These NCERT Solutions for Class 10 Science Chapter 7 Control and Coordination Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.
Control and Coordination NCERT Solutions for Class 10 Science Chapter 7
Class 10 Science Chapter 7 Control and Coordination InText Questions and Answers
In-text Questions (Page 119)
Question 1.
What is the difference between a reflex action and walking ?
Answer:
Reflex action: “A spontneous; automatic and mechanical response to a stimulus acting on a specific receptor without the will of an animal”. For e.g. blinking of eyes, coughing, yanwing, sneezng etc.
Walking : Hind brain : It has three regions : cerebellum, pons varolii, medulla oblongata.
(a) Cerebellum : maintains the posture and equilibrium.
(b) Pons varolii : Controls some aspects of respiration.
(c) Medulla oblongata: Controls rate of heart-beat, breathing movements, swallowing, coughing, sneezing vomitting etc.
Question 2.
What happens at the synapse between two neurons ?
Answer:
Both axon and dendrites arise from cell body. The functional junction between neurons is called synapse. The synapse is a gap between a pair of adjacent neurons. The functional unit of nervous system is neurons. Cyton contains a nucleus within the cytoplasm and Nissl granules formed of ribo nucleic acid (RNA) and thread like fibres called neurofibrils of cytons within brain and spinal cord called a nucleus.
Question 3.
Which part of the brain maintains posture and equilibrium of the body ?
Answer:
Cerebellum, maintains the posture and equilibrium of the body.
Question 4.
How do we detect the smell of an agarbatti (increase sticks) ?
Answer:
Olfactory Lobes : These receives impulses from olfactor receptors which are organs of smell in the nose with the help of the organs we can detect the smell of an agarbatti.
Question 5.
What is the role of the brain in reflex action ?
Answer:
At the time of reflex action, the action is stimulated by the spinal card, but information is also sent to the brain. The main work is done by the spinal card.
In-text Questions (Page 122)
Question 1.
What are the plant hormones ?
Answer:
The function of control and coordination in plants in performed by chemical substances known as plant hormones. For example, Auxins, Gibberellins, Cytokinin, Abscisic acid and Ethylene, These hormones are plant growth hormones whose function are :
- Auxins: It promotes cell enlargement and cell differentiation in plants. It also promotes fruit growth.
- Cytokinins : It promotes cell-division in plants. It helps in breaking dormancy of seeds and buds. Cytokinins activate the opening of stomata and also promote fruit growth.
- Gibberellins : It promotes cell enlargement and cell differentiation in the absence of auxins It helps in breaking dormancy in seeds and buds and also promotes fruit growth.
- Abscisic Acid : It supports dormancy in seeds and buds. It supports closing of stomata. It also helps in falling of leaves, floral parts of fruits etc.
- Ethylene; It supports in ripening of fruits and also helps in breaking and bud dormancy
Question 2.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Answer:
The movement of leaves of the sensitive plant is seismonastic movement occur in response to touch (shock) is best seen in ‘Touch-me-not’ plant (Mimosa pudica). It is called ‘Lajwanti’ or ‘Chhuimui’ plant. If we touch the leaves of the Mimosa plant with our finger we find that all its leaves fold up and droop after sometime, the leaves regain their original status. It is called tropic movement. The movement of a shoot towards light is called phototropic movement.
Question 3.
Give an example of a plant hormone that promotes growth.
Answer:
Growth promoters: These stimulate the plant growth e.g. auxins, gibberellins, cytokinins and ethylene.
Question 4.
How do auxins promote the growth of a tendril around a support?
Answer:
Auxins generally in habit flowering. Auxins regulate some of the important plant growth movements, e.g. phototropism and geotropism. These promote cell enlargement and cell differentiation in plants. Auxins induce apical dominance, e.g. the influence of apical bud in suppressing the growth of lateral buds. Like the pea plant climb up other plants/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
Question 5.
Design an experiment to demonstrate hydrotropism.
Answer:
‘Hydro’ means water. Thus, hydrotropism is response of plants towards water.
To design the experiment–Self doing
In-text Questions (Page 125)
Question 1.
How does chemical coordination take place in animals?
Answer:
The integration of nervous system and hormonal system is brought about by hypothalamus. The hypothalamus is part of the brain. It secretes neurohormones which regulate the secretion of pituitary hormones. The pituitary hormones in term regulate the growth and secretions of their endocrine glands. In this way, both the system control and coordination various activities of the body.
Question 2.
Why is the use of iodized salt advisable ?
Answer:
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. Incase of iodine is deficient in our diet, there is a possibility that might suffer from goitre. The symptom of this disease is a swollen neck.
Question 3.
How does our body respond when adrenaline is secreted into the blood ?
Answer:
Adrenaline is also termed as emergency hormone. In normal situations, these hormones are secreted in small amount.
However, when a person faces stress or danger these are secreted in large amounts to prepare the body to face emergency situation These increase the rate of heartbeat and breathing blood pressure basal metabolic rate, and sugar level in blood. Because of the above roles of these hormones in fight/flight reaction. The adrenal above role are known as the gland of emergency.
Question 4.
Why are some patients of diabetes treated by given injections of insulin ?
Answer:
To control the digestion sugar (glucose) into glycogen and lowering the level of blood glucose in human beings. That’s why some patients of diabetes are treated by giving injection of insulin.
Class 10 Science Chapter 7 Control and Coordination Textbook Questions and Answers
Page No. 125
Question 1.
Which of the following is a plant hormone ?
Answer:
(d) Cytokinin
Question 2.
The gap between two neurons is called a:
Answer:
(b) Synapse
Question 3.
The brain is responsible for
Answer:
(d) All of the above.
Question 4.
What is the function of receptors in our body ? Think of situations where receptors do not work properly. What problems are likely to arise ?
Answer:
A receptor is a nerve cell/group of nerve cells which 15 sensitive to a specific stimulus/to a specific change in the environment. The animals have different sensory receptors/sense organs for receiving different stimuli such as thermo receptors heat and cold photoreceptors for light. phono recepto sound olfactory receptors for smell, gustato receptors for taste and tang receptors for touch. The receptors transmits nerve impulses to central nervous system. The latter transmits motor impulses to appropriate effectors (muscles/ glands) which produce suitable responses. If receptors do not work properly the animals could not receive the different stimuli such as thermo, heat, cold, light, sound, smell, taste and touch from the environment. The above said problems will rise up.
Question 5.
Draw the structure of a neuron and explain its function.
Answer:
Structure of Neuron: It is the structural and functional unit of nervous system.
A neuron consists of three parts
(i) Cell body (ii) Dendrites (iii) Axon
(i) Cell body: The cell body of a neuron is also called cyton/ soma. It has cytoplasm called neuroplasm, it has mitochondria, Golgiapparatus, neurofibrils, neurotubules, special granules called nissl’s gramules. It concerns with metabolic maintenance and growth.
(ii) Dendrites (Singular dendron): These are several short, tapering much branched protoplasmic processes stretching out from the cell body of a neuron. The conduct nerve impulses towards the cell body.
(iii) Axon: It is a single, very long, cylindrical protoplasmic process (nerve fibre) of uniform diameter arising from the cell body The cell membrane of the axon is called axotemma and its cytoplasm is termed axoplasm. Neurons transmit messages in the form of nerve impulses.
Special properties of Neurons.
- They do not divide.
- From shortly after birth, new neurons do not develop
- They are not repaired when injured.
- They are only glucose as a respiratory substrate.
- They die of deprived of oxygen for over five minutes.
Question 6.
How does phototropism occur in plants ?
Answer:
Plants are autotrophs i.e., they manufacture their own food in the presence of sunlight. Therefore, they respond to light by growing towards it. Plants also turn their leaves towards the sun to ensure that the latter get maximum sunlight.
Requirement: Two potted plants.
Method: Take two potted plants. Keep one plant in the open so that it receives the sunlight coming from above: place the other plant in a room near the window in such a way that it receives sunlight from one side only i.e. through window. After some days observe both the plants.
Observation: The first plant (which was kept in the open) has grown up straight towards light. The second plant which was kept in the room and receiving light from one side has grown by bending towards the light.
Explanation and conclusion: This movement of the plant part stem) is caused by the action of auxin hormone. The auxin hormone is formed by the meristematic tissue at the tip of stem.
(i) Auxin spreads uniformly Down the stem in plant kept in the open and receiving sunlight from above. Due to presence of auxin equally on the both sides the stem grows up straight because both the sides of the stem show growth at the same space.
(ii) The second plant is receiving light only from one side through the window. In this case the auxin hormone moves from tip of stem to be concentrated more on the side not receiving light.
Due to presence of more auxin hormone the shady side of stem grows faster than the side of stem receiving light. As a result, the stem bends towards the direction of light. This experiment shows that the stem of the plant responds to light by showing growth movement towards light (positive phototropism).
Question 7.
Which signals will get disrupted in case of a spinal cord injury ?
Answer:
It loses sensation when the nerve supplying it remains stopped/sudden response to a stimulus is called reflex action.
Question 8.
How does chemical coordination occur in plants ?
Answer:
In plants, control and co-ordination take place with the help of plant hormones (phytohormones). These are naturally occurring chemical substances secreted by specific parts of plants such as shoot apex, root apex and leaves. They control various activities and responses of plants such as elongation of stem, flowering, phototropism, geotropism etc.
Question 9.
What is need for a system of control and co-ordination in an organism ?
Answer:
The integration of nervous system and hormonal system is brought about by neuro hormones which regulates the secretion of pituitary hormones. The pituitary hormones in turn, regulate growth and secretions of other endocrine glands. In this way both the systems control and co-ordination various activities of body.
Question 10.
How are involuntary actions and reflex actions different from each other ?
Answer:
An involuntary action, on the other hand is performed by the animal without its will. It is very quick and the animal has no choice in it. Therefore, the same stimulus always gets the same response, for e.g. the hand foot is withdrawn every time it is suddenly pinched or pricked with a needle or touched by a hot object.
Reflex action: “A reflex action is a spontaneous, automatic and mechanical response to a stimulus acting on a specific receptor without the will of an animal is called reflex action.”
For e.g. blinking of eyes, coughing, yawing, sneezing movement of diaphragm during respiration etc.
Question 11.
Compare and contrast nervous and hormonal mechanisms for control and co-ordination in animals.
Answer:
| Nervous System | Hormonal Information |
| 1. It is sent as an electrical impulse along axons and a chemical across synapse. | 1. It is sent as chemical messanger via bloodstream. |
| 2. Information is directed to specific receptors one/a few nerve fibres, gland cells/other neurons i.e., it is addressed by name. | 2. Information is spread throughout the body by blood from which the target cell/organs pick it up. It is addressed to whom it may concern. |
| 3. Information travels rapidly in milli seconds. | 3. Information travels slowly. |
| 4. It gets response immediately. | 4. It gets response usually slowly. |
| 5. Its effects are short lived. | 5. Its effect are generally more prolonged. |
Question 12.
What is the difference between the manner in which movement takes place in a sensitive plant and movement in our legs?
Answer:
Seismonastic movements : Such movement occur in response to touch (shock). Seismonastic movement are best see in ‘touch me not’ plant (Mimosa-pundica). It is also called ‘lajwanti’ or Chhuimui plant. It we touch the leaves of mimosa plant with our finger, we find that all its leaves fold up and droop. After sometimes the leaves will remian their original status.
Mechanism of Reflex action: A reflex action works in this way.
- Receptor organ : It receives the stimulus and initiates a sensory nerve impulse.
- Sensory nerve fibre: It conducts impulses from receptor to the spinal cord.
- Spinal cord : It acts as modulator and changes sensor impulse into the motor impulse.
- Motor Nerve fibre : It conducts motor nerve impulse from spinal cord to effectors.
- Effector organ : It gives the response. This produces either the movement of some muscles/ secretion from a gland.
Relflexs travels in the following sequence:
Stimulus → Receptor organs → Sensory nerve → Spinal cord → Motor nerve → effector organ → Response to stimulus
Class 10 Science Chapter 7 Control and Coordination Textbook Activities
Activity 7.1 (Page 115)
Question 1.
Put some sugar in your mouth. How does it taste ?
Answer:
When we put some sugar in our mouth, our tongue starts watering and it taste sweet.
Question 2.
Block your nose by pressing it between your thumb and index finger. Now eat sugar again. Is there any difference is its taste ?
Answer:
The receptors are usually located in out sense organs such as the inner ear, the nose, the tongue and so on. So gustatory receptors will detect taste while olfactor receptors will detect smell and deficiency of oxygen.
Question 3.
While eating lunch, block your nose in the same way and notice if you carefully appreciate the taste of your food which you are eating.
Answer:
No, we do not appreciate the taste of food.
Activity 7.2 (Page 121)
- Fill a conical flask with water.
- Cover the neck of flask with a wire mesh.
- Keep two or three freshly germinated bean seeds on the wire mesh.
- Take a cardboard box which is open from one side.
- Keep the flask in the box in such a manner that the open side of the box faces light coming from a window. (Fig.)
- After two or three days, you will notice that the shoots bend towards light and roots away from light.
- Now turn the flask so that the sheets are away from light and the roots towards light. Leave it undisturbed in this condition for a few days.
Question 1.
Have the old parts or the shoot and root changed direction ?
Answer:
Yes, the old part of the shoot have moved towards the light. The roots parts have moved way from the light.
Question 2.
Are there differences in the direction of the new growth ?
Answer:
The new growth is opposite.
Question 3.
What can we conclude from this activity ?
Answer:
The shoot system show positive response to light and root system shows negative response to light.
Activity 7.3 (Page 123)
- Look at Fig.
- Identify the endocrine glands mentioned in the figure.
- Some of these glands have been discussed in the text. Consult books in the library and discuss with your teachers to find out about the functions of other glands.
Endocrine glands in human beings in male and female
Gland: A cell, a tissue, or an organ which secretes certain useful chemical compounds required for particular functions is called a gland. There are three types of gland.
(i) Exocrine glands: These glands have duets for discharging their secretions on the body surface or into the body.
(ii) Endocrine glands: These glands lack duets and pass their secretion into the surroundings blood for transport to the site of action. They are also called ductless gland/glands of internal secretion. Their secretions are known as hormones/internal section for e-g. Pituitary, thyroid, parathyroid glands, adrenal secret glands etc.
(iii) Heterocrine glands: These glands consists of both exocrine and exocrine tissue.The exocrine tissue sends its secretion/ products by way of a diet. The endocrine tissue discharges its secretion into the blood. For eg pancreas and gonads (Testes and ovaries) Human body possesses large number of endocrine glands called which elaborate store and release chemical messengers hormones. These endocrine glands are;
(i) Hypothalamus: Pituitary (hypophysis). Thyroid gland, parathyroid gland, pancreas, adrenal glands, pineal glands. Thymus gland, Testes (males) and ovaries in (females).
1. Hypothalamus: It is situated at the base of the brain and is composed of nervous tissue. The
neurosecretary cells of the hypothalamus secrete several neurohormones called Releasing hormones (RH) and inhibiting factors/hormones.
2. Pituitary gland (Hypophysis): Pituitary gland is present just below the brain. It is a small, red-grey, pea-shaped attached to the hypothalamus of the brain by a stalk-or in fundibulum.
Pituitary gland consists of three lobes :
(a) Anterior lobe (b) Intermediate lobe (c) Posterior lobe.
All three lobes of the pituitary secretes separate hormones.
A. Anterior lobe of pituitary: It produce six hormones.
(i) Follicle-Stimulating Hormone [FSHI]: It stimualtes sperm formation in male and growth of ovarian follicles in female.
(ii) Luteinising Hormone [LH]: In male, it induces the testes to produce male sex hormones named androgens (Testosterone).
(iii) Thyroid-Stimulating Hormone [TSH]: It stimulates growth of thyroid gland and production of thyroid hormones.
(iv) Adreno cortico Trophic Hormones [ACTH]: It stimulates the adrenal cortex to grow and secrete its hormones.
(v) Somatotrophic/Growth Hormones (STH/ GHI): It stimulates growth and development of all tissues by accelerating protein Synthesis and cell division, and by retaining calcium in the body.
(vi) Protactin Hormone [PH] or Luteotrophic Hormones: It Stimulates the growth of milk glands during pregnancy and the secretion of milk after delivery of the child.
B. Intermediate lobe of Pituitary: It secretes a single hormone named melanocyte stimulating hormone (MSH). The hormone stimulates the synthesis of black pigment melanin in the skin, and also causes dispersal of melamin granules in the pigment cells.
C. Posterior lobe of Pituitary :It stores and releases two hormones.
(i) Oxytocin [OT]; It induces contractions of smooth muscles of the uterus during the birth of the young one and myoepithelia cells of the mammary glands to cause release of milk during sucking by the infant.
(ii) Vasopressin: It is also called antidiuretic hormone [ADH] it decreases the loss of water in the urine by increasing the reabsorption of water in the distal convoluted tubules.
3. Thyroid gland: It is the largest endocrine gland. It is a bilobed structure situated in the neck region. Hie thyroid gland secretes three hormones.
(i) Thyroxine (T4)1 (ii) Triodothyromine (T3)2 (iii) Calcitonin
4. Parathyroid glands: There are four small flat; oval glands situated on the posterior surface of the thyroid gland, two in each lobe of the thyroid. They secrete parathormone [PTH]. It is also called collip’s hormones and regulate the calcium-phosphorus balance in the. blood.
5. Adrenal glands: These are a pair of glands situated on upper side of each kidney. Therefore they are also called syprarenals.
(a) Adrenal cortex : It is firm, outer pale yellowish pink region essential for life. It secretes three hormones mineral corticoids-The help in control the sodium and Potassium.
(i) Gluco corticoids : They regulate the metabolism of carbohydrate proteins and fats.
(ii) Sex corticoids : They stimulate the development of secondary sexual characters both in males and females.
(b) Adrenal medulla : It is an internal, soft, dark reddish tissue of adrenal gland. It enables the animal to face physical emotional stress.
6. Pancreas: Pancreas lies below the stomach. It is an elongated and emotional stress yellowish gland. It consists largely of lobules that secrete pancreatic ice. The lobules are cells, called Islets of Langerhans’ which reproduce hormones, Islets of Langerhans secretes two hormons.
(a) Insulin by B cells
(b) Glucagon b o cells
7. Testes : In males, a pair of testes are extra abdominal in position and located in scrotum. Testes secrete male sex hormones.
8. Ovaries : A pair of ovaries lies in the abdomen in females. They secrete three female sex hormone
(i) Estrogen (ii) Progesterone (in) Relaxin.
9. Pineal: It is a very small, reddish-grey; vascular, solid body lying between the two cerebral hemispheres of the brain. It secretes melatonin hormone.
10. Thymus gland: It is situated in the upper chest near the front side of the heart. It secretes thymosin hormone which stimulates the development and differentiation of lymphocytes and thereby increasing resistance to infection.
Class 10 Science Chapter 7 Control and Coordination Additional Important Questions and Answers
Very Short Answer Type Questions
Question 1.
Name the structural and functional unit of nervous system.
Answer:
Neuron.
Question 2.
Write full form of (a) PNS (b) CNS.
Answer:
(a) PNS-Peripheral nervous system
(b) CNS-Central nervous system.
Question 3.
Mention the two parts of CNS.
Answer:
CNS is divided into two parts
Question 4.
What is the weight of fully grown brain ?
Answer:
1200-1400 gm.
Question 5.
Name the box in which brain is situated ?
Answer:
Cranium
Short Answer Type Questions
Question 1.
What is Cranium ? What is its function ?
Answer:
Cranium is a bony covering that encloses the brain. Its function is to protect the brain from mechanical injury.
Question 2.
What are Meanings ? What is their function ?
Answer:
Meanings are the three membrances that surround the brain. The space between these membrance is filled with cerebral spinal fluid. These membranes and the cerebro spinal fluid protect the brain from mechanical shocks.
Question 3.
Name the main parts of nervous system of grasshopper.
Answer:
The nervous system in grasshopper consists of a bilobe cerebral ganglion (brain) in the head region, long verbral nerve cord extending from brain to almost end of the body, several ganglia at specific regions and nerves extending from ganglia and spreading to various parts of the body.
Long Answer Type Question
Question 1.
How do we detect that we are touching a hot object ?
Answer:
All information from our environment is detected by the specialised tips of some nerve cells. These receptors are annually located in our sence organs, such as the inner ear, the nose, the tongue etc. The nerves from all over the body meet in a bundle in the spinal cord on their way to the brain. For example, when we touch a hot object, the receptor send a signal to the spinal card, the spinal card responses quickly and send signals to remove the hand from the hot object.
Multiple Choice Question
Question 1.
The nervous tissue is made up of an organised networks
(a) Cells
(b) Nervous
(c) Muscles
(d) None of the above
Answer:
(b) Nervous
Question 2.
Reflex action is mainly controlled by the-
(a) Spinal cord
(b) brain
(c) muscles
(d) skull
Answer:
(a) Spinal cord
Question 3.
Writing talking etc, are
(a) voiunatary activities
(b) involuntary actions
(c) (c) can be (a) or (b)
(d) none of the above
Answer:
(a) voiunatary activities
Question 4.
The main thinking part of the brain is-
(a) hind-brain
(b) mid-brain
(c) fore brain
(d) skull
Answer:
(c) fore brain
Question 5.
The brain is protected by the
(a) skull
(b) mouth
(c) head
(d) teeth
Answer:
(a) skull