Bihar Board Class 10 Science Solutions Chapter 7 Control and Coordination

 

Bihar Board Class 10 Science Chapter 7 Control and Coordination InText Questions and Answers

Intext Questions (Page 119)

Question 1.
What is the difference between a reflex action and walking ?
Answer:
Reflex action is a process by which we do something without thinking about it or without being in control of our – reactions. It is done by only the spinal cord without the help of brain. While walking is a process which is done by thinking, or it ‘i is performed by the brain unlike reflex action.

Question 2.
What happens at the synapse between two neurons?
Answer:
The electrical impulses set off the release of some . chemicals at the synapse between two neurons. These chemicals cross the synapse and start a similar electrical impulse in a dendrite of the next neuron.

Question 3.
Which part of the brain maintains posture and equilibrium of the body ?
Answer:
Posture and equilibrium of the body is maintained by v midbrain.

Question 4.
How do we detect the smell of an agarbatti (incense stick) ?
Answer:
The smell of an agarbatti is detected by the forebrain, There are separate areas of association where sensory impulses or information are interpreted by putting them together. These impulses of smell are. detected by forebrain.

Question 5.
What is the role of the brain in reflex action ?
Answer:
The nerves from all over the body meet in a bundle in the spinal cord. Reflex arcs are formed in the spinal cord itself although the information input also goes on to reach the brain.

Intext Questions (Page 122)

Question 1.
What are plant hormones?
Answer:
The chemical substances released by various parts of plants to control growth and various activities are called plant hormones.

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 neither towards nor away from stimulus like touch. While movement of shoot is towards stimulus like light. The movement of leaves of sensitive plants is not directional while the movement of shoot is directional.

Question 3.
Give an example of a plant hormone that promotes growth.
Answer:

• Auxins help to increase the length of plants.
• Gibberellins help in the growth of stem.

Question 4.
How do auxins promote the growth of a tendril around a support?
Answer:
The tendrils are sensitive to touch. As these tendrils come in the contact with the support, the auxin diffuses towards the other side away from the support. So this part gro^s more rapidly than the other. This causes the tendril to circle around the support and thus climb upwards.

Question 5.
Design an experiment to demonstrate hydrotropism.
Answer:
Positive hydrotropism can be demonstrated with germinated seedlings, which are allowed to grow on ground (Fig. 7.7). The soil below the roots is separated by a polythene partition. The left side is kept moist but the right side is kept dry. The radicals at first grow in a downward direction due to the effect of gravity (positive geotropism), but after some time, the roots bend toward the moist soil (positive hydrotropism). This is evidently due to the closeness of the germinating roots to water.

Intext Questions (Page 125)

Question 1.
How does chemical coordination take place in animals ?
Answer:
Chemical coordination takes place in animals with the help of some chemical substances called hormones. Hormones are secreted by endocrine glands. The timing and amount of hormone released are regulated by feedback mechanisms.

Question 2.
Why is the use of iodised salt advisable ?
Answer:
The use of iodised salt is advisable because iodine is necessary for the thyroid gland to produce thyroxine hormone. Thyroxine regulates carbohydrates, protein and fat metabolism in the body so as to provide the best balance for growth. Iodine is essential for the synthesis of thyroxine.

Question 3.
How does our body respond when adrenalin is secreted into the blood ?
Answer:
Adrenalin is secreted directly into the blood and is carried to different parts of the body. It acts on heart. As a result, the heart beats faster in order to supply more oxygen to our muscles. These muscles regulate various movements of the’body.

Question 4.
Why are some patients of diabetes treated by injectioAs of insulin ?
Answer:
The patients of diabetes are treated by giving injections of insulin. 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.

Bihar Board Class 10 Science Chapter 7 Control and Coordination Textbook Questions and Answers

Question 1.
Which of the following is a plant hormone ?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin
Answer:
(d) Cytokinin

Question 2.
The gap between two neurons is called a:
(a) dendrite
(6) synapse
(c) axon
(d) impulse
Answer:
(b) synapse

Question 3.
The brain is responsible for :
(а) thinking
(b) regulating the heartbeat
(c) balancing the body
(d) all of the above
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:
The main function of receptors is to detect informations from the environment. These receptors are located in our sense organs. There are some situations where receptors do not work properly, like mouth starts watering when we feel hungry, touching a flame, knee-jerk, etc. In these situations, they take enough time if these are done by the brain. To solve these problems, the nerves move muscles in a simpler way. This is done by the spinal cord.

Question 5.
Draw the structure of a neuron and explain its function.
Answer:

Function of neuron: The neuron is the structural and functional unit of the nervous system. It contains the following three parts :
(i) Dendrites
(ii) Cell body
(iii) Axon.
The impulses of information travel from dendrites to cell body, and then along the axon to its end. These impulses cross the synapse. At the end, the impulses travel from one neuron to the other up to the spinal cord or to the concerned part of body.

Question 6.
How does pdiototropism occur in plants ?
Answer:
The directional or tropic movement towards the light or away from the light is called phototropism. The shoots respond by bending towards light, while roots respond by bending away from the light.

Question 7.
Which signals will get disrupted in case of a spinal cord injury ?
Answer:
(i) All the signals and responses which pass from and to the brain through the spinal cord will get disturbed.
(ii) Reflex actions will be disrupted.

Question 8.
How does chemical coordination occur in plants ?
Answer:
In plants, stimulated cells release chemical compounds, which are called plant hormones. Different plant hormones help to coordinate growth development and responses to the environment. They are synthesised at places away from where they act and simply diffuse to the area of action.

Question 9.
What is the need for a system of control and coordination in an organism?
Answer:
Every little change in the environment evokes an appropriate movement in response. For example, if we want to talk to our friends in class, we whisper rather than shouting loudly. Thus, the movement to be made depends on the event that is triggering it. Therefore, such controlled movement must be connected to the recognition of various events in the environment, followed by only the correct movement in response. In other words, living organisms must use systems providing ‘ control and coordination. In multicellular organisms, specialised tissues are used to provide control and coordination activities.

Question 10.
How are involuntary actions and reflex actions different from each other ?
Answer:
Involuntary Action :
(i) The action which we cannot do by thinking is called involuntary action. For example, beating of the heart.
(ii) Involuntary actions are controlled by the brain.

Reflex Action :
(i) An action, i.e., a response which is mmediate (spontaneous) and does not need processing by the brain is called a reflex action. For example, immediate removal of hand on touching a hot plate.
(ii) Reflex actions are controlled by the spinal cord.

Question 11.
Compare and contrast nervous system and hormonal mechanisms for control and coordination in animals.
Or
Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify the statement.
Answer:
In human beings, the nervous system controls the various functions by small units called neurons. Neurons receive the information through sensory nerves and transfer them i through motor nerves. Besides this, certain important functions like sugar level, metabolism, growth and development, etc. are controlled by hormones secreted by various endocrine glands. Hence, it is true that nervous and hormonal systems together perform the function of control and coordination in human beings.

Question 12.
What is the difference between the mataner in which movement iri the sensitive plant and movement in our legs takes place ?
Answer:
Movement in sensitive plant: Movement in the sensitive plant leaves takes place in response to touch (shock) stimulus. When terminal pinnule is touched, the stimulus is conducted to its base and the pinnules droop down. This happens due to change (decrease) in osmotic pressure causing shrinkage. When the stimulus,time is over, osmotic pressure increases and the cells swell, causing to the pinnules become normal. This is an example of growth independent movement.

The sensitive plant Thus, movement happens at a point different from the point of touch (stimulus). So, the information that a touch has occurred is communicated through electricahchemical means from cell to cell, but not through specialised tissues. Plant cells change in shape by changing the amount of water , in them, resulting in swelling or shrinking, during movement.

Movement in our legs : Our legs are provided with nerves which are connected to muscles. To lift the leg, the brain passes information to nerves. The information travels as an electrical impulse. Oil reaching the leg muscles, the impulse is converted into a chemical signal and the muscles contract to lift the leg. Movement of legs takes place due to muscle contraction and relaxation, which is under the control of our nervous system.

In the nervous system, electrical impulses are generated for’ quick transmission of information. But there are limitations :
(i) Impulses will reach only those cells that are connected by the nervous tissue.
(ii) Once an electrical impulse is generated in a cell and transmitted, the cell takes some time to generate another impulse. That is, cells cannot continuously create and transmit electrical impulses.

Hormones are chemical messengers that diffuse to all cells of the body. The body cells, using special molecules on their surfaces, recognise information and even transmit it. Hormones are synthesised at places away from where they act. Hormones can reach all cells of the body (through blood in animals) regardless of nervous connections, and it can be done steadily and persistently.

Bihar Board 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:
Tt tastes sweet and the taste is identified by tongue and nose.

Question 2.
Block your nose. Now eat sugar again. Is there > any difference in its taste ?
Answer:
Yes, there is a difference in the taste of sugar.

Question 3.
While eating lunch, block your nose. Feel the taste.
Answer:
Students feel themselves.

Activity 7.2 (Page 121)

• Fill a conical flask with water.
• Cover the neck of the 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 windpw (Fig. 7.6 of your book).
• After two or three days, you will notice that the shoot bends towards light and roots away from light.
• Now turn the flask so that the shoots are away from light and the roots towards light. Leave it undisturbed in this condition for a few days.
  
  Fig. 7.6. Response of the plant to the direction of light

Question 1.
Have the old parts of the shoot and root changed direction ?
Answer:
The old parts of roots and shoots of plant change their directions slightly (very less), while new parts move more.

Question 2.
Are there differences in the direction of the new growth ?
Answer:
Yes, new parts change their directions more.

Question 3.
What can we conclude from this activity ?
Answer:
This activity shows that shoots show phototropism while the roots show geotropism.

Activity 7.3 (Page 123)

• Look at the Fig. 7.9.
  
• dentify the endocrine glands mentinncl in th fi’ure.

Question 1.
Identify the endocrine glands mentioned in the figure.
Answer:
Pituitary gland, Pineal gland, Thyroid gland, Parathyroid gland, Thymus gland, Adrenal gland, Pancreas,
Testes and Ovaries.

Bihar Board Class 10 Science Chapter 7 Control and Coordination NCERT Exemplar Problems

Short Answer Type Questions

Question 1.
Label the parts (a), (6), (c) and (d) and show the direction of flow of electrical signals in figure given below.
Answer:
(a) Sensory neuron,
(b) Spinal (CNS),
(c) Motor neuron,
(d) Effector = Muscle in arm.

Question 2.
Name the plant hormones responsible for the following :
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division .
(d) falling of senescent leaves.
Answer:
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscisic acid

Question 3.
Label the endocrine glands in the figure given below.
Answer:
(a) Pineal gland
(b) Pituitary gland
(c) Thyroid
(d) Thymus

Question 4.
In the figures given below (a), (b) and (c), which appears more accurate and why?

Answer:
Figure (a) is more appropriate because in a plant shoots are negatively geotropic hence, grow upwards and roots are positively geotropic so grow downwards.

Question 5.
Label the parts of a neuron in the figure given on the next page.

Answer:
(a) Dendrite
(b) Cell body
(c) Axon
(d) Nerve ending

Question 6.
Match the terms of Column (A) with those of –
(a) Olfactory receptors – (i) Tongue
(b) Tbermo’receptors  (temperature receptors) – (ii) Eye
(c) Gustatoreceptors – (iii) Nose
(d) Photoreceptor’s – (iv) Skin
Answer:
(a) → (iii)
(b) → (iv)
(c) → (i)
(d) → (ii)

Question 7.
What is a tropic movement? Explain with an example.
Answer:
The directional grow th movements of plants due to external stimuli are called 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.

Question 8.
What will happen if intake of iodine in our diet is low?
Answer:
When iodine intake is low, release of thyroxin from thyroid gland will be less by which protein, carbohydrate and fat metabolisms will be affected. Besides, a person might suffer from goitre in case of iodine deficiency in the body.

Question 9.
What happens at the synapse between two neurons?
Answer:
When an electrical signal reaches the axonal end of one neuron it releases certain chemical substances that cross the synapse and move towards the dendritic end of next neuron generating, another electrical signal.

Question 10.
Answer the following :
(а) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?
Answer:
(a) Oestrogen
(b) Growth hormone
(c) Insulin
(d) Thyroxin

Question 11.
Answer the following :
(a) Name the endocrine gland associated with brain.
(b) Which gland secretes digestive enzymes as well as hormones.
(c) Name the endocrine gland associated with kidneys.
(d) Which endocrine gland is present in males but not in females?
Answer:
(a) Pituitary
(b) jphncreas
(c) Adrenal
(d) Testes

Long Answer Type Questions

Question 12.
What are the major parts of the brain? Mention the functions of different parts.-
Answer:
The major parts of the brain are :
Fore-brain, Mid brain and Hind brain.

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 this, 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, for example, opr leg muscles. However, certain sensations are distinct fropi seeing or hearing.

Many the involuntary actions like blood pressure, salivation and vomiting, etc. are controlled by the mid-brain and hind¬brain. The mid-brain receives and integrates visual tactile and auditory inputs. The hind-brain comprises pons, cerebellum and medulla. Activities like walking in a straight line, riding a bicycle, picking up a pencil, etc. are possible due to a cerebellum. It is responsible for precision of voluntary actions and maintaining the posture and balance of the body. The medulla contains centres, which control respiration, Cardiovascular reflexes and gastric secretions. Pons consist of fibre tracts that inter-connect different regions of the brain.

Question 13.
What constitutes the central and peripheral nervous systems? How are the components of central nervous system prptected?
Answer:
The brain and the spinal cord constitute our central and peripheral nervous systems. A delicate organ like the brain, which is so important for a variety of activities, needs to be carefully protected. For this, our body is so designed that the brain sits inside a bony box. Inside the box, the brain is contained in a fluid filled balloon which provides further shock absorption. The vertebral column or back-bone present in the middle of our back, protects the spinal cord.

Question 14.
Mention one function for each of these hormones :
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone.
Answer:
(a) Thyroxin regulates carbohy-drate, fat and protein metabolisms
(b) Insulin – regulates blood sugar
(c) Adrenaline – increases heart rate and supply of blood to various organs
(d) Growth hormone – regulates growth and development
(e) Testosterone – controls the changes of body features associated with puberty in male.

Question 15.
Name various plant hormones. Also give their phy-siological effects on plant growth and development.
Answer:
Some of the hormones released by different plant parts are :
auxins, gibberellins, cytokinins, abscisic acid and ethylene.

Effects of these hormones on plant growth and development :

• Auxins : They promote cell elongation, root formation, cell division, etc. They also promote fruit growth.
• Gibberellins : They stimulate stem elongation, seed germination and flowering.
• Cytokinins : They help in breaking the dormancy of seeds and buds. They delay ageing in leaves. They promote the opening of stomata.
• Abscisic acid It promotes falling of leaves and fruits.
• Ethylene : It promotes ripening of fruits. –

Question 16.
How does chemical coordination take place in animals?
Answer:
Chemical coordination takes place in animals with the help of some chemical substances called hormones. Different endocrine glands secrete different hormones. These hormones are released into blood which carry them to specific tissues or organs called target tissues or target organs. In the target tissues, hormone triggers a particular biochemical or physiological activity. The timing and amount of hormone released are regulated by feed back mechanism.

Question 17.
Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?
Answer:
When an electrical signal reaches the axonal end of a . neuron, it releases a chemical substance. This chemical diffuses towards the dendrite end of next neuron where it generates an electrical impulse or signal. Hence, the electrical signal is converted into a chemical signal at the axonal end. Since these r chemicals are absent at the dendrite end of the neuron the electrical signal, cknnot be converted into chemical signal. That is why the flow of, signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse.