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Class 10 Science Chapter 7 Control and Coordination
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Control and Coordination
Chapter – 7
GENERAL SCIENCE
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 a voluntary action, which requires our thinking and is within our control.
Q.2. What happens at the synapse between two neurons.
Ans: A synapse is a gap between the two neurons. At the synapse, the electrical signals are converted into chemicals that can easily cross over the gap and pass on to the next neurons where it is again converted into an electrical signal.
Q.3. Which part of the brain maintains posture and equilibrium of body?
Ans: Cerebellum. This is the back of the brain. It coordinates voluntary muscle movements and helps to maintain posture, balance, and equilibrium.
Q.4. How do we detect the smell of an agarbatti (incense sticks)?
Ans: Smell of an incense stick is detected by the olfactory receptors present in the nose. 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: In a reflex action, the brain plays no part. The spinal cord, which reacts without thinking about how to respond to stimuli, is in charge of these automatic actions. They receive information from all parts of the body and integrate it.
Page – 122
Q.1. What are plant hormones?
Ans: Plant hormones are chemical compounds present in very low concentration in plants. 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: The type of movement of leaves of the sensitive plant is known as a nastic movement. But the movement of shoot is directional towards light.
This type of movement does not depend on the direction of stimuli. 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: Auxin is a plant hormone that promotes growth.
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 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. 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: Chemical coordination takes place in animals with the help of chemical messengers called as 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 regulate the growth, development and homeostasis of the animals.
Q.2. Why is the use of iodised salt advisable?
Ans: Iodine is essential for the thyroid gland to produce 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. This deficiency disease is known as goiter. Therefore iodized salt is advised.
Q.3. How does our body respond when adrenaline is secreted into the blood?
Ans: When secreted in large amounts it speeds up the heartbeat and hence supplies more oxygen to the muscles. The breathing rate also increases due to contractions of diaphragm and rib muscles. It also increases the blood pressure. All these responses enable the body to deal with any stress or emergency.
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.
EXERCISES
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 present in all parts of the body for example in the skin, eyes, nose 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:
Function:
(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: Phototropism is the directional response of a plant that allows the plant to grow towards or in some cases away from the light. 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.
As both of these signals meet in a bundle in the spinal cord, so, if there is any spinal cord injury then both of these signals will be disrupted.
Q.8. How does chemical coordination occur in plants?
Ans: Chemical coordination occurs in plants with the help of phytohormones or plant hormones secreted by plants. Auxin, cytokinin, gibberellin, abscisic acid are plant hormones. These hormones regulate the growth and development of the plants. They also regulates various metabolic activities in the plants. 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: An organism needs control and coordination system for the following functions:
(i) To save the body of the organisms from the harmful changes in the environment.
(ii) To control the speed of voluntary and involuntary actions.
(iii) To have the capability to think and learn for responding to any stimuli.
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.
The difference between involuntary actions and reflex actions are:
| Involuntary actions | Reflex actions |
| Involuntary actions are the actions which are not controlled by our will. | Reflex actions are the sudden action in response to something. |
| They do not need any kind of stimulus to work. | They required stimulus for its action. |
| These actions are regulated by the brain. | These actions are regulated by the spinal cord. |
| They do not involve skeletal muscle. | They do involve skeletal muscle. |
| These actions are performed throughout one’s life. | These actions are produced in response to an event of an emergency. |
| This action may be quick or slow. | Reflex actions are always quick. |
| For example: The beating of the heart is an involuntary action. Salivating when food is put in the mouth. | For example: Immediate withdrawal of hands upon touching a hot cup of tea. Closing the eyes, when bright light is focused. |
Q.11. Compare and contrast the nervous and hormonal mechanism for control and coordination in animals.
Ans:
| Nervous system | Hormonal system |
| It consists of the central nervous system (CNS) and peripheral nervous system (PNS | It consists of endocrine glands |
| Nervous system has a network of nerves spread through out the body. | Hormonal system does not has such a network. |
| Neural responses are quick and short-lived | Hormonal effects are slow but are long term |
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 the sensitive plant is involuntary action, but the change in our legs is a voluntary action.
Plants have some specialized protein for the movement in sensitive plants. But animals have some concentrated protein. This protein helps the muscles to move.
There are two types of tissues helps to transfer the information in the animal cell, but there is no cell is available in a plant cell.
Our legs are provided with nerves which have connection with muscles. To lift the leg, the brain passes information to nerves.
Multiples Choice Questions:
Q.1. Spinal cord originates from:
(a) Cerebrum.
(b) Medulla.
(c) Pons.
(d) Cerebellum.
Ans: (b) Medulla.
Q.2. Select the mis – matched pair:
(a) Adrenaline: Pituitary gland.
(b) Testosterone: Testes.
(c) Oestrogen: ovary.
(d) Thyroxine: Thyroid gland.
Ans: (a) Adrenaline: pituitary gland.
Q.3. Which of the following is not an involuntary action?
(a) Vomiting.
(b) Salivation.
(c) Heart beat.
(d) Chequing.
Ans: (d) Cheung.
Q.4. Which of the following endocrine glands is unpaired?
(a) Adrenal.
(b) Testes.
(c) Pituitary.
(d) Ovary.
Ans: (c) Pituitary.
Q.5. The substance which accelerates the growth in stem is
(a) Vitamin.
(b) Enzyme.
(c) Auxin.
(d) Chlorophyll.
Ans: (c) Auxin.
Q 6. Auxins are
(a) Hormones.
(b) Proteins.
(c) Fats.
(d) Cell organelles.
Ans: (a) Hormones.
Q.7. Which one of the following endocrine glands produces two distinct hormones?
(a) Adrenal.
(b) Thymustert.
(c) Testis.
(d) Pineal.
Ans: (a) Adrenal.
Q.8. Brain and spinal cord act as
(a) Receptors.
(b) Effectors.
(c) Modulators.
(d) None of these.
Ans: (c) Modulators.
Q.9. Autonomous nervous system does not control.
(a) Thinking and learning.
(b) Heart beat.
(c) Excretion.
(d) Reflex.
Ans: (a) Thinking and learning.
Q.10. Movement in the leaf of the touch – me – not plant is:
(a) Epinasty.
(b) Hyponosty.
(c) Nyctinasty.
(d) Seismonasty.
Ans: (d) Seismonesty.
Q.11. Which one of the following is not endocrine glands?
(a) Pituitary.
(b) Thyroid.
(c) Adrenal.
(d) Salivary.
Ans: (d) Salivary.
Q.12. Hormone is
(a) Enzymatic product.
(b) V Chemical messenger.
(c) Nerve impulse.
(d) Excretory product.
Ans: (b) Chemical messenger.
Q.13. Glucose level of blood is regulated by
(a) Thyroxin and calcium.
(b) Insulin and glucagon.
(c) Insulin and thyroxin.
(d) Glucagon and thyroxine.
Ans: (b) Insulin and glucagon.
Q.14. Blood pressure is controlled by
(a) Adrenal gland.
(b) Thyroid.
(c) Thymus.
(d) Pancreas.
Ans: (a) Adrenal gland.
Q.15. Growth hormone is produced in
(a) Thyroid.
(b) Adrenal.
(c) Gonads.
(d) Pituitary.
Ans: (d) Pituitary.
Q.16. Male hormone is
(a) Entrogen.
(b) Testosterone.
(c) Adrenalin.
(d) FSH.
Ans: (b) Testosterone.
Q.17. Which plant hormone causes bending of shoot towards light?
(a) Auxin.
(b) Gibberellin.
(c) Cytokinin.
(d) Ethylene.
Ans: (a) Auxin.
Q.18. The growth of pollen tubes towards ovules is the example of
(a) Hydrotropism.
(b) Geotropism.
(c) Chemotropism.
(d) Phototropism
Ans: (c) Chemotropism.
Q.19. Which of the following is a plant hormone?
(a) Thyroxine.
(b) Insuline.
(c) Oestrogen.
(d) Cytokinin.
Ans: (d) Cytokinin.
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