LAKHMIR SINGH AND MANJIT KAUR Solutions for Class 10 Biology Chapter 2 - Control and Coordination

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Chapter 2 - Control and Coordination Exercise 92

Solution 1
Phytohormones.
Solution 2
Abscisic acid is responsible for the wilting and falling of leaves in plants.
Solution 3
Auxin.
Solution 4
Auxin is made at the tip of the plant stem.
Solution 5
Mimosa pudica.
Solution 6
A plant hormone that promotes growth is Gibberellin and the hormone that inhibits growth is abscisic acid.
Solution 7
Thigmonastic movement in the leaves of touch-me-not plant is very quick and can be observed easily.
Solution 8
Phytohormones.
Solution 9
(a) Light.
(b) Gravity.
(c) Chemical.
(d) Water.
(e) Touch.

Solution 10
(a) Phototropism.

(b) Geotropism.

(c) Chemotropism.

(d) Hydrotropism.

(e) Thigmotropism.

Chapter 2 - Control and Coordination Exercise 93

Solution 11
Thigmonasty.
Solution 12
(a) Root.

(b) Stem.
Solution 13
(a) is not growth movement whereas (b) is growth movement.
Solution 14
(a) Root.
(b) Stem.

Solution 15
(a) Gravity.
(b) Light.

Solution 16
(a) Phototropism.

(b) Geotropism.

(c) Light.

(d) Gravity.

(e) Touch.

(f) Earth, gravity.

(g) Geotropism.

(h) Auxin.

(i) Photonasty.
Solution 17
(a) Bending of stem towards light.

(b) Folding up of leaves of a sensitive plant on touching.
Solution 18
The hormones that control and coordinate the activities in plants are called plant hormones.

The four types of plant hormones are:

(i) Auxins - It promotes cell enlargement and cell differentiation in plants.

(ii) Gibberellines - It helps in breaking the dormancy in seeds and buds.

(iii) Cytokinins - It promotes cell division in plants.

(iv) Abscisic acid - It promotes the dormancy in seeds and buds.
Solution 19
(a) Root bends downwards in the direction of gravity; positive geotropism.

(b) Stem bends towards the light; positive phototropism.
Solution 20
(a) Stem grows upward against the direction of gravity; negative geotropism.
(b) Root bends away from light; negative phototropism

Solution 21
(a) In Mimosa pudica plant, the leaves fold up in response to touch. This phenomenon is known as thigmonasty.
(b) (i) A dandelion flower opens up in the morning in bright light. This phenomenon is known is positive photonasty.
(ii) At night, the dandelion flower closes and this phenomenon is known as negative photonasty.

Solution 22
(a) The plant root grows towards water and the phenomenon is known as the hydrotropism.

(b) (i) During the daytime the petals of moon flower close when there is bright light.

(ii) At night, when it is dark the petals of moon flower opens up. This phenomenon is known as photonasty.
Solution 23
Tendrils are the thin, thread-like growths on the stems or leaves of climbing plants. The two types of tendrils are stem tendrils and leaf tendrils. The tendrils grow towards the things they happen to touch. This phenomenon is known as thigmotropism.

Solution 24
The five types of tropisms are: Phototropism, Geotropism, Chemotropism, Hydrotropism and Thigmotropism. The various types of tropic movements help the plants to survive.
Example even if a seed is planted upside down, its root will grow downwards into earth because it is positively geotropic.

Solution 25
The growth of a plant part due to chemical stimulus is known as chemotropism. For example the growth of pollen tube towards the ovule induced by a sugary substance as stimulus. This is an example of positive chemotropism.
Solution 26
Tropic movements Nastic movements
1. These movements are always in the direction of the stimulus.

2. These movements are slow.

3. These movements are exhibited by all parts of a plant. For example, movement of shoot towards the light and not towards gravity.
1. These movements are neither away nor towards the stimulus.

2. These movements are fast.

3. These movements are exhibited by the flat organs (like leaves and petals of flowers) of a plant. For example, the bending and drooping of leaves in 'Touch-me-not' plant.
Solution 27

(a) The movement of a plant part in response to an external stimulus in which the direction of response is not determined by the direction of stimulus is called nastic movement.
Example: The folding up of the leaves of a sensitive plant on touching is an example of thigmonasty.


(b)

Chapter 2 - Control and Coordination Exercise 94

Solution 28
(a) Figure (ii)

(b) Geotropism.
Solution 29
(a) Abscisic Acid

(b) Cytokinin

(c) Auxin

(d) Abscisic Acid
Solution 30
(a) Stem
(b) Root
(c) Stem
(d) Root

Solution 31
The folding of leaves of a sensitive plant is not a case of tropism (like thigmotropism) because in this case the direction of movement of leaves does not depend on the direction of stimulus (touch).
Solution 32
The closing of a dandelion flower at dusk (when it gets dark) is not a tropism because the direction of movement of petals of dandelion flower does not depend on the direction of stimulus (light).
Solution 33
(a) A growth movement ofa plant part in response to an external stimulus in which the direction of stimulus determines the direction of response is called tropism.

Example - The bending of plant stem towards light is an example of positive phototropism.

(b) Different types of tropisms are:

(i) Phototropism - The movement of a plant part in response to light is called phototropism. Its stimulus is light.

(ii) Geotropism - The movement of a plant part in response to gravity is called geotropism. Its stimulus is gravity.

(iii) Chemotropism - The movement of a plant part in response to a chemical stimulus is called chemotropism. Its stimulus is chemical.

(iv) Hydrotropism - The movement of a plant part in response to a water stimulus is called hydrotropism. Its stimulus is water.

(v) Thigmotropism - The movement of a plant part in response to a touch stimulus is called thigmotropism. Its stimulus is touch.

(c)

Tropisms Nasties
1. These movements are always in the direction of the stimulus.

2. These movements are slow.

3. These movements are exhibited by all parts of a plant. For example, movement of shoot towards the light and not towards
1. These movements are neither away nor towards the stimulus.

2. These movements are fast.

3. These movements are exhibited by the flat organs (like leaves and petals of flowers) of a plant. For example, the bending and dropping of leaves in 'Touch-me-not' plant.
Solution 35
(a) The movement of plant part in response to gravity is called geotropism.

Example - Roots grow towards gravity.

(b) If the plant part moves towards the direction of gravity, it is called positive geotropism.

Example - Roots.

If the plant part moves against the direction of the gravity it is negative geotropism.

Example - Stem



(c) Tendrils.
Solution 36
(a) The plants do not have a nervous system but they can sense things in the presence of stimuli such as light, touch, water etc. and respond to them by the action of hormones. Thus, the plants coordinate their behavior against environmental behavior by using organic chemicals called hormones. This is called chemical coordination. The hormones in plants coordinate their behavior by affecting the growth of a part of the plant resulting in the movement of that plant part in response to a stimulus. The control and coordination in animals takes place by both nervous system and hormones.

(b) (i) Light - Phototropism.

(ii) Gravity - Geotropism.

(iii) Chemical - Chemotropism.

(iv) Water - Hydrotropism.

(v) Touch - Thigmotropism.

(c) The movement of a plant part in response to water is called hydrotropism.

Example: The roots of a plant always go towards water, this is positive hydrotropism.

Solution 37

(a) The growth of a plant part in response to a stimulus is called positive tropism and if the growth of a plant part is away from the stimulus, then it is called negative tropism.
Example: The roots of a plant go towards earth in response to gravity is an example of positive geotropism whereas stem grows away from earth against gravity is an example of negative geotropism.
(b) The directional growth movement of a plant part in response to the touch of an object is called thigmotropism.
Example: Tendrils grow towards any support which they happen to touch and wind around it.
(c)

Tendrils grow towards a stimulus hence it is a directional movement which shows that it is a case of thigmotropism whereas, the folding of leaves in mimosa plant does not depend on the direction of stimulus (touch) which shows that it is an example of thigmonasty.

Chapter - Exercise

Solution
Solution
Solution

Chapter 2 - Control and Coordination Exercise 115

Solution 1
Nervous system and Endocrine system.
Solution 2
Central nervous system and Peripheral nervous system.
Solution 3
Reflex action.
Solution 4
Cell body, dendrites and axon.
Solution 5
(a) Dendrites.
(b) Axon.    

Solution 6
Cerebrum.
Solution 7
Cerebellum.
Solution 9
Growth hormone.
Solution 10
Endocrine glands.
Solution 11
Endocrine system.
Solution 12
Pituitary gland.
Solution 13
(a) Testosterone.
(b) Progesterone and oestrogen.

Solution 14
(a) Photoreceptors.
(b) Thermoreceptors.
(c) Phonoreceptors.
(d) Olfactory receptors.
(e) Gustatory receptors.

Solution 15
Diabetes.
Solution 16
Goitre.
Solution 17
Iodine.
Solution 18
The people having severe diabetes are treated by giving injections of insulin.
Solution 19
Feedback mechanism.
Solution 20
(a) Thyroid gland.
(b) Salivary glands.
(c) Pancreas.

Solution 21
Diet provides iodine for making thyroxine hormone which keeps the thyroid gland healthy.
Solution 22
Diabetes.
Solution 23
Nose and Tongue.
Solution 24
Retina.
Solution 25
Nervous system and endocrine system.
Solution 26
(a) Ductless gland.
(b) Hormone.

Solution 27
Brain and spinal cord.
Solution 28
(i) Knee jerk reflex.
(ii) Sneezing.
(iii) Coughing.

Solution 29
Because iodine is necessary for making thyroxine hormone.
Solution 30
Reflex action.
Solution 31
(a) Muscle; glands.

(b) Nervous; sensory; motor.

(c) Sensory.

(d) Motor.

Chapter 2 - Control and Coordination Exercise 116

Solution 32
(a) There are 5 sense organs: Eyes, ears, nose, tongue and skin.
(b) A receptor is a cell (or a group of cells) in a sense organ which is sensitive to a particular type of stimulus (or a particular type of change in the environment). Example: Photoreceptors and Phonoreceptors.
An effecter is the part of the body which can respond to the stimulus according to the instructions sent from the nervous system (spinal cord and brain).
Example: Muscles and glands.

Solution 33
(a) Spinal cord is a cylindrical structure which begins in continuation with medulla and extends downwards. Its function is the conduction of nerve impulses to and from the brain and it is concerned with spinal reflex actions.
(b) The medulla controls various involuntary actions such as heart beat, breathing, blood pressure and peristaltic movements of the elementary canal. It is also the controlling centre for reflexes such a swallowing, coughing, sneezing, secretion of saliva and vomiting.

Solution 34

(a) The three types of nerves which make up the peripheral nervous system are: spinal nerves, cranial nerves and visceral nerves.


(b)

(c) When the agarbatti burns, it produces vapours having a characteristic pleasant smell which is detected by the olfactory receptors present inside our nose. The action of smell of agarbatti or receptors sets off chemical reactions which generate electrical impulses. The sensory neurons carry these electric al impulses to the sensory area of fore brain called cerebrum. This makes us detect the smell of burning agarbatti.

Solution 35
(a) Hormones are made by endocrine glands.
(b) Receptors are the special cells present in our sense organs which detect all the information from our environment and feed it to the nervous system.
An effector responds to electrical impulses sent from the nervous system through motor nerves.

Solution 36
(a) (i) Thyroxine (ii) Parathromone (iii) Insulin (iv) Adrenaline.
(b) The function of testosterone hormone is to control the development of male sex organs and male features such as deeper voice, moustache, body hairs etc. The function of oestrogen is to control the development of female sex organs and female features such as feminine voice, soft skin and mammary glands.

Solution 37
(a) Hindbrain has 3 regions:
(i) Pons: It takes part in regulating respiration.
(ii) Cerebellum: It helps in maintaining posture and balance of the body. It enables us to make precise and accurate movements.
(iii) Medulla: The medulla controls various involuntary actions such as heart beat, breathing, blood pressure and peristaltic movements of the elementary canal. It is also the controlling centre for reflexes such a swallowing, coughing, sneezing, secretion of saliva and vomiting.
(b) Function of cerebrum: It is the main thinking part of the brain. It is the site of our faculties such as learning, reasoning, intelligence, personality and memory. All our thoughts, sensation, actions and movements are controlled by cerebrum.

Solution 38
(a) The 3 regions of human brain are (i) Forebrain (ii) Midbrain and (iii) Hindbrain.
(b) Cranium is a bony box in the skull in which the brain is present. Its function is to protect the brain.

Solution 39
(a) The chemical coordination in animals takes place through the actions of chemicals called hormones which are release directly into the blood and are carried by the blood circulatory system to other parts of the body. Hormones travel all over the body but affect only particular organs at particular places which are called target organs. The organs control and coordinate several functions of animal body such as growth, development, metabolism, behavior and secondary sexual characteristics, etc.

(b) Iodine is necessary for the thyroid gland to make thyroxine hormone which regulates the metabolism of carbohydrates, fats and proteins so as to produce the best balance for the growth. Iodised salt is advisable as it contains appropriate amounts of iodine compounds needed by the thyroid gland to make sufficient thyroxine hormone for the body and hence goitre disease can be prevented.
Solution 40
The function of insulin hormone is to lower the blood sugar level (or blood glucose level). People having severe diabetes are treated by giving injections of insulin.
Solution 41
Nervous System Endocrine System
It is a system to coordinate the activities of bodies. It helps all other system of our body to work together. It receives information from the surroundings, processes it, interprets it and then responds accordingly. It is a group of endocrine glands which produces various hormones that helps in coordinating the activities of our body. The hormones produced by the endocrine glands act as messengers between the nervous system and the organs of our body.
Solution 43
The endocrine gland present in the human body are:

(i) Pineal gland

(ii) Hypothalamus

(iii) Pituitary

(iv) Thyroid

(v) Parathyroid

(vi) Thymus

(vii) Pancreas

(viii) Adrenal glands

(ix) Testes (in males)

(x) Ovaries (in females).

Pancreas, testes and ovaries function as exocrine glands.
Solution 44
(i) d

(ii) c

(iii) e

(iv) a

(v) b

Solution 45
It is an example of reflex action. The stimulus here is drawing pin lying on the floor. The pain is sensed by the receptors in the skin which triggers and impulse in a sensory neuron and transmits the message to the spinal cord. The impulse is passed onto a relay neuron, which in turn, passes it to the motor neuron. The motor neuron passes the impulse to a muscle in the feet. The muscle then contracts and pulls our feet away from the drawing pin.
Solution 46
Puberty and adolescence are the results of sex glands in human beings. In males, testes make male sex hormones called testosterone which is associated with male puberty, which the boys attain an age of 13-14 years. In females the oestrogen hormone is responsible for all the changes associated with female puberty which the girl attains at an age of 10-12 years.
Solution 47
Neurons and other cells have a cell membrane, cytoplasm and a nucleus.

Solution 48
(a)

Receptor Effector

A receptor is a cell (or a group of cells) in a sense organ which is sensitive to a particular type of stimulus (or a particular type of change in the environment).

Example: Photoreceptors and Phonoreceptors.

An effector is the part of the body which can respond to the stimulus according to the instructions sent from the nervous system (spinal cord and brain).

Example: Muscles and glands.
(b)

Cerebrum Cerebellum
(i) It is a part of forebrain.

(ii) It is the main thinking part of the brain. All our thoughts, sensation, actions and movements are controlled by cerebrum.
(i) It is a part of hindbrain.

(ii) It helps in maintaining posture and balance of the body. It enables us to make precise and accurate movements.
Solution 49

Digestion is an involuntary action as it does not involve the thinking process and is performed unknowingly by our digestive system.
Solution 50
(i) CNS - Central nervous system.

(ii) (a) Cerebrum (b) Spinal cord.
Solution 51
(a) Adrenaline.
(b) Insulin.
(c) Testosterone.
(d) Oestrogen.

Chapter 2 - Control and Coordination Exercise 117

Solution 55
(a) (i) The function of the nervous system is to coordinate the activities of our body.

(ii) It helps all other systems of our body to work together.

(iii) It receives information from the surroundings, processes it, interprets it and then responds accordingly.

(b) The main organs of the nervous system are; brain, spinal cord and nerves.



(c) When the sense organ in our body is affected, it sends the message to the brain in the form of electrical impulses through the sensory neurons. The brain analyses this message and decides the action to be taken. The brain then sends out instructions to the muscles of the concerned body parts through motor nerves and the concerned body part acts accordingly.
Solution 56

(a) The unit which makes up the nervous system is called a neuron. 

(b) A microscopic gap between a pair of adjacent neurons over which nerve impulses pass when going from one neuron to the next is called a synapse. Synapse between two neurons acts as a one way valve which allows electrical impulses to pass in one direction only. This happens as follows: When an electrical impulse coming from the receptor reaches the end of the axon of sensory neuron, then the electrical impulse releases tiny amount of a chemical substance called neuro transmitter substance into the synapse between two adjacent neurons. This substance crosses the synapse and starts a similar electrical impulse in the dendrite of the next neuron. In this way, the electrical impulses passes from one neuron to the next across the synapse. 

Solution 57
(a) Nervous system and endocrine system.
(b) The central nervous system consists of the brain and spinal cord. The work of the CNS is to direct incoming messages to the motor neurons that are connected to the part of the body which will respond to a stimulus. It is involved in complicated responses where both (brain and spinal cord) work. It enables a person to give a more appropriate and more intelligent response to various situations.
(c) (i) The brain receives information carrying nerve impulses from all the sensory organs of the body.
(ii) It responds to the impulses brought in by sensory organs by sending its own instructions through motor nerves to the muscles and glands causing them to function accordingly.
(iii) It correlates the various stimuli from different sense organs and produces the most appropriate and intelligent response.
(iv) It coordinates the body activities so that the mechanisms and chemical reactions of the body work together efficiently.
(v) It stores information so that behavior can be modified according to the past experience.

Solution 58
(a) (i) Pituitary - Growth.

(ii) Thyroid - Thyroxine.

(iii) Pancreas - Insulin.

(iv) Adrenal - Adrenaline.

(v) Testes - Testosterone.

(b) The endocrine glands do not have ducts to secrete their hormones. They release hormones directly into the blood of a person and reach the concerned body part through the blood and act on it.

(c) Hypothalamus.

(d) The adrenaline hormone prepares our body to function at maximum efficiency during emergency situations like danger, anger etc. This adrenaline hormone increases our heartbeat, breathing rate, blood flow into muscles and causes liver to put more stored glucose into our blood. All these actions produce a lot of energy in our body and help us to cope up the emergency situations. Thus, when adrenaline is secreted in large amounts it prepares our body for action.

(e) Goitre - The neck of the person appears to be swollen due to the enlargement of thyroid gland located in the neck.
Solution 52
(a) Stimulus.

(b) Receptors (Olfactory).

(c) Effector (Salivary glands).
Solution 53

(a) Te structural and functional unit of nervous system is neuron.
(b)

(c) Autonomic nervous system means self governing nervous system. Its function is to control and regulate the functions of the internal organs of our body involuntarily.
(d) The voluntary nervous system is a system which helps us to take voluntary actions which are under the conscious control of the brain.
Example: If a student is getting late for school and sees his watch. He starts walking fast. In this process, the eyes see the time and send the information to the brain through the sensory nerves. The brain analyses the information and sends the instructions to walk faster to the muscle of our legs through the motor nerves. The muscles of the legs act accordingly and make the student walk faster.

Solution 54

(a) The rapid, automatic response to a stimulus which is not under the voluntary action of the brain is called reflex action.
Example: Moving our hand away on touching a hot plate.

(b) The pathway taken by the nerve impulses in our reflex action is called the reflex arc.