HBSE 10th Class Science Important Questions Chapter 7 Control and Coordination

Haryana State Board HBSE 10th Class Science Important Questions Chapter 7 Control and Coordination Important Questions and Answers.

Haryana Board 10th Class Science Important Questions Chapter 7 Control and Coordination

Question 1.
What is the importance of control and co-ordination?
Answer:
1. Multicellular organisms are made-up of various organs and organ system.
2. It is a basic need of the body to control and co-ordinate these organs and organ systems, so that they can function properly and accomplish the voluntary as well as involuntary functions.

Question 2.
What is a stimulus?
Stimulus:
1. An event that encourages an action or creates sensation is called a stimulus. (Plural : Stimuli)
2. All living organisms — humans, plants and animals respond to changes occurring in their surroundings. These changes work as stimuli.
Example:

• On seeing sudden bright sunlight, our eyes gets closed. Here, the sudden bright light is stimulus whereas closing of eyes is response.
• If someone pours hot or cold water on us, we can feel it and also differentiate the temperature of water.
• A sunflower always faces the sun.
• Thus, heat, light, touch, weather changes, sound, etc. all are examples of external stimuli.
• If we are hungry, we feel like eating. Thus hunger, thirst, etc. are internal stimuli of the body.

Question 3.
What are receptors? Name few receptors found in human body, their location and function.
Answer:
Receptors:
1. A specialized structure in the human body that receives external stimuli is called a receptor.
2. These receptors are located in our sense organs. The main ones are —

Example	Location	Function
1. Gustatory receptors 2. Olfactory receptors 3. Thigmo receptors 4. Photo receptors 5. Audio (phono) receptors	On the surface of the tongue Nasal epithelium In the skin In the eyes In the internal ear	To detect taste To detect smell To detect touch To detect vision To detect sound

Question 4.
What is a nerve cell? Explain its structure, function and working.
Answer:
Nerve cell:
Nerve cells or neurons are the building as well as functional units of the nervous system. They carry information from one part of the body to another.
Nerve cell has three components:
(i) Cell body,
(ii) Dendrites and
(iii) Axon
(i) Cell body: The cell body of a neuron is like a typical animal cell which contains cytoplasm and a nucleus.
A number of short or long fibers stretch out from the cell body. These fibers are called nerve fibers.
(ii) Dendrites: The short fibers on the cell body are known as dendrites.
(iii) Axon: The longest fiber on the cell body is called axon.

Movement of Impulse (working of nerve cell):
1. The end of the dendritic tip receives message from receptors. It then initiates a neuro-chemical reaction due to which an electric impulse known as nerve impulse is produced.
2. The dendrites pass the impulse to the cell body and then to axon upto the end of axon i.e. axon terminal bud.
3. Synapse — The gap between nerve ending of an axon of one neuron and dendrite of the next neuron is called synapse.
4. At the end of the axon terminal bud, the electrical impulse releases certain chemicals.
5. These chemicals cross the gap or synapse and start similar electrical impulse in the dendrite of the next neuron. This is how the impulse or message travels from one neuron to another in the body.
6. Finally with the help of similar synapse, the impulses are delivered from neurons to other cells such as muscle cells or glands.

Question 5.
What happens at the synapse between two neurons?
Answer:
Nerve cell: Nerve cells or neurons are the building as well as functional units of the nervous system. They carry information from one part of the body to another.
Nerve cell has three components:
(i) Cell body,
(ii) Dendrites and
(iii) Axon
(i) Cell body: The cell body of a neuron is like a typical animal cell which contains cytoplasm and a nucleus.
A number of short or long fibers stretch out from the cell body. These fibers are called nerve fibers.
(ii) Dendrites: The short fibers on the cell body are known as dendrites.
(iii) Axon: The longest fiber on the cell body is called axon.

Question 6.
What is a nervous tissue? What does It specialize in?
Answer:
1. Nervous tissue is made up of organized network of nerve cells or say neurons.
2. Nervous tissue specializes in conducting messages through electrical impulses from one part of the body to another.

Question 7.
Identify the parts of a neuron in a diagram: (1) where information is acquired, (2) through which information travels as an electrical impulse, and (3) where these impulse must be converted Into a chemical signal for onward transmission.
Answer:
Parts of a neuron: a — nucleus, b — cell body, c — dendrite, d — axon, e — nerve ending.

(1) Information is acquired at the end of the dendrite tip (c) of the nerve cell.
(2) Information travels as an electrical impulse through dendrite, cell impulse through dendrite, cell body and along the axon (d) to its end (e).
(3) At synapse, this impulse gets converted into a chemical signal for onward transmission.

Question 8.
Explain reflex action.
Answer:
Reflex action:

• Reflex action is an involuntary and instant response of the muscles or glands to a stimulus. It takes place without involving the brain.
• Reflex action is an automatic process. It is the simplest form of response in nervous system.

Example:
(1) We immediately pull-back our hands when we suddenly touch a hot vessel or when someone pricks us a pin.
→ In such cases, we react or say respond before the message can reach our brain. Such a response is called reflex action.
(2) Knee jerk response,
(3) Coughing,
(4) Blinking eyes,
(5) Yawning, movement of diaphragm,
(6) Contraction of pupil,
(7) Sneezing,
(8) Mouth watering or looking or smelling favourite food, etc. are other examples.

Question 9.
What role does reflex action plays when we suddenly see a bright light or when we cough?
Answer:
1. When we suddenly see a bright light, pupil of our eyes becomes small and it takes some time for the eyes to adjust to the bright light. In this case, reflex action protects the retina from damage that can be caused due to sudden and excessive light.
2. Coughing is another example in which reflex action does the job of clearing our wind pipe.

Question 10.
Explain reflex arc.
Answer:
Reflex arc:

• The pathway or say the route taken by the nerve impulses in a reflex action is known as the reflex arc.
• Reflex arcs allow rapid response.

Example:
1. A reflex action is an automatic response to a stimulus. So, when we suddenly touch a hot plate (a stimulus) we quickly, without thinking pull our hand back.
2. This type of very quick and automatic response is called reflex action.
3. The diagram shows the pathway taken by the nerve impulses in this reflex action.

• The heat is sensed by thermoreceptor in our hand.
• The receptor fingers an impulse in a sensory neuron which transmits the information to the spinal cord.
• From spinal cord, the impulse is passed to a relay neuron which in turn passes it to a motor neuron.
  Relay neurons are the communicating neurons between the sensory and motor neurons.
• The motor neuron transmits the impulse to the muscle of the arm. The muscle then contracts and pulls the hand away from the hot plate.
• The muscle of arm is an effector because it responds to the stimulus.
  This pathway along which the impulse travels is called the reflex arc.

Question 11.
Reflex actions have also evolved in animals. Explain.
Answer:
1. Generally, animals do not possess the complex neuron network needed for thinking. If at all they possess, the network is very basic. This means that animals cannot think as fast as humans.
2. However, they do need to respond to several sudden situations such as attack from other animals. To tackle such situations, the reflexes of animals are quite evolved.

Question 12.
How do Involuntary actions and reflex actions differ from each other?
Answer:

Reflex action	Involuntary actions
Reflex actions are very quick.	Involuntary actions are not that quick.
Reflex action can involve any muscle or gland.	Involuntary actions can involve only smooth muscles and cardiac muscles.
Reflex actions not initiated by brain.	Generally, involuntary actions involves brain.
It occurs suddenly in response to some external stimuli, For example, pulling away hand when it touches a hot vessel.	It does not need any external stimuli, It can go on continuously under normal conditions. For example, heartbeats, breathing, etc.

Question 13.
How does control and co-ordination take place in humans? Also, explain the functions of nervous system.
Answer:
There are two systems which co-ordinate different activities In humans:
(A) Nervous system and (B) Endocrine system (or Hormonal system)
These two systems work together to control and co-ordinate all our activities such as physical,emotional behaviour and thinking processes.

(A) Nervous system:

• It controls and co-ordinates all the parts of the body.
• The nervous system co-ordinates voluntary muscles, thus allowing a person to perform activities such as dancing, reading, writing, etc.
• The nervous system also co-ordinates certain involuntary functions like heart beat and breathing.
• The nervous system collects the information from the surrounding, interprets it and then responds accordingly.
• The nervous system also passes information from one system to other system.
• The units that make up the nervous system are called nerve cells or neurons. Thus, nerve cells are the functional units of a nervous system.

(B) Endocrine system (or Hormonal system):

• There are certain glands in the endocrine system which release chemical substances (chemical messengers) called hormones in the body.
• Generally, hormones regulate the slow activities of the body such as growth, metabolism, etc.
• The hormones are secreted in a small quantity and reach to the target organ by blood. Generally hormones do not travel long.

Question 14.
State the organization of human nervous system.
Answer:
Organs of Human Nervous System:

• The Central Nervous System of a human being is one of the important parts of the control and co-ordination system of the body.
• The Peripheral Nervous System does the task of establishing communication between the central nervous system and the other parts of the body.

Question 15.
Explain the structure and functioning of human brain along with a diagram.
Answer:
Human brain is divided into three major parts:
(i) Fore brain,
(ii) Mid brain and
(iii) Hind brain.

(I) Fore brain :

• 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 specialized for hearing, smell, sight, etc.
• There are other separate areas 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. Finally, a decision is made by the brain considering all the information it gathers.

(ii) Midbrain:

• Mid brain connects the forebrain and hind brain.
•  It is the centre for visual and auditory reflexes.

(iii) Hind brain:

• Hind brain consists of three regions: (A) Cerebellum which lies on dorsal side and (B) Pons and (c) Medulla oblongata.
• It controls involuntary activities like breathing, heart-beat, blood pressure, peristaltic movements, etc.

Question 16.
How is the central nervous system protected? OR How is the brain protected from external injuries? OR How are the delicate organs of human nervous system protected? OR Give reason: The central nervous system is well protected.
Answer:
1. The central nervous system (CNS) consists of the brain and spinal cord.
2. The brain is protected by an extremely hard bony-box called cranium (skull). The skull envelopes the brain.
3. Inside the skull, the brain lies within the cerebro-spinal fluid-filled balloon-like structure which provides cushioning and works as a shock absorber.
4. The spinal cord is protected in a hard skeletal structure called a vertebral column or backbone.

Question 17.
How does the nervous tissue cause an action?
Answer:
(a) Role of nervous tissue in causing the action:

• The neurons receive the stimuli from the surroundings with the help of sensory organs namely eyes, ears, nose, tongue and skin.
• Then the information is sent to the central nervous system (mostly to the brain).
• The brain analyzes the stimulus and makes the decision about what has to be done. According to this, the order is formulated. Now this decision order is sent to the related muscles through the neurons.
• Finally, the muscles act accordingly and thus the whole action response takes place.

(b) Role of muscle tissue in causing the action:

• When a nerve impulse reaches the muscle, the muscle fibre moves. This movement starts at the cell level.
• The muscle cells will move by changing their shape so that they can become short.
• The musde cells have special proteins that change their shape as well as their at angement in the cell in response to the nerve impulses. When this happen, the proteins get arranged in a different manner and hence muscle movement takes place.
• This movement of muscle is known as voluntary movement of muscle.

Question 18.
Write a note on movement of voluntary muscles.
Answer:
Role of muscle tissue in causing the action:

• When a nerve impulse reaches the muscle, the muscle fibre moves. This movement starts at the cell level.
• The muscle cells will move by changing their shape so that they can become short.
• The musde cells have special proteins that change their shape as well as their at angement in the cell in response to the nerve impulses. When this happen, the proteins get arranged in a different manner and hence muscle movement takes place.
• This movement of muscle is known as voluntary movement of muscle.

Question 19.
Explain plant movement In brief.
Answer:
Plant movement:

• Plants remain fixed at a place with their roots in the ground and so they cannot move from one place to another.
• However, movement of individual parts of a plant such as root, leaves, etc. is possible when they are subjected to some external stimuli like sunlight, gravitational force, water, touch, etc. Such movements of plants are called plant movements.
• The plant movement with respect to external stimuli falls into two main categories: (I) Tropism and (II) Nastism.

Question 20.
Explain “Plants show two different kinds of movements”. OR State and explain briefly the types of movements in plants.
Answer:
The movement of plants can be classified into two types. They are:
(1) Growth dependant movement:
→ When seeds are planted, they sprout as a plant and grow taller with time. This is directional movement.
(2) Growth independent movement.

Question 21.
How is co-ordination in plants different from co-ordination in animals? OR Plants co-ordinate slowly as compared to animals. OR Give scientific reason — “In general, the plants cannot respond to stimulus quickly”.
Answer:
1. The change in the environment to which the organisms respond and react is called stimulus (Plural: stimuli). Animals possess nervous system as well as hormones for co-ordinating their activities whereas plants have only hormones for responding to stimulus.
2. Animals have sense organs such as nose, ears and eyes which help them sense things and activities faster.
3. Plants too are capable to sense the effect of gravity, light, water, chemicals and touch but only by the means of their hormones.
4. Thus, plants identify all these environmental changes only with the help of their hormones. So, since plants are devoid of nervous system. they cannot respond to stimulus quickly.

Question 22.
How do some plants respond immediately on touching? Give an example. OR How do sensitive plants detect the touch and show movement?
Answer:
1. Generally, when we touch the plants (like chhui-mui or lajamani), they use electrical or chemical means to convey this information from cell to cell.
2. Here, the cells of plants change their shape by changing the amount of water in them. As a result, the cells may swell-up or shrink. Consequently. the shape of the cell gets changed.
Example:
When we touch the leaves of a chhui-mui (= Lajamani) plant i.e. a sensitive’ or ‘touch-me-not’ plant of mimosa family, it immediately begins to fold-up and droop.

Question 23.
What are tendrils? Explain. OR Explain the movement in the pea plant due to growth.
Answer:
1. In some plants, -a special thread like part arise from various parts of the plant, which are known as tendrils.
2. Such tendrils are highly sensitive to touch. When the thread structure comes in contact of any hard-support, it twists to it and starts growing in that specific direction.
3. Such type of plants are called climbers (t). For example, pea plant.
4. Because this growth is directional, it appears as if the plant is moving.

Question 24.
(a) What is meant by tropism? Explain with example.
(b) Mention the types of tropism. Explain each one in detail.
Answer:
(A) Tropism (Tropic movement) :

• It the growth movement (response) in a plant organ is due to the effect of an external and directional stimuli, then it is called tropism or tropic movement.
• It the plant shows growth in the direction of the stimulus, then it is called positive tropism whereas if the plant shows growth away from the stimulus, it is called negative tropism.
• Plants show movement with respect to five stimuli.

(B) Types of tropism:

Stimulus	Type of tropism the stimulus causes and its details
1. Light	Photoperiodism: Movement of plant growth in response to light is calledphotoperiodism. Stems respond to light and bend towards it. This is called positive photoperiodism shown by stem. Roots of plants bend away from light. This is called negative photoperiodism shown by roots
2. Gravity	Geotropism: Movement of plant growth in response to gravity is called geotropism. Stem always grow away from gravity of earth i.e. stems show negative geotropism while root always grow towards the gravity of earth i.e. roots show positive geotropism
3. Chemical	Chemotropism: Movement of plant growth in response to a chemicalstimulus is called chemotropism. For example, the growth of pollen tube in the downward direction towards ovule during the process of fertilization.
4. Water	Hydrotropism: The movement of a plant growth part in response to water is known as hydrotropism. For example, the roots of plant always grow towards the water. Thus, roots show positive hydrotropism.
5. Touch	Thigmotropism: The directional movement of a plant growth in response to touch is called thigmotropism. For example, ‘Touch me not’ plant close leaves themselves when touched.

Question 25.
What is the difference between photo nasty and thermonasty?
Answer:
Photonasty is a movement of the plant in response to light, whereas thermonasty is a movement of the plant in response to temperature. For example, flowers of sunflower and lotus open their petals in the morning when sunlight falls on them. Similarly, when temperature is increased, the crocus flower opens up.

Question 26.
What is chemical communication or hormonal co-ordination? Explain. OR What are hormones? Explain.
Answer:
1. One of the major limitations of nerve impulses is that they cannot reach each and every cell of animal body. Hence, there exists another means of communication which is called chemical communication or hormonal co-ordination.
2. Hormonal co-ordination takes place with the help of special chemical compounds called hormones.
The hormones are secreted by various glands of the endocrine system within the body.
3. Hormones are known as chemical co-ordinators or even chemical messengers.
4. Hormones are produced by a group of cells, get transported to a desired location and then act upon the cells of the target area simply by diffusion.
5. Although hormonal co-ordination takes place slowly, it can reach all the desired cells of the body.
6. Adrenaline, thyroxin, insulin, etc. are some of the hormones released in the body.

Question 27.
Describe plant hormones.
Plant hormone:
1. Plant hormones are special chemical compounds which are synthesized at one place/organ of the plants and migrate to the target organ to act. They play an important role in control and co ordination in plants, as well as in growth, development and responses to the environment.

Control and co-ordination in plants:

• Hormonal action is the main weapon to respond to various stimuli in the plants.
• Basically, there are two types of plant hormones. They are —

(A) Growth-promoting hormones:

(i) Auxins:

• It particularly acts on the areas of shoot-tip and root-ends, It helps the cells to grow longer.
• When light comes from one side of the plant. auxins diffuse towards the shady side of the shoot.
  The concentration of auxin stimulates the cells to grow longer on the shoot side, away from the light. Consequently, plants appears to bend towards light.

Gibberel lins:

• It helps in the growth of the cells and the stems.

Cytokinins:

• It is present in the higher concentration in the areas of the plants where rapid cell division occurs. For example, fruits and seeds.
• It promotes cell-division.

(B) Growth resisting / inhibitory hormones:

(i) Abscisic Acid (ABA):

•  It is responsible for wilting and falling of the leaves.
• It is responsible for the detachment of leaves, flowers and fruits.

Question 28.
Describe human endocrine system and give a list of glands in human body.
Answer:
1. Human nervous system and endocrine system work in the co-ordination with each other.
2. The endocrine system is the network of glands in the body. These glands release hormones.

Hormones:

• Basically, hormones are the chemical substances (chemical messengers).
• They play an important role in various metabolic processes.
• The hormones are secreted in a small quantity and reach to the target organ by blood. Generally, the target organ is nearby.

Glands: There are two types of glands.
They are — (1) Exocrine glands and (2) Endocrine glands.

Main endocrine glands of the human body

Question 29.
Give an idea about the hormones released by glands. Also state the main functions of these hormones.
Answer:

Gland	Hormone it releases	Function of the hormone
Adrenal	Adrenaline	Regulates heart-beat rate, breathing. blood pressure and carbohydrate metabolism. It plays an important role in fright, fight and flight.
Thyroid	Thyroxin	Thyroxin regulates carbohydrate, protein and fat metabolism in the body. This enables best balance for growth.
Pituitary	Growth hormone and many other hormones	Growth hormone regulates growth and development of the body. Also induces other glands
Testes (in males)	Testosterone	Development and functioning of male sex organs and to develop the secondary sexual characters such as body hair, muscle development, change in voice, etc
Ovaries (in females)	Estrogen and progesterone	Helps in fertilization of egg and development of secondary sexual characters such as breast enlargement, changes in physical body, etc.
Pancreas	Insulin	Helps in regulating blood sugar levels

Question 30.
Write a short note on adrenal gland. OR Which hormone is called fight or flIght hormone? State its effect on the body.
Answer:
Adrenal gland:
1. The adrenal gland releases a hormone called adrenaline. Adrenaline hormone is also called fight or flight (run-away) hormone.
2. This hormone is secreted directly into the blood and carried to different parts of the body.

Effects of adrenaline:

• When adrenaline is released the heart beats become fast and so, more oxygen gets supplied to our heart.
• The muscles around the small arteries of heart and other organs contract due to which the digestive system and skin receive less blood. This diverts the blood to our skeletal muscles.
• Moreover, the breathing rate increases due to contractions of the diaphragm and the rib muscles.
• All these responses together enable the animal and human body to be ready for dealing with the situation of fight or flight i.e. fight or run-away immediately from the situation.

Question 31.
Write a note on thyroid gland and the importance of the hormone It releases.
Answer:
Thyroid gland:
1. Thyroid gland secretes a hormone called thyroxin.
2. Thyroxin controls metabolism rate of carbohydrate, protein and fat.
3. Deficiency of iodine can cause deficiency of thyroxin in the body.
4. Deficiency of iodine in our diet results in hypothyroidism and enlargement of thyroid gland. This results into a disease called goiter.
5. Neck of people suffering from goiter becomes swollen.
6. Goiter can be prevented by consuming iodized salt i.e. salt containing iodine.

Question 32.
It is highly recommended to consume iodized salt on a daily basis. Give reason.
Answer:
Adrenal gland:
1. The adrenal gland releases a hormone called adrenaline. Adrenaline hormone is also called fight or flight (run-away) hormone.
2. This hormone is secreted directly into the blood and carried to different parts of the body.

Effects of adrenaline:

• When adrenaline is released the heart beats become fast and so, more oxygen gets supplied to our heart.
• The muscles around the small arteries of heart and other organs contract due to which the digestive system and skin receive less blood. This diverts the blood to our skeletal muscles.
• Moreover, the breathing rate increases due to contractions of the diaphragm and the rib muscles.
• All these responses together enable the animal and human body to be ready for dealing with the situation of fight or flight i.e. fight or run-away immediately from the situation.

Question 33.
Write a short note on pancreas.
Answer:
Pancreas:
1. Pancreas is an endocrine gland as well as an exocrine gland.
2. As an endocrine gland. it secretes insulin and glucagon which maintain sugar level in the blood.
3. If insulin is not secreted in proper amounts, the sugar level in blood rises causing many harmful effects.
4. When the sugar level in blood rise, it gets detected by the cells of the pancreas. The cells respond to this rise by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

Question 34.
How is hormone secretion regulated?
Answer:
1. Hormone secretion is regulated by the feedback mechanism. In general, a particular gland secretes a specific hormone.
2. The hormone reaches to the target organ and performs its function. when that specific function completed, there is no need of that hormone. so, the message reaches to the brain and the brain stops that gland to secrete the hormone further. this is how hormone secretion is regulated.

Question 35.
Giving response to a stimulus is the basic characteristic of every living organism. give reason.
Answer:
1. The creation of living organisms is such that all of them experience the effects of changes in the atmosphere that surrounds them.
2. These effects work as stimuli for the organisms and they respond by making some changes in their bodies.
3. Slow or fast, but the organism will respond to stimuli such as heat, cold, sound, touch, etc.
4. Thus, response to stimuli is the basic characteristic of every living organisms.

Question 36.
Label the parts of a neuron in the given figure.

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

Question 37.
We respond very quick to reflexes but very slow to the act of thinking. Give reason.
Answer:
1. Thinking is a complex activity and so it involves a complicated interaction of several nerve impulses that too from many neurons.
2. Thinking center is located in forebrain.
3. When this centre receives signals through sensory nerves from various parts of the body, it analyzes the signals and formulates the instructions. The instructions then transmit from brain to the target organ. This process takes some time and hence the response is slow.
4. In reflex action, initially the brain is not involved in decision making. So, the instruction is generally given by spinal cord before the message could reach the brain for analysis and decision making purpose. As a result, the decision making is quite quick.
5. Hence, we respond very quick to reflexes but very slow to the act of thinking.

Question 38.
Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in Figure.
Answer:
(a) Sensory neuron
(b) Spinal cord (CNG)
(c) Motor neuron
(d) Effector (muscle in arm)

Question 39.
Name the plant hormones responsible for the ………………
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves
Answer:
(a) Auxiri – elongation of cells
(b) Gibberellin – growth of stem
(c) Cytokinin – promotion of cell division
(d) Abscisic acid – falling of senescent leaves

Question 40.
Out figure (a), (b) and (c), which appears more accurate and why?
Answer:
Figure (a) is more appropriate.
Reason: In a plant, shoots are negatively geotropic and hence grow upwards and roots are positively geotropic and so grow downwards.

Question 41.
Why do multicellular organisms use hormonal system in addition to the nervous system? Multicellular organisms use hormonal system in addition to the nervous system due to following two reasons:
Answer:
1. The nervous system transmit electrical impulses. The electrical impulse can reach only those cells that are connected to the PNS.
2. Secondly, after the generation of the electrical impulses, the cell takes some time to reset or to normalize.
3. As a result, multicellular organisms use hormonal system in addition to the nervous system.

Question 42.
State the characteristics of animal hormones.
Answer:
Characteristics of animal hormones:
1. Hormones are chemical compounds secreted from specific endocrine glands.
2. Hormones are chemical co-ordinators and are also called chemical messengers.
3. Generally, they control slow activities of the body such as growth and metabolism.
4. They are synthesized at places away from where they need to act. They then travel to the target cells, tissues or organs and act by simple diffusion.
5. They are transported through blood.
6. They are secreted in very small quantities.

Question 43.
Give an idea about hormones related with growth in human.
Answer:
Mainly two hormones are related with growth in humans. They are —
(1) Growth hormone:

• It is secreted by the pituitary gland.
• Growth hormone regulates growth and development of the body.

(2) Thyroxln:

• It is secreted by thyroid gland.
• Thyroxin regulates carbohydrate, protein and fat metabolism in the body. This is necessary for balanced growth of body.

Question 44.
Which disorders can we face If hormonal balance gets disturbed?
Answer:
If hormones are secreted in inappropriate quantities, we may face the following disorders:
(1) Gigantlsm: It is caused due to excess secretion of growth hormone. Under this disorder, an individual becomes extremely tall.
(2) Dwarfism: Deficiency of growth hormone in childhood leads to dwarfism. Under this disorder, the height of an individual does not grow much and he remains dwarf-sized.

(3) Goiter: It is caused by the deficiency of iodine in our diet.

• Iodine deficiency affects the synthesis of thyroxin and causes goiter.
• The thyroid gland gets enlarged which results in enlargement of the neck region.

(4) Diabetes: If insulin hormone is not secreted in sufficient amounts, the sugar level rises in the blood. This causes diabetes.

Question 45.
A person suffering from diabetes is given the injections of insulin. Give reason.
Answer:
1. In human bodies, pancreas release a hormone called insulin which regulates the level of sugar in the blood.
2. When insulin is not secreted in proper amounts, the sugar level in the blood rises and the person may suffer from a disease called diabetes.
3. Diabetes can be harmful for heart, brain, eyes, kidneys, etc.
4. Hence, in order to save the diabetic person from such harmful effects, he is given the injections of insulin which regulates his sugar level in the blood.

Question 46.
Give differences between: Plant hormones and animal hormones
Answer:

Plant hormones	Animal hormones
1. Although plant hormones are secreted by plant cells there are no glands.	1. Animal hormones are secreted by endocrine glands
2. Plant hormones are either growth promoting or growth inhibiting.	2. Animals do not have inhibitor hormone for growth.
3. Plant hormones reach to their target site by simple diffusion.	3. AnimaI hormones reach to their target site by flowing along with blood.
4. Secretion of plant hormones is not regulated by feedback mechanism.	4. Secretion of animal hormones is regulated by feedback mechanism.

Question 47.
Label the endocrine glands shown In the figure. Also state their locations.

Answer:
The endocrine glands and its location are as follows:

Glands	Location
(a) Pineal gland	Attached to dorsal side of brain
(b) Pituitary gland	Just below the brain
(c) Thyroid	Attached to the windpipe
(d) Thymus	Lower part of the neck and
	upper part of chest

Question 48.
Differentiate between tropic movement and nastic movement.
Answer:

Tropic movement	Nastic movement
1. The movement of curvature in a plant organ due to the effect of an external and directional stimulus is called tropism. 2. Tropic movement is a directional movement. 3. Examples: Photoperiodism, geotropism, chemotropism, hydrotropism and thermotropism.	1. The movement of plant in response to an external stimulus in which the direction of response is not determined by the direction of stimulus is called nastic movement. 2. Nastic movement is not a directional movement. 3. Examples: Thigmonasty, photonasty and thermonasty.

Question 49.
Differentiate between response in plants and response in animals.
Answer:

Response in plants	Response in animals
1. Plants have only hormones for responding to stimulus. 2. Plants respond quite slowly. 3. Plants do not have sensory organs to respond to changes. 4. Plants do not have any muscular system for transfer of information.	1. Animals possess nervous system as well as hormones for co-ordinating their activities. 2. Animals respond quite quickly. 3. Animals have sensory organs to respond to changes. 4. Animals have well developed muscular system for transfer

Question 50.
Differentiate between movement of leaves of sensitive plants and movement of shoot towards light.
Answer:

Movement of leaves of sensitive plants	Movement of shoot towards light
1. It is a nastic movement which does not depend on the direction of stimulus. 2. Here the stimulus is ‘touch’. 3. This movement is caused when a plant is touched at the base which leads to sudden loss of water from that region. 4. This is not a growth movement.	1. It is a tropic movement which depends on the direction of stimulus. 2. Here the stimulus is light’. 3. This movement is caused by unequal growth of two sides of the shoot. 4. This is a growth movement.

Question 51.
Differentiate between central nervous system and Autonomous nervous system.
Answer:

Central nervous system	Autonomous nervous system.
1. It comprises of brain and spinal cord. 2. It regulates voluntary, involuntary and reflex actions. 3. It has no further sub-types.	1. It comprises of special network of nerve fibers. 2. It regulates involuntary activities only. 3. Sympathetic nervous system and para sympathetic nervous system are its two sub-types.

Question 52.
Differentiate between cerebrum and cerebellum.
Answer:

Cerebrum	Cerebellum
1. It is a major part of forebrain. 2. It is divided into four lobes. 3. It co-ordinates tasks like seeing, hearing, touch and smell, etc.	1. It is a major part of hindbrain. 2. No such division occurs. 3. It co-ordinates tasks of body movement such as walking, dancing, riding bicycle, etc.

Question 53.
Smita’s father was complaining about frequent urination, pain in legs and a frequent weight loss to Smite’s mother and she discussed the things with her daughter, Smita she when returned from her school. Listening to this, Smite said to her mother that her father should visit a doctor, who told her mother that her husband is having an elevated level of blood glucose. He should take care of his diet and should exercise regularly to maintain his normal glucose level. On the basis of given text, answer the following questions.

Questions:
(1) Name the disease he is suffering from and name the hormone, whose deficiency causes it.
(2) Identify the gland that secretes it and mention the function of this hormone.
(3) Explain, how the time and amount of secretion of this hormone is regulated in human system?
(4) What values were shown by Smita and her father’?
Answers:
(1) Smita’s father is suflenng from diabetes. It Is caused by the deficiency of insulin hormone in the body.
(2) Pancreas secretes insulin. Insulin helps in regulating the sugar level in the blood.
(3) When the level of sugar increases in the blood, the body responds by producing more insulin. When blood sugar level falls, secretion of insulin gets reduced.
(4) The values shown by Smita are empathy and alertness in decision making. The values shown by her father are neglecting his health.

Question 54.
On a beautiful sunny day, Pritesh was in a beautiful mood f ride. His father was equally keen and both of them rode on his motorcycle. As soon as they reached the main cross road, they saw a tragic accident of a motorcycle with a car. The rider was not wearing helmet. So, on getting hit, the rider of the motorcycle fell and was again hit by the road divider. Crowd gathered and the rider was immediately shifted to the nearby hospital through an ambulance. Prltesh’s father looked at Pritesh with utmost anger and merciful state at the same time because Pritesh too was not wearing the helmet and he too could meet such an accident.

Questions:
(1) Which part of brain is involved when you are learning to drive a vehicle?
(2) Injury to which part of brain leads to instant death of an individual? Why?
(3) Pritesh became quite fearful. Which gland do you think became more active when he saw the accident? Which hormone was poured in blood? What changes he might have felt in his body?
(4) Which values did Pritesh’s father displayed?
Answers:
(1) Cerebrum and cerebellum are involved while learning to ride.
(2) Injury to medulla oblongata in the brain leads to instant death. This is because all the involuntary activities are controlled by It.
(3) Seeing such an event, the adrenal gland of Pritesh must have become active. As a result. adrenaline hormone must have secreted in blood. Under such situation, Pritesh perspired and his heartbeats and breathing rate increased.
(4) Pritesh’s father showed the value of empathy and respecting one’s life because it is extremely precious. Moreover, he also showed the value of concern of a father for the son.

Question 55.
After studying chapter Control and Co-ordination, you learnt that probably your maid is suffering from one of the diseases discussed in that chapter. The front portion of her neck was bulged out abnormally. On discussing with her you also found that she faced difficulty in breathing and even swallowing food. Now, look at the questions given here and answer them.

Questions:
(1) From which disease do you think your maid is suffering?
(2) What is the main cause of this disease?
(3) How can you help her at an immediate basis?
(4) What values did you display here?
Answers:
(1) The symptoms show that she is suffering from goiter.
(2) Goiter is mainly caused due to deficiency of iodine.
(3) On an immediate basis we can provide her with iodine supplements as well as recommend her to use only iodized salt in her food.
(4) The values of alertness, caring and sound decision making are displayed here.

Question 56.
There are three plants A, B and C. The flowers of plant A open their petals in bright light during the day but close them when it gets dark at night. On the other hand, the flowers of plants B open their petals at night but close them during the day when there is bright light. The leaves of plant C fold up when touched with fingers or any other solid object.

(a) Name the phenomenon shown by the flowers of (j) plant A, and (ii) plant B.
(b) Name one flower each which behaves like the flower of (i) plant A, and (ii) plant B.
(c) Name the phenomenon exhibited by the leaves of plant C.
(d) Name a plant whose leaves behave like those of plant C.
(e) Which plant(s) exhibit phenomenon based on growth movement?
Answer:
(a) (i) Photonasty (ii) Photonasty
(b) (i) Dandelion flower (ii) Moonflower
(c) Thigmonasty
(d) Sensitive plant (Mimosa pudica)
(e) A and B

Very Short Answer Type Question

Question 1.
Which two body systems are important in control and co-ordination?
Answer:
Hormonal system (= Endocrine system) and Nervous system.

Question 2.
Name main components of a neuron.
Answer:
Dendrites, Cell body and Axon.

Question 3.
What Is the function of dendrite?
Answer:
It carries nerve impulses which has been received from the axis of the previous neuron towards the cell-body of a neuron.

Question 4.
What is the role of axon?
Answer:
It carries nerve impulses from the cell body towards next neuron’s dendrite or tissue.

Question 5.
Define stimuli.
Answer:
An event that encourages the action or creates sensation is called stimulus. (Plural = Stimuli)

Question 6.
Define Response.
Answer:
The reaction of living organisms against the stimulus induced by the change in the external environment is called response.

Question 7.
Define Co-ordination.
Answer:
Different organs of the body jointly function systematically against the stimuli and react to express proper response against the stimuli. This process is called coordination.

Question 8.
What is a spinal cord? What ¡s its function?
Answer:
Spinal cord is a cylindrical structure which is the extension of medulla oblongata. Spinal cord is a part of Central Nervous System (CNS).

Question 9.
State the function of spinal cord.
Answer:
(i) To conduct sensory information from peripheral nervous system to the brain.
(ii) To conduct motor information from brain to various effectors.

Question 10.
Reflex arc of some animals is much evolved. Why?
Answer:
Because thinking process of the brain of these animals is not so fast. So, the evolved reflex arc serves as an efficient way of performing various functions.

Question 11.
How do we feel that we have eaten enough?
Answer:
The centre of hunger and satiety are located in a separate part of the fore-brain. They give the feeling of being hungry or satisfied.

Question 12.
Name the most important part of the human brain.
Answer:
Cerebrum

Question 13.
State one function each of cerebellum and Pons.
Answer:
Cerebellum maintains balance of body and posture. Pons regulates respiration.

Question 14.
Give the functions of medulla oblongata.
Answer:
Medulla oblongata controls involuntary functions such as breathing, heart beats, digestion, blood pressure, pristaltic movements of alimentary canal, etc, It also controls reflexes such as coughing, sneezing, swallowing, secretion of saliva and vomiting.

Question 15.
What does CNS stand for?
Answer:
CNS is the abbreviation for Central Nervous System.

Question 16.
Which is the most important part of the human brain?
Answer:
Cerebrum. It is also the largest part of the brain.

Question 17.
State two examples of movement that we make for protecting ourselves.
Answer:
(1) When we suddenly see bright light, we compress our pupils.
(2) We pull back our hand when we touch a hot object.

Question 18.
What are the components of peripheral nervous system?
Answer:
Cranial nerves and spinal nerves

Question 19.
Why thinking Is considered a complex activity?
Answer:
Thinking involves a highly complex interaction of several nerve impulses from many neurons. Hence,……..

Question 20.
How does a muscle cell move?
Answer:
Muscle cells move by changing their shape i.e. either by shortening or elongating.

Question 21.
What are phytohormones?
Answer:
The chemical substances which help in control and co-ordination in plants are known as phytohormones.

Question 22.
Give examples of phytohormones.
Answer:
Auxins, Gibberellins, Cytokinins, Abscisic acid (ABA), Ethylene, etc.

Question 23.
What is photoperlodism?
Answer:
The developmental response of plants to the relative lengths of light and dark periods is known as photoperiodism.

Question 24.
What are the main types of a plant movement?
Answer:
(i) Growth dependant movement and
(ii) Growth independent movement

Question 25.
Name the plant which shows thigmonasty.
Answer:
Mimosa plant

Question 26.
Give an example of movement of a plant part which is caused by the loss of water.
Answer:
Thigmonastic movement as seen in mimosa plant.

Question 27.
What does a root do in response to gravity? What is this phenomenon known as?
Answer:
In response to gravity, the root grows towards the earth. This phenomenon is known as geotropism.

Question 28.
What does a stem do in response to light? What is this phenomenon known as?
Answer:
Stem bends towards the light. This phenomena is called phototropism. For stems, it is also called positive phototropism.

Question 29.
What does a stem do In response to gravity? What is this phenomenon known as?
Answer:
Stem always grows away from the earth i.e. away from gravity. This is called negative geotropism.

Question 30.
What does a root do in response to light? What Is this phenomenon known as?
Answer:
The roots of the plant bend away from the light.
This is called negative phototropism.

Question 31.
Name one hormone secreted by the pituitary gland.
Answer:
Thyroid Stimulating Hormone (TSH).

Question 32.
Where are hormones synthesized (made) in the human body?
Answer:
Hormones are made by specialized glands or tissues throughout the body. Most but not all hormones are part of endocrine system.

Question 33.
Which gland secretes the growth hormone ?
Answer:
Pituitary gland

Question 34.
Name the disease caused by the deficiency of insulin hormone in the body.
Answer:
Diabetes

Question 35.
Why are hormones called chemical messengers?
Answer:
Hormones carry information in the form of chemicals which regulate the biological processes of body. Hence,………..

Question 36.
Why both, chemical signal and electrical impulses are needed in higher animals?
Answer:
In higher animals, electrical impulses bring immediate response to only those cells that are connected by nervous tissue while chemical
signals reach to each arid every cells of body. Hence, …..

Question 37.
Which mechanism is considered as a second way of control and co-ordination in our body?
Answer:
Secretion of hormones by the endocrine system is considered as a second way of control and co-ordination in our body.

Question 38.
Where is growth hormone auxin synthesized and where is it diffused?
Answer:
Auxin is synthesized at the shoot tip and is diffused at that side of the shoot which is in shade.

Question 39.
State the site of secretion as well as the function of growth hormone releasing factor.
Answer:
Site of secretion: Hypothalamus; Function: Stimulates the pituitary gland to release growth hormone.

Fill in the Blanks

1. ………… is the unit of human nervous system.
Answer:
neuron

2. The word ‘reflex’ means …………
Answer:
Sudden action

3. In a neuron, conversion of electrical signal to a chemical signal occurs at/in …………
Answer:
axonal end

4. The highest co-ordinating part …………
Answer:
brain

5. Aging process in the plants is phytochrome
Answer:
Cytokinins

6. …………  causes seed dormancy in plants.
Answer:
ABA

7. The main function of abscisic acid in plants is to …………
Answer:
inhibit growth

8. The substance that triggers the fall of mature leaves and fruits from plants is due to (hormone).
Answer:
abscisic acid

9. The plant movement with respect to external stimuli falls into two main categories which are ……… and ………..
Answer:
Tropism; Nastism

10. In comparison to animals, plants are devoid of …………  for coordinating activities.
Answer:
Nervous system

11. Growth of pollen tube is an example of …………
Answer:
Chemotroplsm

12. The auxin hormone acts particularly on and of …………  the plant body.
Answer:
Shoot; root

13. ………… is also known as a master gland.
Answer:
Pituitary gland

14. Iodine is necessary for the synthesis of …………  hormone.
Answer:
Thyroxln

15. Dwarfism results due to …………
Answer:
Less secretion of growth hormone

16. The hormone which increases the fertility in males is called …………
Answer:
testosterone

True Or False

1. Except unicellular organisms, all respond to stimuli. — False
2. We can feel touch due to thigmo receptors. — True
3. Both neurons and hormones can be considered as messengers. — True
4. Generally, the nervous system co-ordinates fast activities whereas endocrine system co ordinates slow activities. — True
5. Electrical impulses will reach only those cells which are connected by nervous tissue. — True
6. Mid brain is the centre for visual and auditory reflexes. — True
7. A nerve impulse makes the muscle move. — True
8. Generally, hormones travel far off in the body to deliver the message. — False
9. Plants show two types of movement. — True
10. Cytokinin is present in the higher concentration in the areas of the plants where rapid cell division occurs. — True
11. Pancreas maintains carbohydrate, protein and fat metabolism in the body. — False
12. Pancreas is an endocrine gland as well as an exocrine gland. — True

Match the Following 

Question 1.

Column-I	Column-II
A. Photoreceptor B. Phonoreceptor C. Olfactory receptor D. Gustatory receptor	p. Detects smell q. Detects light r. Detects taste s. Detects sound

Answer:
(A q), (B – s), (C – p), (D – r)

Question 2.

Column-I	Column-II
A. Bony protection of brain B. Membranous covers of brain C. Shock absorbing liquid surrounding the brain	p. Cerebrospinal fluid q. Cranium r. Meninges

Answer:
(A -q), (B – r), (C – p)

Question 3.

Column-I (Plant action)	Column-II (Phytochrome)
A. Promotes growth B. Promotes cell division C. Inhibits growth D. Promotes growth of tendril around support	p. GA q. Auxin r. ABA s. Cytokinin

Answer:
(A – q), (B – s), (C – r), (D – p)

Question 4.

Column-I	Column-II
A. Metabolism of various nutrients B. Iodized salt C. Acromegaly D. Contraction of uterine muscle during childbirth Vasoconstrictor	p.GH q. Oxytocin r. Glucocorticoid s. ADH t. Thyroxin u. Prolactin y. RH

Answer:
(A – r), (B – t), (C – p), (D – q) (E – s)