a tendril around a support .
Ans :- Some plants like the pea plant climb up other plants or support 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 port of the tendril away from the object . This causes the tendril to circle around the object and thus cling to it . It is due to accumulation of auxins .
Q.5.Design an experiment to demonstrate hydrotropism.
Ans :- Growth movements in response to the stimulus of moisture are termed as hydrotropic movements .
Place some ready to germinate seeds of pea in moist sawdust in a shallow box whose bottom has been replace by a wire gauze .
Keep the apparatus undisturbed for 2-3 days . keep the sawdust moist . After some time radicals will pass through the sieves . Then the radicles curve upwards again to enter into the moist sawdust . the roots are positively hydrotropic and the curvature is more than that due to entropic effect .
Page – 125
Q.1. How does chemical coordination take place in animals ?
Ans :- It is brought about by chemical messengers called hormones . They are secreted by endocrine glands . The hormones are carried by the blood to the site of action . The hormones are consumed during their action . Hormones provide wide ranging changes .
Q.2. Why is the use of iodised salt advisable ?
Ans :- Iodine is necessary for the thyroid gland to make thyroxin hormone . 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 case iodine is deficient in our diet , there is a possibility that we might suffer from goitre . So to avoid deficiency of iodine , iodised salt is recommended .
Q.3. How does our body respond when adrenaline is secreted into the blood ?
Ans :- Adrenaline is secreted from adrenal gland . 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 beat 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 . This diverts the blood to our skeletal muscles . The breathing rate also increases because of the contractions of the diaphragm and the rib muscles.
Q.4. What are some patients of diabetes treated by giving injections of insulin ?
Ans :- Insulin is a hormone which is produced by the pancreas and helps in regulating blood sugar levels . If it is not secreted in proper amounts the sugar level in the blood rises causing many harmful effects .
Q.1. Which of the following is a plant hormone ?
( a ) Insulin.
( b ) Thyroxin.
( c ) Oestrogen.
( d ) Cytokinin.
Ans :- ( d ) Cytokinin.
Q.2. The gap between two neurons is called a
( a ) Dendrite.
( b ) Synapse.
( c ) Axon.
( d ) Impuls.
Ans . ( b ) Synapse.
Q.3. The brain is responsible for
( a ) Thinking.
( b ) Regulating the heart beat.
( c ) Balancing the body.
( d ) All of the above.
Ans :- ( d ) All of the above .
Q.4. What is the function of receptors in our body ? Think of a situation where receptors do not work properly . What problems are likely to arise ?
Ans :- Receptors are the specialised tips of some nerves. They are usually located in our sense organs like the nose the inner ear , the tongue etc.
The function of receptors is to detect information from the environment .
If receptors do not detect the information there will not be any co – ordination . It may lead to accidents . Body response will not be there .
Q.5. Draw a structure of a neuron and explain its function :
Ans :- Structure of neuron :
( i ) Dendrites of a neuron collect information from the receptor.
( ii ) Axon conducts information as electrical impulse .
( iii ) Terminal arborization pass the information as chemical stimulus at synapse for on ward transmission .
Q.6. How does phototropism occur in plants ?
Ans :- 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 , in two different kinds of phototropic movement , shoots respond by bending towards light while roots respond by bending away from it .
Q.7. Which signals will get disrupted in case of a spinal cord injury ?
Ans :- Reflex action will be disturbed because reflex arcs are located in the spinal cord . So , the quick responses needed to safe guard the body will not take place . The delayed responses may cause harm to the body.
Impulses from various body parts will not be communicated to brain . Messages from brain to body parts will not be communicated .
Q.8. How does chemical coordination occur in plants ?
Ans :- Plants lack well organised control mechanism as in animals . However plants respond to light , touch and gravitational force .
Moreover growth and movements in plants are regulated by external and internal factors .
Plant growth regulators or phytohormones are the chemical occuring in minute quantities and responsible for regulating metabolism , growth and development .
The important phyto hormones are auxin , gibberellins , cytokinins , ethylene and abscisic acid . All growth processes are regulated by one or more phytohormones acting synergistically or antagonistically .
Q.9. What is the need for a system of control and co che ordination in an organism ?
Ans :- Control and co – ordination system makes the various body organs and organs systems to work in organised pattern and in a coordinated way .
Control and co – ordination also aids in maintaining a steady stage between the internal environment of an organism and the external environment .
Q.10. How are involuntary actions and reflex actions different from each other ?
Ans :- Reflex actions are the spontaneous responses by voluntary organs but involuntary actions are by the involuntary organs .
Q.11. Compare and contrast the nervous and hormonal mechanism for control and coordination in animals .
|Nervous system||Hormonal system|
|( i ) The nervous system controls the various functions by the units called neurons.||( i ) Hormones are chemical messengers secreted by endocrine glands.|
|( ii ) Nervous system has a network of nerves spread through out the body.||( ii ) Hormonal system does not has such a network.|
|( iii ) The nervous system gets information from our sense organs and act throughout muscles to meet out.||( iii ) Hormones help in growth and development of the body controlling body metabolism , development secondary characters etc.|
Q.12. What is the difference between the manner in which movement takes place in a sensitive plant and the First movement in our legs ?
Ans :- The movement in sensitive plant leaves takes place in response to touch stimulus . When terminal pinnule is touched , the stimulus is conducted to its base and the pinnules droop sown . This happens in change in osmotic pressure causing shrinkage . When the stimulus time is over , osmotic pressure increases and the cells swell , the ipenneels become normal .
Our legs are provided with nerves which have connection with muscles . To lift the leg , the brain passes information to nerves .
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