AP 10th Class Biology 6th Lesson Important Questions Control and Coordination

These AP 10th Class Biology Important Questions 6th Lesson Control and Coordination will help students prepare well for the exams.

AP 10th Class Biology 6th Lesson Control and Coordination Important Questions

Class 10 Biology Chapter 6 Important Questions – 1 Mark

Question 1.
Which system controls control and coordination in our body ?
Answer:
For the control and coordination our body has two systems

• nervous coordination.
• chemical coordination.

Question 2.
Which receptors find taste and smell ?
Answer:
Gustatory receptors will detect taste while olfactory receptors will detect smell.

Question 3.
What is the reflex ?
Answer:
Without thinking about it, or without feeling in control of our reactions are called reflexes.

Question 4.
How the spinal cord is made up of ?
Answer:
Spinal cord is made up of nerves, which supply information to think about to the brain.

Question 5.
What are the major parts of the brain ?
Answer:
The brain has three such major parts or regions, namely the fore-brain, midbrain and hind-brain.

Question 6.
What are the movements in plants ?
Answer:
Plants show two different types of movements – one dependent on growth and the other independent of growth.

Question 7.
What is the primary plant hormone responsible for promoting cell elongation and growth ?
Answer:
Auxin.

Question 8.
Which plant movement is a response to touch or mechanical stimulation ?
Answer:
Thigmotropism.

Question 9.
Name the plant hormone responsible for promoting fruit ripening.
Answer:
Ethylene

Question 10.
What is the role of gibberellins in plants ?
Answer:
Gibberellins promote stem elongation, seed germination and flowering.

Question 11.
Which plant movement occurs in response to the force of gravity ?
Answer:
Gravitropism or geotropism. It scenes in the roots.

Question 12.
Identify the hormone responsible for closing stomata in plants.
Answer:
The hormone responsible for closing stomata in plants is Abscisic acid (ABA).

Question 13.
What is the significance of phototropism in plants ?
Answer:
Phototropism allows plants to grow towards a light source, optimizing photosynthesis

Question 14.
Name the growth movement in response to light.
Answer:
Phototropism

Question 15.
Which plant hormone is associated with the prevention of premature leaf senescence ?
Answer:
Cytokinin.

Question 16.
In what plant organ is abscisic acid (ABA) primarily synthesized ?
Answer:
Abscisic acid (ABA) primarily synthesized in Leaves.

Question 17.
Define coordination in animals.
Answer:
Coordination in animals refers to the harmonious functioning of different organs and systems to ensure proper response to stimuli and maintain internal balance.

Question 18.
What is the primary organ responsible for coordination in vertebrates ?
Answer:
The brain is the primary organ responsible for coordination in vertebrates.

Question 19.
Name the neurbtransmitter responsible for transmitting signals between nerve cells.
Answer:
The neurotransmitter responsible for transmitting signals between nerve cells is acetylcholine.

Question 20.
What is a reflex action ?
Answer:
A reflex action is an involuntary and rapid response to a stimulus, controlled by the spinal cord, bypassing the brain.

Question 21.
Give an example of a sensory receptor in animals.
Answer:
An example of a sensory receptor in animals is the photoreceptor in the eyes, responsible for detecting light.

Question 22.
Which part of the brain is responsible for the coordination of voluntary muscle movements ?
Answer:
The cerebellum is responsible for the coordination of voluntary muscle movements.

Question 23.
What is the role of hormones in coordination in animals ?
Answer:
Hormones act as chemical messengers and play a role in long-distance coordination in animals by regulating various physiological processes.

Question 24.
Define the term “homeostasis.”
Answer:
Homeostasis is the maintenance of a stable internal environment within an organism, despite external changes, to ensure optimal physiological functioning.

Question 25.
Name the part of the neuron that conducts impulses away from the cell body.
Answer:
The axon is the part of the neuron that conducts impulses away from the cell body.

Question 26.
What is the significance of the endocrine system in coordination?
Answer:
The endocrine system regulates various physiological processes by releasing hormones into the bloodstream, contributing to coordination in animals.

Question 27.
What is the pathway in the reflex arc ?
Answer:
The sequence of the components of a reflex arc is
Receptor → Spinalcord → Sensory neuron → Motor Neuron → Muscles

Question 28.
Writing is a voluntary action. Are you agree to this ?
Answer:
Writing, talking, moving a chair, clapping at the end of a programme are examples of voluntary actions which are based on deciding what to do next.

Question 29.
One person’s neck is swell. Guess the reason.
Answer:
At the neck region thyroid gland is present by the swelling of this gland his neck is swelled. It is called goiter.

Question 30.
Why do we associate such visible movements with life ?
Answer:
That we think of movement as a response to a change in the environment of the organism.

Question 31.
How do we detect that we are touching a hot object ?
Answer:
All information from our environment is detected by the specialized tips of some nerve cells. These receptors are usually located in our sense organs.

Question 32.
Is there a difference in how sugar and food taste if your nose is blocked ?
Answer:
Yes, there is a difference in taste. When nose is blocked, we can’t find the taste.

Question 33.
Do you come across a similar situation when you have a cold ?
Answer:
Yes, I feel same situation in cold. Nose is blocked in cold, so we can not find the food taste.

Question 34.
Is reflex action the only function of the spinal cord ?
Answer:
Obviously not reflex actions are also controlled by the brain, but without a thinking process.

Question 35.
Plants have neither a nervous system nor muscles. So, how do they respond to stimuli ?
Answer:
Plants have chemical coordination to respond to its surroundings. These are called phytohormones.

Question 36.
Walking in a straight line and riding a bicycle are the activities which are possible due to a part of the brain. Choose the correct location and name of this part from, the given table :

Part of the Brain	Name
A)   Fore brain B)   Mid brain C)   Hind brain D)   Hind brain	Cerebrum Hypothalamus Cerebellum Medulla

Answer:
C) Hind brain – Cerebellum

Question 37.
Sensory nerve of a reflex arc carries information from the receptor cells to the
A) spinal cord
B) brain
C) muscles of the effector organ
D) bones of the receptor organ
Answer:
A) spinal cord

Question 38.
The part in which gustatory receptors are present in our body is
A) inner ear
B) skin
C) tongue
D) inner lining of nose
Answer:
C) tongue

Question 39.
Assertion (A) : The brain allows us to think and take actions based on that thinking.
Reason (R) : The hind brain is the main thinking part of the brain which has regions which receive sensory impulses from various receptors.
A) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
B) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
C) (A) is true, but (R) is false.
D) (A) is false, but (R) is true.
Answer:
C) (A) is true, but (R) is false.

Question 40.
In plants the role of cytokinin is :
A) Promote cell division
B) Wilting of leaves
C) Promote the opening of stomatal pore
D) Help in the growth of stem
Answer:
A & C

Question 41.
Assertion (A) : Plant hormones are chemicals produced inplants which help to coordinate growth, development and response to stimulus and environment.
Reason (R) : Abscisic acid is a plant hormone that promotes cell division.
A) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).
B) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).
C) (A) is true, but (R) is false.
D) (A) is false, but (R) is true.
Answer:
C) (A) is true, but (R) is false.

Question 42.
Observe the three figures given below. Which of the following depicts tropic movements appropriately ?

A) b and c
B) a and c
C) b only
D) c only
Answer:
D) c only

Question 43.
Height of a plant is regulated by
A) DNA which is directly influenced by growth hormone.
B) Genes which regulate the proteins directly.
C) Growth hormones under the influence of the enzymes coded by a gene.
D) Growth hormones directly under the influence a gene.
Answer:
D) Growth hormones directly under the influence a gene.

Question 44.
What are the tropisms shown in the figure ?

Answer:
Root shows geotropic movement and stem shows phototropic movement.

Question 45.
Find the marked one.

Answer:
Mitochondria

Question 46.
Find the marked gland in the human body.

Answer:
Adrenal glands.

Control and Coordination Class 10 Important Questions – 2 Marks

Question 1.
Which are the movements that are related to growth ?
Answer:
Some of these movements are in fact the result of growth, as in plants. A seed germinates and grows, and we can see that the seedling moves over the course of a few days, it pushes soil aside and comes out.

Question 2.
Which are the movements that are related to growth ?
Answer:
Some movements, as in many animals and some plants, are not connected with growth. A cat running, children playing on swings, buffaloes chewing cud – these are not movements caused by growth.

Question 3.
What is a movement ?
Answer:

• Movement as a response to a change in the environment of the organism.
• Movement as an attempt by living organisms to use changes in their environment to their advantage.

Question 4.
Organisms to use changes in their environment to their advantage. Give an example.
Answer:
Organisms to use changes in their environment to their advantage. For example Plants grow out into the sunshine. Children try to get pleasure and fun out of swinging. Buffaloes chew cud to help break up tough food so as to be able to digest it better. When bright light is focussed on our eyes or when we touch a hot object, we detect the change and respond to it with movement in order to protect ourselves.

Question 5.
How is the nervous system made of and what is its function ?
Answer:
Nervous tissue is made up of an organized network of nerve cells or neurons, and is specialized for conducting information via electrical impulses from one part of the body to another.

Question 6.
What are the voluntary actions?
Answer:
Writing, talking, moving a chair, clapping at the end of a programme are examples of voluntary actions which are based on deciding what to do next.

Question 7.
What is the peripheral nervous system ?
Answer:
Peripheral nervous system consisting of cranial nerves arising from the brain and spinal nerves Arising from the spinal cord.

Question 8.
What are the tropic movements ?
Answer:
Plants respond to stimuli slowly by growing in a particular direction. Because this growth is directional, it appears as if the plant is moving, these movements are called tropic movements.

Question 9.
Is the movements in plants are slow? Or quick?
Answer:
The movement of the sensitive platottouch me not) in response to touch is very quick. The movement of sunflowers in response to day or night, on the other hand, is quite slow. Growth-related movement of plants will be even slower.

Question 10.
What are the dramatic changes in the age of puberty ?
Answer:
Many dramatic changes appear in 10-12 years of age. These changes associated with puberty are because of the secretion of testosterone in males and estrogen in females.

Question 11.
Give some examples for reflex actions.
Answer:
Examples of Reflex Action are

• Closing of eyes when a bright light hits our eyes.
• Sudden withdrawing hands or legs when they touch something hot or pricking.
• Coughing or sneezing due to irritants in the nasal passage.
• Batting of eyelids frequently.
• Blinking eyes when insects come in contact.

Question 12.
What are the examples for involuntary movements in our body ?
Answer:
Digestion, heart beating, sneezing, ete. are few examples of involuntary actions. Both involuntary and voluntary actions are controlled by the same parts of the brain. Hindbrain and mid brain control involuntary actions like salivation, vomiting, etc.

Question 13.
What is the pathway in the reflex arc ?
Answer:
The path taken by a nerve impulse during a reflex action is known as the reflex arc. The correct order is
Receptors → Sensory neuron → Spinal cord→ Motor neuron → Muscles.
Reflex arc starts with a stimulus. The stimulus initiates an impulse in a sensory neuron. The sensory neuron carries the impulse to the spinal cord. The spinal cord carries the impulse to appropriate motor neuron. The motor neuron then sends the impulse to either the effector muscle or gland.

Question 14.
Write about the forebrain.
Answer:

• 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 specialized 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.

Question 15.
How do you prove positive and negative geotropism ?
Answer:

• Place a germinated seed horizontally to soil and observe the growth.
• The shoot move towards to light it means away from gravity force. It is negative geotropism.
• But the root moves towards the gravity force. It is positive geotropism.

Question 16.
What are the types of tropism ? Give examples.
Answer:

S.No	Type of tropism	Example
1.	phototropism	shoot
2.	geotropism	root
3.	hydrotropism	root
4.	chemotropism	pollen grains
5.	thigmotropism	tendrils

Question 17.
What are the advantages in nervous coordination ?
Answer:
In the nervous system the responses are much quicker and faster than the chemical coordination. If fast responses to stimuli are to be made, information transfer must happen very quickly. For this, the medium of transmission must be able to move rapidly faster in the nervous system.

Question 18.
What are the limitations in the nervous control system ?
Answer:

• There are limitations to the use of electrical impulses in nervous system.
• Firstly, they will reach only those cells that are connected by nervous tissue, not each and every cell in the animal body.
• Secondly, once an electrical impulse is generated in a cell and transmitted, the cell will take some time to reset its mechanisms before it can generate and transmit a new impulse.
• In other words, cells cannot continually create and transmit electrical impulses.

Question 19.
How the chemical coordination works ?
Answer:

• Instead of generating an electrical impulse, stimulated cells release a chemical compound, in chemical coordination.
• This compound would diffuse all around the original cell. If other cells around have the means to detect this compound using special molecules on their surfaces,
• This will be slower, of course, but it can potentially reach all cells of the body.
• Then they would be able to recognise information, and even transmit it.

Question 20.
Does the plants have a nervous system? If not how they respond ?
Answer:

• Plants does not have any nervous system but they can respond to environment change.
• They have chemical coordination, phytohormones play key role in this process.

Question 21.
If so, why might this be happening ?
Answer:
Gustatory receptors will detect taste in the mouth, while olfactory receptors will detect smell. Both of these receptors work together. So we can’t find the food taste by blocking the nose.

Question 22.
Touching a flame is an urgent and dangerous situation for us, or in fact, for any animal! How would we respond to this ?
Answer:
In hurry and dangerous movements our body responds quickly without thinking about it, or without feeling in control of our reactions. These are called reflexes. By these reflexes we save ourselves from danger, and therefore move our hand.

Question 23.
An important question then is, how long will it take us to think all this ?
Answer:
The answer depends on how we think. If nerve impulses are sent around the way in the reflex arc, then thinking is also likely to involve the creation of such impulses. Thinking is a complex activity, so it is bound to involve a complicated interaction of many nerve impulses from many neurons.

Question 24.
Where should such reflex arc connections be made between the input nerve and the output nerve ?
Answer:
The best place, of course, would be at the point where they first meet each other. Nerves from all over the body meet in a bundle in the spinal cord on their way to the brain. Reflex arcs are formed in this spinal cord itself, although the information input also goes on to reach the brain.

Question 25.
Imagine what would happen if each of these events failed to take place if we were not thinking about it.
Answer:
Reflex actions save us from harmful and dangerous movement without involvement of the brain. If these events fail we face a lot of dangers and sometimes life threats also. So reflexes are a gift to our life.

Question 26.
How does the Nervous Tissue cause action ?
Answer:
Neurons conduct electrical impulses by using the Action Potential. This phenomenon is generated through the flow of positively charged ions across the neuronal membrane.

Question 27.
How do animal muscles move ?
Answer:
When a nerve impulse reaches the muscle, the muscle fiber must move. The simplest notion of movement at the cellular level is that muscle cells will move by changing their shape so that they shorten.

Question 28.
How do muscle cells change their shape ?
Answer:
The answer must lie in the chemistry of cellular components. Muscle cells have special proteins that change both their shape and their arrangement in the cell in response to nervous electrical impulses. When this happens, new arrangements of these proteins give the muscle cells a shorter form.

Question 29.
What would ’hydrotropism’ and ‘chemotropism’ mean ?
Answer:

• Hydro means water, moving or growing of plant parts towards the water is called hydrotropism. Roots show the hydrotropism
• Chemo means chemicals. Plant parts grow towards the chemicals called chemotropism.
  Example of chemotropism is the growth of pollen tubes towards ovules.

Question 30.
Name the part of brain which is responsible for the following actions :
i) Maintaining jposture and balance
ii) Beating of heart
iii) Thinking
iv) Blood pressure
Answer:
i) Maintaining posture and balance : Cerebellum in hind brain
ii) Beating of heart: Medulla in hind brain.
iii) Thinking : Cerebrum in forebrain.
iv) Blood pressure : Medulla in hind brain.

Question 31.
Write the main functions of the following :
a) Sensory neuron
b) Cranium
c) Vertebral column
d) Motor neuron
Answer:
a) Sensory neuron: These often occur in sense organs and receive stimuli through their dendrites. The sensory neurons transmit impulses towards the central nervous system (brain and spinal cord) with the help of their axons.
b) Cranium: The bones of cranium or brain box protect the brain from mechanical injury.
c) Vertebral column : Major function of the vertebral column is protection of the spinal cord and carries the weight of the upper body.
d) Motor neuron : The dendrites of these neurons synapse with axons of interneurons in central nervous system. They transmit impulses from central nervous system towards effectors (muscles or glands). The latter respond to stimuli.

Question 32.
In the given figure, label A represents while label B represents

Answer:
The label A represents trachea while label B represents bronchiole. Tracheal is a windpipe, that carriers air between larynx and bronchi. Bronchioles are the terminal part of bronchi.

Question 33.
Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.
Answer:

The information is transmitted as an electrical impulse. The dendrite passes the electrical signal to the cell body and it further goes to the end point of neuron via axon. Thus, a is cyton or cell body and b is Axon.

Question 34.
Divide the following into groups walking, blinking of eye lids, heart beat, laughing, digestion of food, breathing and reading. Divide them into groups.
Answer:
These can be divided into voluntary actions, involuntary actions and reflex actions.

• Voluntary actions : Walking, laughing, reading.
• Involuntary actions : Digestion of food, heart beat, respiration.
• Reflex actions : Blinking of eye lids.

Question 35.
List two difference between the movement of leaves of a sensitive plant and the movement of a shoot towards light.
Answer:

Movement of leaves of a sensitive plant	Movement of shoot towards light
1. This movement occurs in response to touch or contact stimuli.	1. This movement is independent growth.
2. This is done by plant cells by changing the amount of water in leaves.	2. This movement is known as phototropism. This type of movement is directional and is growth dependent.

Question 36.
What causes tendrils to encircle or coil around the object in contact with it ?
Answer:

• When a tendril touches an object, then the side in contact with object grows slowly than it’s other side.
• This causes the tendril to bend towards the object by growing towards it, wind around object and cling to it.

Question 37.
Explain the function of ethylene.
Answer:

• Ethylene is a gaseous growth inhibiting substance.
• Ethylene causes ripening of the fruits.
• It modifies the growth of the plant by inhibiting stem elongation.
• It accelerates abscission of leaves, flowers and fruits.

Question 38.
How does chemical co-ordination occur in plants ?
Answer:

• Different plant hormones help to co-ordinate growth, development and response to the environment in plants.
• They are synthesised at places away from where they act and simply diffuse to the specific area to produce effect. These plant hormones are called phytohormones.

Question 39.
List two different functions performed by pancreas in our body.
Answer:
The functions performed by pancreas are :

• It secretes enzyme trypsin, which breaks down the protein.
• It also secretes hormone insulin, to regulate the sugar levels in the blood.

Question 40.
Mayank’s father never bothered to check the brand/contents of the salt he had purchased form the market. Mayank noticed that her sister had developed swollen neck. The doctor advised her to eat iodised salt.
Answer the following questions based on above passage.
i) Name the disease from which Mayank’s sister suffered.
ii) Why has the doctor advised her to eat iodised salt ?
iii) How will this incidence influence Mayank’s attitude towards health ?
Answer:
i) Mayank sister is suffering from Goitre/Thyroid related disease.
ii) Iodine present in iodised salt is needed to produce thyroxin hormone.
iii) Mayank would become more careful regarding health and will be conscious of his diet.

Question 41.
Why are some patients of diabetes treated by giving injections of insulin ?
Answer:
Diabetes is a disease in which the level of sugar in the blood is too high.Insulin a hormone secreted by the pancreas helps in regulating the blood sugar levels. This is the reason why diabetic patients are treated by giving injections of insulin.

Question 42.
Name the hormones secreted by thyroid, parathyroid and pancreas.
Answer:

• Thyroid secretes thyroxin.
• Parathyroid secretes calcitonin.
• Pancreas secrete insulin and glucagons.

Question 43.
Read this paragraph and answer the following questions.
How do we know that we have eaten enough? The sensation of feeling full is because of a centre associated with hunger, which is in a separate part of the fore-brain.

1. Which part of the brain controls eating the food ?
Answer: Forebrain.

2. What are the two parts linked in above paragraph?
Answer: Brain and stomach.

Important Questions on Control and Coordination Class 10 – 4 Marks

Question 1.
Draw the neat labelled diagram of the nerve cell.
Answer:

Question 2.
What is the need of control and coordination ?
Answer:

• The movement to be made by the organisms 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 keeping with the general principles of body organization in multicellular organisms, specialized tissues are used to provide these control and coordination activities.

Question 3.
How the information passes in the nerve cells ?
Answer:

• Information, acquired at the end of the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical impulse.
• This impulse travels from the dendrite to the cell body, and then along the axon to its end.
• At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron.
• This is a general scheme of how nervous impulses travel in the body. A similar synapse finally allows delivery of such impulses from neurons to other cells, such as muscles cells or gland.

Question 4.
How the body responds to changes in our surroundings ?
Answer:

• It is no surprise that the thinking tissue in our body consists of dense networks of intricately arranged neurons.
• It sits in the forward end of the skull, and receives signals from all over the body which it thinks about before responding to them.
• Obviously, in order to receive these signals, this thinking part of the brain in the skull must be connected to nerves coming from various parts of the body.
• Similarly, if this part of the brain is to instruct muscles to move, nerves must carry this signal back to different parts of the body.

Question 5.
What is reflex arc ?
Answer:
The nerves that detect heat or any dangerous stimulus were to be connected to the nerves that move muscles in a simpler way, the process of detecting the signal or the input and responding to it by an output action might be completed quickly. Such a connection is commonly called a reflex arc.

Question 6.
What is the role of reflex arcs ? What did they form ?
Answer:

• Reflex arcs have evolved in animals because the thinking process of the brain is not fast enough.
• In fact many animals have very little or none of the complex neuron network needed for thinking.
• So it is quite likely that reflex arcs have evolved as efficient ways of functioning in the absence of true thought processes.
• However, even after complex neuron networks have come into existence, reflex arcs continue to be more efficient for quick responses.

Question 7.
Which part makes a thinking process ?
Answer:

• Thinking involves more complex mechanisms and neural connections.
• These are concentrated in the brain, which is the main coordinating center of the body.
• The brain and spinal cord constitute the central nervous system.
• They receive information from all parts of the body and integrate it.

Question 8.
Draw the neat labelled diagram of the human brain.
Answer:

Question 9.
What are the differences in communication between plants and animals?
Answer:

• The plants also use electrical-chemical means to convey this information from cell to cell, but unlike in animals.
• There is no specialized tissue in plants for the conduction of information.
• In animals, some cells must change shape in order for movement to happen. Instead of the specialized proteins found in animal muscle cells.
• Plant cells change shape by changing the amount of water in them, resulting in swelling or shrinking, and therefore in changing shapes.

Question 10.
What is the role of tendrils in plants ?
Answer:
Some plants like the pea plant climb up other plants or fences by means of tendrils. These tendrils are sensitive to touch. When they come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. This causes the tendril to circle around the object and thus cling to it.

Question 11.
What are the types of tropisms ? Give an example.
Answer:

Tropism	description	example
phototropism	response to light	stem
geotropism	response to gravity	root
chemotropism	response to particular substances	pollen grains
hydrotropism	response to water	root
thigmotropism	response to mechanical stimulation	tendrils

Question 12.
What are limitations to the use of electrical impulses ?
(OR)
What is the need of chemical communication? Do the animals even have electrical communication ?
Answer:

• Firstly, electrical impulses will reach only those cells that are connected by nervous tissue, not each and every cell in the animal body.
• Secondly, once an electrical impulse is generated in a cell and transmitted, the cell will take some time to reset its mechanisms before it can generate and transmit a new impulse.
• In other words, cells cannot continually create and transmit electrical impulses.
• It is thus no wonder that most multicellular organisms use another means of communication between cells, namely, chemical communication.

Question 13.
How is chemical transmission better than electrical transmission ?
Answer:

• Instead of generating an electrical impulse, stimulated cells release a chemical compound, this compound would diffuse all around the original cell.
• If other cells around have the means to detect this compound using special molecules on their surfaces, then they would be able to recognise information, and even transmit it.
• This will be slower, of course, but it can potentially reach all cells of the body, regardless of nervous connections, and it can be done steadily and persistently.

Question 14.
How do the plants bend towards the light ?
Answer:

• When growing plants detect light, a hormone called auxin, synthesized at the shoot tip, helps the cells to grow longer.
• When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot.
• This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light.
• Thus, the plant appears to bend towards light.

Question 15.
“Plant hormones sometimes work together and oppositely” how can you support this statement ?
Answer:

• Plant hormones are gibberellins which, like auxins, help in the growth of the stem. Cytokinins promote cell division, and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds. These are examples of plant hormones that help in promoting growth.
• But plants also need signals to stop growing. Abscisic acid is one example of a hormone which inhibits growth. Its effects include wilting of leaves.

Question 16.
Write about the phytohormones.
Answer:

Hormone	Major Functions
Auxins	Stem elongation, root growth, fruit development.
Cytokinins	Root growth, stimulates germination.
Gibberellins	Seed and Bud Germination, Stem elongation, Fruit development.
Brassinosteroids	Inhibit root growth & leaf abscission.
Abscisic Acid	Inhibits growth, promotes seed dormancy.
Ethylene	Fruit ripening, abscission of leaves.

Question 17.
What changes are caused by the secretion of adrenaline ?
Answer:

• Adrenaline is secreted directly into the blood and carried to different parts of the body. The target organs are the specific tissues on which it acts include the heart.
• As a result, the heart beats faster, resulting in a supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs.
• This diverts the blood to our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles.
• All these responses together enable the animal body to be ready to deal with the situation.

Question 18.
How is the sugar level controlled in our body?
Answer:

• If it is so important that hormones should be secreted in precise quantities, we need a mechanism through which this is done.
• The timing and amount of hormone released are regulated by feedback mechanisms.
• For example, if the sugar levels in blood rise, they are detected by the cells of the pancreas which respond by producing more insulin.
• As the blood sugar level falls, insulin secretion is reduced.

Question 19.
Explain the role of auxins in plant growth.
Answer:

• Auxins are plant hormones that play a crucial role in controlling and coordinating various aspects of plant growth.
• They are primarily responsible for elongation of plant cells, promoting cell division, and influencing the direction of plant growth.
• Auxins are produced in the apical meristems of the shoot tips and young leaves. One of the key functions of auxins is to stimulate cell elongation by increasing the plasticity of cell walls.
• Additionally, auxins help in phototropism by causing the elongation of cells on the shaded side of a plant, leading to bending towards light.

Question 20.
Draw the diagram of the reflex arc neatly labelled.
Answer:

Question 21.
Draw the diagram of the human brain.
Answer:

Question 22.
How is the brain and spinal cord protected ?
Answer:

• A delicate organ like the brain, which is so important for a variety of activities, needs to be carefully protected.
• For this, the body is designed so 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 middle of your back, a hard, bumpy structure is present. This is the vertebral column or backbone which protects the spinal cord.

Question 23.
How do the root and stem show differences in their tropisms ?
Answer:
Plants show tropism in response to other stimuli as well. Shoots respond by bending towards light while roots respond by bending away from the roots of a plant always grow downwards while the shoots usually grow upwards and away from the earth. This upward and downward growth of shoots and roots, respectively, in response to the pull of earth or gravity is, obviously, geotropism.

Question 24.
We all seen salt packets which say ‘iodised salt’ or ‘enriched with iodine’. Why is it important for us to have iodised salt in our diet ?
Answer:

• Iodine is necessary for the thyroid gland to make thyroxine hormone.
• Thyroxin regulates carbohydrate, protein and fat metabolism in the body so as to provide the best balance for growth.
• In case iodine is deficient in our diet, there is a possibility that we might suffer from goiter.
• One of the symptoms in this disease is a swollen neck.

Question 25.
Sometimes we come across people who are either very short (dwarfs) or extremely tall (giants). Have you ever wondered how this happens ?
Answer:

• Growth hormone is one of the hormones secreted by the pituitary. As its name indicates.
• Growth hormone regulates growth and development of the body.
• If there is a deficiency of this hormone in childhood, it leads to dwarfism.
• If the hormone level is more it leads to gigantism

Question 26.
Sometimes the doctor advised to take less sugar in the diet. Why ?
Answer:

• Because they are suffering from diabetes.
• As a treatment, they might be taking injections of insulin.
• This 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.

Question 27.
What is a neurotransmitter ?
Answer:

• Neurotransmitter is a type of chemical messenger that transmits signals across a chemical synapse, from one neuron to another.
• These molecules transmit signals from neurons to muscles, or between different neurons.
• The transmission of signals between two neurons occurs in the synaptic cleft.
• The electrical signals that travel along the axon are briefly converted into chemical signals through neurotransmitters.

Question 28.
What are the divisions of nervous system ?
Answer:
The divisions of nervous system is as follows :

Question 29.
Name the parts (a) to (e) in the following diagram.

What is the term given to the sequence of events occurring in the diagram ?
Answer:

• Receptor
• Sensory neuron
• Spinal cord
• Relay neuron
• Effector

The term given to the sequence of events occuring in the diagram is Reflex Arc.

Question 30.
Look at the given figure and answer the given questions.
a) Identify the parts of a neuron.
b) Where is information acquired ?
c) Through which information travels as an electrical impulse ?

d) Where does this impulse converted into a chemical signal for onward transmission?
Answer:
a. The three main parts of a neuron are

• Cell body
• Axon
• Dendrites.

b. Information is acquired at the end of the dendrites tip of the nerve cell.
c. Sets of chemical reaction that creates an electrical impulse travels from the dendrited to the cell body and then along the axon it’s end.
d. At the end of the axon the chemical impulse sets off the release of some chemicals. These chemicals cross the gap or synapse and start a similar chemical impulses in the dendrite of the next neuron.

Question 31.
Which part of the nervous system controls reflex actions ? Write the sequence of events which occur when we touch a hot object.
Answer:

• Spinal cord of central nervous system controls reflex actions.
• When we touch a hot object receptors of the skin receive the sensation. This sensation of heat is acquired by dendrites of sensory nerve.
• This information travels as electric impulse along the sensory neuron to the relay neuron in the spinal cord, which passes information to the effector, the muscle in arm through motor neuron.
• Dendrites acquire information. In neuron information travels in the form of electric signals called impulse.

Question 32.
Differentiate between reflex and voluntary actions.
Answer:
Differences between Reflex actions voluntary actions :

Reflex actions	Voluntary actions
1. They are controlled by spinal cord.	1. They are controlled by brain.
2. These actions are in voluntary and hence occur without the will of individual.	2. These actions occur with the involvement of individual.
3. These actions involve reflex arc.	3. These actions do not involve reflex arc.

Question 33.
Organs respond to the external stimulus by a fraction of second. How do you feel about such controlling mechanism of human body ?
Answer:

• Organs respond to the external stimulus by a fraction of second. It is due to reflex action.
• These are very important as they save us from painful or dangerous stimuli.
• Reflex actions are very fast, immediate, automatic and involuntary responses of the body.
• Reflexes occur without thinking.
• Brain is not involved in the several reflexes.
  Ex : Withdrawing our hand when we touch the object.

Question 34.
Distinguish between Stimulus – Response.
Answer:
Stimulus – Response :

Stimulus	Response
1. Stimulus is an event or condition that initiates a response.	1. A response is the reaction to a specific function.
2. It is the change in environment.	2. It is reaction to the stimuli.
3. Stimulus varies according to it’s type intensity location and duration. Ex : Car horn.	3. Response may be physical or cellular or it may be behavioural. Ex : Comes to a side.

Question 35.
a) A person is advised by his doctor to take less sugar in his diet. Name the disease from which the person is suffering. Mention the hormone due to imbalance of which he is suffering from this disease.
Which endocrine gland secretes this hormone ?
b) Name the endocrine gland which secretes growth hormone what will be the effect of the following on a person.

• Deficiency of growth hormone.
• Excess secretion of growth hormone.

Answer:
a) The person is suffering from Diabetes mellitus.
The name of the hormone is Insulin which is imbalance and cause for the disease.
The Endocrine gland which secretes Insulin is Pancreas

b) The endocrine gland which secretes growth hormone is Pitutary Gland.

• Deficiency of growth hormone cause dwarfism.
• Excess secretion of growth hormone causes Gigantism.

Question 36.
Differentiate between Dendrites and Axon.
Answer:

Dendrites	Axon
1. The size of dendrites are short and branched.	1. Axons are longer in size, not bra­nched, it is a single like structure.
2. The function of dendrites is to bring message to the cell body.	2. The function of Axon is to transfer the information from the cell body to the dendrites of other neuron.
3. Dendrites are not covered by any membrane.	3. Axon is covered by a sheath called myelin sheath.

Question 37.
Consider that you are passing by a decomposing dead body of a dog at the road side and you immediately cover your nose.
Arrange the events in a logical order by marking them 1 to 5 to trace the events that happens in the nervous system from detection of foul smell (stimulus generation) to covering your nose (response).
i) At the end of the axon, electrical impulse releases chemicals.
ii) Stimulus received by the dendrites of a neuron sets off chemical reaction that creates an electrical impulse.
iii) Electrical impulse transmitted through cell body and axon.
iv) The chemicals cross the synapse and reach the next neuron, similarly, the electrical impulse crosses several neurons.
v) Finally the impulse is delivered from neuron to the gland that helps in recognition of the foul smell and muscle cells that help in covering the nose.
Answer:
The following events occur in nervous system for detecting foul smell of dead and decaying dog
ii) Stimulus received by the dendrites of a neuron sets off chemical reaction that creates an electrical impulse.
iii) Electrical impulse transmitted through cell body and axon.
i) At the end of the axon, electrical impulse releases chemicals.
iv) The chemicals cross the synapse and reach the next neuron, similarly, the electrical impulse crosses several neurons.
v) Finally the impulse is delivered from neuron to the gland that helps in recognition of the foul smell and muscle cells that help in covering the nose.

Question 38.
Which signals will get disrupted in case of a spinal cord injury ?
Answer:

• Reflex actions will be disrupted because spinal cord is one of the components of reflex arc.
• So the quick, responses needed to safeguard the body will not take place. The delayed responses may cause harm to the body.
• For example, delayed response to touching a hot object may cause burn of the body part.
• Impulses from various body parts will not be communicated to brain.
• Messages from brain to body parts will not be communicated.

Question 39.
Observe the diagram and answer the following questions.

i) This diagram belongs to which system of the body ?
Answer: Human nervous system

ii) Name the parts A and B.
Answer:
A. Cerebellum
B. Medulla oblongata

iii) The part ‘C’ is endocrinal gland. This is called master gland. What is the name of this gland ?
Answer: Pituitary gland

iv) Which part in this diagram is useful to solve problems and puzzles ?
Answer: Cerebrum

Question 40.
Ramya ran away shouting loudly after seeing a snake on the way to school. Arrange the events involved in this situation in the correct order and rewrite it.

i) Brain receives the information, analyses and produces the reponse.
ii) Sensory nerves carry the information from sense organs to brain.
iii) Effector muscles exhibit the response.
iv) Sense organs receive the information from the environment.
v) Motor nerves carry the response from the brain to effector muscles.
Answer:
iv) Sense organs receive the information from the environment.
ii) Sensory nerves carry the information from sense organs to brain.
i) Brain receives the information analyse and produces the response.
v) Motor nerves carry the response from the brain to effector muscles.
iii) Effector muscles exhibit the response.

Question 41.
How does the plant detect the touch and how do the leaves move in response ?
Answer:

• Movement happens in a plant at a point different from the point of touch.
• So information that a touch has occurred must be communicated. The plants also use electrical chemical means to convey this information from cell to cell.
• But there is no specialised tissue in plants for the conduction of information.
• Plant cells change shape by changing the amount of water in them resulting in swelling or shrinking.

Question 42.
What are plant hormones? Name the plant hormones responsible for the following
a) Growth of a stem
b) Promotion of cell division
c) Inhibition of growth
d) Elongation of cells
Answer:
Plant hormones – chemical substances which help the plant to co-ordinate growth and development.
a) Growth of a stem : Auxins / Gibberellins
b) Promotion of cell division : Cytokinins
c) Inhibition of growth : Abscisic acid / ABA
d) Elongation of cells : Auxins / Gibberellins

Question 43.
How do auxins promote the growth of a tendril around a support ?
Answer:

• The tendrils are sensitive to touch.
• When a part of tendril comes in contact with a support, the growth hormone auxin diffuses from the tip of the tendril to the side of tendril that is not in contact with the support.
• This causes growth in the part of the tendril away from the support which further causes the tendril to coil around the support. Thus, the tendrils cling to the support.

Question 44.
Design an experiment to demonstrate hydrotropism.
Answer:
Experiment to demonstrate hydrotropism :
Growth movements in response to the stimulus of water (moisture) by roots of the plant is termed as hydrotropic movements, (hydrotropism)

Experiment:

• Take two troughs A and B and fill them with soil. In the trough B place a small clay pot.
• Now plant a small seedling in both troughs.
• Water the soil of trough A uniformly but in trough B put water in clay pot only.
• After few days dig out the seedlings from both the troughs.
• The seedling in trough A which gets uniform water has straight roots while roots of seedling in B trough grows and bend towards the clay pot containing water.

Question 45.
Observe the activity and answer the questions given below :
1. Fill the conical flask with water.
2. Cover the neck of the flask with a wire mesh.
3. Keep two or three freshly germinated bean seeds on the wire mesh.
4. Take a cardboard box which is open from one side.
5. Keep the flask in the box in such a manner that the open side of the box faces light coming from a window.
6. After two-three days you will notice that the shoots bend towards light and roots away from light, leave it undisturbed in this condition for a few days.

Now, answer the questions given below :

a) Have the old shoot and root changed direction ?
Answer: The old parts of the shoot show very less change in direction.

b) Are there differences in the direction of the new growth ?
Answer: Yes, young part of shoot (apex) bends towards light, while root apex bends away from light.
Shoot apex shows positive phototropism and root apex shows negative phototropism.

c) What can you conclude this activity ?
Answer: This activity shows that shoot of plants respond by showing growth movement towards light and roots of the plant respond by showing growth movement away from light.

Question 46.
Which animal or plant hormone is associated with the following ?
i) Increased sugar level in blood
ii) Changes at puberty in boys
iii) Inhibits growth of plants
iv) Rapid development of fruits
v) Dwarfism
vi) Goitre
Answer:
i) Insulin
ii) Testosterone
iii) Abscisic acid
iv) Auxin
v) Growth Hormone
vi) Thyroxine

Question 47.
Why is chemical communication better than electrical impulses as a means of communication between cells in a multi-cellular organism ?
Answer:
In multi-cellular organism chemical communication is better than electrical impulses as a means of communication between cells because :

• Chemical communication is medicated through hormones which can diffuse to different regions of the body.
• Chemical communication does not require any specialized tissue like nervous tissues for signalling to take place.
• Electrical communication is limited to only those regions which are connected by nerves while chemical coordination can take place throughout the body.
• Chemical communication can be done steadily and persistently whereas nervous coordination can be done only at intervals.

Question 48.
A doctor has advised Sameer to reduce sugar intake in his diet and do regular exercise after checking his blood test reports. Which diseases do you think Sameer is suffering from ? Name the hormone responsible for this disease and the organ producing the hormone.
Answer:

• Sameer is suffering from a metabolic disorder Diabetes mellitus, which is characterized by high sugar levels in the blood.
• This condition usually develops from insufficient or no production of the hormone insulin.
• Insulin is secreted by the pancreas and its primary function is the conversion of blood glucose into glycogen for storage.
• Therefore, taking insulin injections will help break down glucose present in the blood, lowering its level.

Question 49.
Name two hormones secreted by pancreas.
Answer:
Pancreas is a heterocrine gland located in the abdomen. It is responsible for the production of many digestive enzymes and hormones. There are two hormones secreted by the pancreas.

• Insulin : It helps in lowering the sugar levels in the blood by converting glucose into glycogen for storage
• Glucagon : It helps in increasing the sugar level in the blood by converting stored glycogen into glucose.

Question 50.
Answer the following :
a) 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 51.
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) Pancreas
c) Adrenal
d) Testes

Question 52.
Read the following table and answer the following questions.

Hormone	Endocrine gland	Functions
1) Growth Hormone	Pituitary	Stimulates the growth in organs.
2) Insulin	Pancreas	Regulates sugar level in blood.
3) Adrenaline	Adrenal	Increase in heart beat, emotions
4) Testosterone	Testes	Development of male sex organs, Beard, moustache

Development of male sex organs, Beard, moustache

1. Which hormone is released at the time of emotions?
Answer: Adrenaline.

2. Name the hormone responsible for secondary sexual characters.
Answer: Testosterone.

3. Which hormone regulates the sugar level in blood ?
Answer: Insulin.

4. Name the hormone which is released by pituitary gland.
Answer: Growth hormone.

Question 53.
Read the paragraph and answer the following questions.

Animals have a nervous system for controlling and coordinating the activities of the body. But plants have neither a nervous system nor muscles. So, how do they respond to stimuli? When we touch the leaves of a chhui-mui (the ‘sensitive’ or ‘touch-me-not’ plant of the Mimosa family), they begin to fold up and droop.

1. Which systems neither plants have ?
Answer: But plants have neither a nervous system nor muscles.

2. What is the use of the nervous system in animals ?
Answer: Animals have a nervous system for controlling and coordinating the activities of the body.

3. What is Stimuli ?
Answer: A thing or event that evokes a specific functional reaction in an organ or tissue.

4. Which plant began to fold when we touched it ?
Answer: Chhui-mui (the ‘sensitive’ or ‘touch-me-not’ plant )

Question 54.
Observe the diagram and answer the following questions.

1. What is the action shown in the diagram 7
Answer: Reflex arc.

2. Which nerves are involved in this process ?
Answer: Both motor and sensory nerves.

3. Which has a key role in this function?
Answer:  Relay neuron in the spinal cord.

4. What is the use of this action ?
Answer: Protects from danger movements.

Question 55.
Observe the diagram and answer the following questions.

1. What is the biggest part of the brain?
Answer: Cerebrum.

2. What is the master gland ?
Answer: Pituitary gland.

3. What is the extension of the brain into the body ?
Answer: Spinal cord.

4. Which part of the brain controls the body balance?
Answer: Cerebellum.

Question 56.
Observe the figure and answer the following questions.

1. What is the aim of this experiment?
Answer: To understand the plant growth towards the direction.

2. Why does the plant grow towards the window ?
Answer: Because of sunlight

3. What are the phenomena you observed in this experiment?
Answer: Phototropisum

4. What is the cause for this phenomena ?
Answer: Phyto hormones known as auxins.

Question 57.
What precautions do you take to avoid diabetes ?
Answer:

• Lose extra weight. Losing weight reduces the risk of diabetes.
• Be more physically active. There are many benefits to regular physical activity.
• Eat healthy plant foods. Plants provide vitamins, minerals and carbohydrates in your diet.
• Eat healthy fats and vegetables.
• Skip fat diets and make healthier choices.

Question 58.
Which habits are best for a healthy brain ?
Answer:
These are five ways to keep your brain healthy :

• Get plenty of sleep. Getting restful sleep is one of the most important things you can do for brain health.
• Protect your head.
• Take care of your mental health.
• Build your social networks.
• Get regular exercise and eat a healthy diet.

Question 59.
How reflex actions help our daily life ?
Answer:
Reflex action is a sudden and involuntary response to stimuli. It helps organisms to quickly adapt to an adverse circumstance that could have the potential to cause bodily harm or even death. Pulling our hands away immediately after touching a hot or cold object is a classic example of a reflex action.

Extra Questions on Control and Coordination Class 10 – 8 Marks

Question 1.
Write about fore brain.
Answer:

• 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 specialized 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, our leg muscles.
• However, certain sensations are distinct from seeing or hearing, for example, how do we know that we have eaten enough? The sensation of feeling full is because of a center associated with hunger, which is in a separate part of the fore-brain.

Question 2.
What are the functions of hindbrain ?
Answer:
1. Many involuntary actions are controlled by the midbrain and hind-brain.
2. For example

• Our mouth waters when we see food we like without our meaning to.
• Our hearts beat without thinking about it. In fact, we cannot control these actions easily by thinking about them even if we wanted to.
• We don’t have to think about or remember to breathe or digest food.
• The simple reflex actions like change in the size of the pupil.
• And the thought out actions such as moving a chair, there is another set of muscle movements over which we do not have any thinking control.
• All these involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla in the hind-brain.
• Think about activities like walking in a straight line, riding a bicycle, picking up a pencil.
• These are possible due to a part of the hind-brain called the cerebellum.
• It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.

Question 3.
How the sensitive plant leaves close when you touch it ?
Answer:

• Leaves of Mimosa pudica are sensitive.
• When touched the stimulus reaches the base of the leaf and the water in the vacuoles of the cells of the leaf loses water to the adjacent cell.
• All the water escapes the leaf which then becomes flaccid. This causes the leaves to close.
• This is due to the passing of impulse which causes the change of turgor pressure.
• Owing to this stimulus, the turgor of the lower half of the pulvinus is lost and the leaf droops down.
• Mimosa plants use their ability to shrink as a defense from herbivores.

Question 4.
Write differences between nastic movements and tropic movements.
Answer:

S.No.		Nastic movements	Tropic movements
1.	Growth	Growth independent movements	Growth dependent movements
2.	Time of action	Immediate	Slow
3.	Response to stimulus	Non-directional	Directional
4.	Reason for action	Change in turgor	Cell division
5.	Alternate name	Nasties	Tropism
6.	Examples	Folding of leaves of touch me-not (mimosa), opening and closing of stomata.	Phototropism, geotropism, hydrotropism, chemotropism.

Question 5.
What are the differences between chemical and nervous coordination ?
Answer:

Feature	Nervous	Hormonal (endocrine)
Made up of	Neurons	Secretory cells
Form of transmission	Electrical impulses	Chemical (hormones)
Transmission pathway	Nerves fibres (axons and dendrons)	Blood plasma
Speed of transmission	Fast	Slow
Duration of effect	Short term	Long term
Response	Localised	Widespread (although there may be a specific target organ)

Question 6.
Write important parts of the brain and their functions.
Answer:

Part of the brain	Peculiarity HSSLive. Guru.	Function
Cerebrum	The largest part of the brain with many fissures and folds in its cortex. Cerebral cortex is seen as grey matter and inner medulla as white matter.	Centre of feeling senses and also the centre of qualities like thought, imagination, intelligence and memory.
Cerebellum	The second largest part, seen as two flaps.	Coordinates muscular activities  and maintains equilibrium of the body.
Medulla oblangata	The rod shaped lower part.	Controls involuntary actions like heart beat and breathing.
Thalamus	The seat of cerebrum.	Acts as relay station of impulses to and fro the cerebrum and also analyses the impulses.
Hypothalamus	Seen just below the thalamus.	Plays a major role in the maintenance of homeostasis.

Question 7.
How does the plant ‘touch-me-not’ plant of the Mimosa family detect the touch, and how do the leaves move in response ?
Answer:

• Information that a touch has occurred must be communicated to leaves.
• The plants also use electrical-chemical means to convey this information from cell to cell.
• Plant cells change shape by changing the amount of water in them, resulting in swelling or shrinking, and therefore in changing shapes.

Question 8.
What do you think the differences between voluntary muscles and involuntary muscles would be ?
Answer:

Voluntary muscles	Involuntary muscles
1. They show striations due to the presence of alternative light and dark bands.	1. Some show striations (cardiac muscles) while others do not (smooth muscles)
2. Movement of these muscles is under the will of the organism.	2. Movement of these muscles is not under the will of the organism.
3. These muscles consist of multi- nucleate cells.	3. These muscles consist of uninucleate cells.
4. The cells are cylindrical in structure.	4. The cells are spindle-shaped or branched.
5. These muscles are found in the hands, legs, tongue etc.	5. These muscles are found in the iris of the eye, in ureters, in the bronchi of the lungs and in the heart.

Question 9.
Write a table of endocrine glands and its secretions.

S.No.	Hormone	Endocrine Gland	Functions
1.	Growth hormone	Pituitary gland	Stimulates growth in all organs
2.	………………….	Thyroid gland	Regulates metabolism for body growth
3.	Insulin	………………….	Regulates blood sugar level
4.	Testosterone	Testes	………………….
5.	………………….	Ovaries	Development of female sex organs, regulates menstrual cycle, etc.
6.	Adrenaline	Adrenal gland	………………….
7.	Releasing hormones	………………….	Stimulates pituitary gland to release hormones

Answer:

S.No.	Hormone	Endocrine gland	Functions
1.	Growth Hormone	Pituitary gland	Stimulates growth in all organs
2.	Thyroxine	Thyroid gland	Regulates metabolism for body growth.
3.	Insulin	Pancreas	RegiSfateslriood sugar level
4.	Testosterone	Testes	Changes during puberty. Develop­ment of male sex organs, behaviour etc.
5.	Oestrogen	Ovaries	Development of female sex organs, regulates menstrual cycle, etc.
6.	Adrenaline	Adrenal	Prepares body to cope with emergency situations.
7.	Releasing hormones	Hypothalamus	Stimulates pituitary gland to release hormones.

Question 10.
Why does the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron take place but not in the reverse direction ? Explain.
Answer:

• The nerve impulses are transmitted from one neuron to the other in the form of electric impulses.
• They enter through the dendrites, move through axon and reach the nerve ending.
• As soon as they reach there, they need to be connected into chemical signals and electric signals are unable to cross the gap called synapse.
• Thus, chemicals called ‘neurotransmiters’ are released from the vesicles that move from nerve endings of one neuron to the dendrites of the next one.
• As the chemicals reach the dendrites to, they again get converted to electrical impulses and move on.

Question 11.
Differentiate between Sensory and Motor nerves.
Answer:
Sensory and Motor nerves :

Sensory nerves	Motor nerves
1. Nerves coming from receptors or sense organs are called sensory nerves.	1. Nerves that carry impulses from brain or spinal cord are called motor nerves.
2. These are also called afferent nerves.	2. These are also called efferent nerves.
3. Sensory nerves carry information from sensory organs like eyes, ears, nose, tongue and skin.	3. The motor nerves carry impulses from brain or spinal cord to effector organs (muscles) and are responsible for the movement of hands and legs.
4. These are incoming nerves.	4. These are outgoing nerves.
5. Ex : Optic nerve, auditory nerves.	5. Ex : Abducens nerve.

Question 12.
You are walking in the traffic suddenly you heard a loud sound. How does co-ordination take place in this situation among respected organs ? Draw a block diagram to explain this situation.
Answer:

Question 13.
i) Define reflex arc and draw a flow chart.
ii) Showing the sequence of events which occur during sneezing.
Answer:
i) The path way taken by nerve impulses in a reflex action is called the reflex arc.

ii) Showing the sequence of events which occur during sneezing.

Question 14.
How does neuron differ from an ordinary cell in the structure ?
Answer:
Differences between Neuron (Nerve cell) and Ordinary cell:

Neuron	Ordinary cell
1. It is the longest cell in our body.	1. Generally cells are round or oval shaped.
2. It belongs to only nervous system.	2. These are the structural units of body.
3. Nerve cell has three parts : a. Cyton b. Axon c. Dendrites	3. Commonly divided as a. Cytoplasm and b. Neucleoplasm.
4. These cells carry impulses to brain and spinal cord.	4. The cells have cell division and replace the death cells.
5. Nerve cells end with nerve terminal at the end of axon and dendrites.	5. These cells do not have end points.
6. Some nerve cells are covered with lipid coat.	6. Generally these are covered with plasma membrane.
7. Nissl granules are special character of nerve cells.	7. These cells do not have Nissl granules.

Question 15.
The human brain is the most complicated organ in animal kingdom – Comment.
Answer:

• Human brain is considered as the most complicated organ in the animal kingdom.
• It has more than 10 billion (1 billion = 100 x 10 lakhs) and 10 to 50 times more number of glial cells.
• Each neuron may receive about 1000 to 10,000 inputs and conduct electrical impulses at a speed of 0.6 to 120 meters / min.
• Brain weights about 2% of body weight but it consumes about 20% of the total oxygen consumed by the body.
• Unlike other tissues, brain is solely dependent on glucose for its energy requirements.
• The greatness of human brain is to analyse a problem and think of a solution.
• The human brain has aesthetic sense to appreciate poetry, music, sculpture, painting and the beauty of objects and nature.
• Another wonderful capacity of human brain is communication through language.
• No other animal can pass on so much of information through sounds as a human being can information through sounds as a human being can.
• The thinking of a human brain can give peace to world or destroy the world.

Question 16.
Compare and contrast nervous and hormonal mechanism for control and co-ordination in animals.
Answer:

Nervous Mechanism	Hormonal Mechanism (Endocrine system)
1. Neurons are the structural and functional unit.	1. Secretory cells are structural and functional unit.
2. Message is transferred in the form of nerve impulse.	2. Message is transferred in the form of chemicals called hormones.
3. Message is transferred through nerves.	3. Hormones are carried throughout the body through blood.
4. Message travels very quickly.	4. Message travels slowly.
5. Effect of message continues for a very short duration.	5. Effect of message continues for a longer time.

Question 17.
Read the following table :
Answer:

Part of the Brain	Functions
a) Olfactory lobes	Sense of smell
b) Cerebrum	Mental abilities, memory, reasoning, perception, emotion and speech, respond to cold, heat, pain and pressure.
c) Diencephalon	Controlling emotions, center for water balance, blood pressure, sensory impulses such as pain, temperature and light, sleep and hunger.
d) Cerebellum	Maintains posture, equilibrium and muscle tope, co­ordinates voluntary movements initiated by cerebrum.

Now, identify the part of the brain which participate in the below situations,
a) Ravi is an intelligent boy. He can remember the things for a long time.
Answer: Cerebrum

b) The drunken man does not walk properly.
Answer: Cerebellum

c) Identifies the food items without seeing which are being prepared in the kitchen.
Answer: Olfactory Lobes

d) Naveen lost his money purse while coming to the school. But he is not crying.
Answer: Diencephalon

e) It is time for lunch.
Answer: Cerebrum

f) I cannot tolerate this type of heat in the summer.
Answer: Cerebrum

g) Catching the ball perfectly.
Answer: Cerebellum

h) There may be a drainage behind the house.
Answer: Olfactory Lobes

Question 18.
Explain tropid movements with suitable examples.
Answer:
Movement of individual parts of plants is possible when they are subjected to external stimuli. This type of response is called tropism or tropic movement.

1. Phototropism : Response of plant to light is called phototropism.
Ex : Bending of stem to light, Sunflower.

2. Geotropism : Response of plant to gravity (gravitational force) is called Geotropism.
Ex : Roots of plants grow positively to gravitational force.

3. Hydrotropism : Response of roots to water availability in the soil.
Ex : Roots grow towards water in the soil (which are close to rocks and walls).

4. Thigmotropism : Response to make contact or touch is called thigmotropism.
Ex : Tendrils of climbers towards support.

5. Chemotropism : Response to chemical is called chemotropism.
Ex : Stigma secretes sugary substance.

Question 19.
A plant which grows near a window bends towards sunlight. Explain why plants possess this type of response?
Answer:

• Auxins are the plant hormones responsible for the growing of the stem towards light.
• The potted plant which is kept near the window in the room, grows towards light.
• Auxins are synthesized at the tip of the stem. They acts on bending of stem response to the sunlight.
• More auxin collects on the light illuminated side of the stem. So cells on that side grow faster.
• On the opposite side cells grow slow to make the stem to bend.
• Bending of the plant towards light is called phototropism.

Question 20.
A creeper entwining it’s tendril to the support is very interesting to watch. How do you express your feeling in this situation ?
Answer:

• A very interesting thing in plants is movement of tendrils.
• All plants show positive response to phototropism.
• But creepers like bittergourd, cucumber the stem is weak and thin. Hence plant cannot grow erect.
• Tendrils play a vital role to make the plant erect. They are thin, thread like growth on the leaves or stems of climbing plants.
• They grow towards support and wind around them.
• This type of response to make contact or touch is called thigmotropism.
• Nature only finds it’s way to grow and survive on the earth.

Question 21.
Give the full form of GH. Name the gland that secretes it. Mention its any two functions. Name the hormone that inhibits the secretion of GH. Name the disorder that is caused due to the failure of secretion of GH.
Answer:

• GH is full form for Growth Hormone.
• Growth hormone is secreted by the pituitary gland.
• It enhances growth in adolescents and children.
• It also contributes to the regulation of body fluids, fat metabolism, sugar and also the functions of the heart.
• It reduces body fat by increasing bone density and muscle mass.
• Somatostatin is a hormone secreted from the hypothalamus that inhibits secretion of Growth hormone.
• Failure of somatostatin secretion results in over secretion of growth hormone. This eventually leads to gigantism in children and acromegaly in adults.
• If there is a deficiency of Growth hormone in childhood, it leads to dwarfism.

Question 22.
Study the table in which the levels of Thyroid Stimulating Hormone (TSH) in women are given and answer the questions that follow on the basis of understanding of the following paragraph and the related studied concepts.

Age Range	Normal (mU/L)	Low (mU/L)
18-29 years 30 – 49 years 50-79 years	0.4 – 2.34 mU/L 0.4 – 4.0 mU/L 0.46 – 4.68 mU/L	< 0.4 mU/L < 0.4 mU/L < 0.46 mU/L

Women are at greater risk for developing abnormal TSH levels during menstruation, while giving birth and after going through menopause.

Around 5% of women in the United States have some kind of thyroid problem compared to 3% of men. Despite claims that high TSH increases your risk for heart disease, a 2013 study found no link between high TSH and heart diseases. But a 2017 study showed that older women are especially at risk for developing thyroid cancer if they have high TSH levels along with thyroid nodules.

Questions.

a) A 35 year old woman has TSH level 6.03 mU/L. What change should she bring in her diet to control this level ?
Answer:
The mentioned woman is suffering from overproduction of TSH or higher TSH level, which is also known as hyperthyroidism. This increased TSH level can be controlled by:

• Lowering the intake of carbohydrates and fat.
• Avoiding the consumption of dairy products.
• Lowering the amount of Sodium in the food.

b) When do woirjen face a greater risk of abnormal TSH level ?
Answer:
In women due to fluctuating levels of estrogen in the body, TSH levels may get disturbed during pregnancy, menstruation, or menopause.

c) State the consequence of low TSH level.
Answer:
Low TSH indicates high function of thyroid gland which may result in hyperthyroidism i.e., increased BMR.

d) Name the mineral that is responsible for synthesis of hormone secreted by thyroid gland.
Answer:
Iodine is mineral responsible for synthesis of thyroxine by thyroid gland.

Conceptual Map