11.
SCHOOL SECTION
The Regulators of Life
259
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SCIENCE & TECHNOLOGY
Q.I
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
(A) Choose the correct alternatives and rewrite the complete sentences :
.................... is necessary to obtain energy from glucose and fatty acid.
(a) Oxygen
(b) Hydrogen
(c) Water
(d) Nitrogen
In certain sensitive plants like Mimosa, movement is in response to the
stimulus of ..................... .
(a) gravity
(b) air
(c) light
(d) touch
The movement of the plant in response to the stimulus of light is called
..................... movement.
(a) gravitropic
(b) hydrotropic
(c) phototropic
(d) chemotropic
When light falls on a part of growing plant, a hormone called .....................
is synthesized at the tip of the shoot.
(a) auxin
(b) abscissic acid
(c) gibberellins
(d) cytokinins
The movement of the root system towards the stimulus of gravity is called
..................... movement.
(a) gravitropic
(b) hydrotropic
(c) phototropic
(d) chemotropic
The movement of the root system towards the stimulus of water is called
..................... movement.
(a) gravitropic
(b) hydrotropic
(c) phototropic
(d) chemotropic
..................... hormones help in the growth of the stem.
(a) Auxins
(b) Abscissic acid
(c) Gibberellins
(d) Cytokinins
..................... hormones promote cell division.
(a) Auxins
(b) Abscissic acid
(c) Gibberellins
(d) Cytokinins
..................... is a plant hormone which inhibits growth wilting of leaves.
(a) Auxin
(b) Abscissic acid
(c) Gibberellins
(d) Cytokinins
The ..................... is the main thinking part of the brain.
(a) cerebrum
(b) cerebellum
(c) medulla oblongata
(d) spinal cord
The brain can stay alive for ..................... without oxygen.
(a) 4-6 hours
(b) 5-6 hours
(c) 24 hours
(d) 4-6 minutes
Answers :
1. Oxygen
3. phototropic
5. gravitropic
7. Gibberellins
9. Abscissic acid
11. 4-6 minutes.
Q.I
*1.
*2.
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2.
4.
6.
8.
10.
touch
auxin
hydrotropic
Cytokinins
forebrain or cerebrum
(B) Fill in the blanks :
..................... do not possess a nervous system.
Response to the stimulus of touch is called ..................... whereas response
to the stimulus of chemicals is called as ..................... .
SCHOOL SECTION
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*3.
*4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
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15.
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17.
18.
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20.
21.
22.
23.
24.
25.
26.
SCIENCE & TECHNOLOGY
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Brain is the main ..................... centre of the body.
The loss of water from the plants is known as ..................... .
..................... refers to the systematic regulation of various activities.
..................... means the orderly execution of the activities.
Transpiration takes place in the leaves through the ..................... .
The food is mixed with the ..................... in the saliva secreted by the
salivary glands.
The movement or growth of any part of a plant in response to an external
stimulus is called ..................... .
The plants use ..................... means to transfer information from one cell
to another.
The nerves are composed of neurons and ..................... .
The neurons are specialized cells capable of transmitting ..................... .
..................... neurons conduct impulses from the sense organs to the
brain and spinal cord.
..................... neurons conduct impulses from the brain and spinal cord to
the effector organs.
..................... neurons perform the integrative functions of the nervous
system.
..................... keeps the CNS well nourished and also protects it by absorbing
mechanical shocks.
The chemical control is brought about by chemical substances called
..................... .
The hormones are secreted by the ..................... glands.
Endocrine glands are also known as the ..................... glands.
Hormones are also referred to as ..................... .
Insect ..................... is under hormonal control.
In frogs ..................... secretion stimulates the metamorphosis from tadpole
to adult frog.
In the ....................., hormones induce colour changes and are influential
in regulating development.
The left hemisphere of the brain has ..................... more neurons than
the right hemisphere.
..................... of blood flows through the brain every minute.
In certain coelenterates like ....................., the nervous system is at a
very primitive stage of developments.
Answers :
1. Plants
3. thinking
5. Control
7. stomatal openings
9. tropism or tropic movement
11. neuroglia
13. Sensory
15. Association
17. hormones
19. ductless
21. metamorphosis
23. arthropods
25. 750-1000 ml
SCHOOL SECTION
2.
4.
6.
8.
10.
12.
14.
16.
18.
20.
22.
24.
26.
seismonastic movement, chemotropism
transpiration
Co-ordination
enzymes
electrochemical
electrochemical impulses
Motor
Cerebrospinal fluid (CSF)
endocrine
chemical messengers
thyroid
186 millions
hydra.
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Q.I
1.
(i)
(ii)
(iii)
(iv)
(v)
Ans.
2.
(i)
(ii)
(iii)
(iv)
Ans.
3.
(i)
(ii)
(iii)
(iv)
Ans.
4.
(i)
(ii)
(iii)
(iv)
Ans.
(C) Match the following :
Column I
Seismonastic movement
(a)
Phototropic movement
(b)
Gravitropic movement
(c)
Hydrotropic movement
(d)
Chemotropic movement
(e)
(i - d), (ii - c), (iii - a), (iv - e), (v - b).
Column I
Folding of leaflets in Mimosa
pudica
Growth of pollen tube towards
the ovules
Bending of plant towards light
Movement of roots towards water
(i - b), (ii - a), (iii - d), (iv - c).
Column I
Gibberellins
Cytokinins
Abscissic acid
Auxins
(i - c), (ii - a), (iii - d), (iv - b).
Column I
Lotus plant
Tube rose plant
Tentacles of Drosera
Fruit of Balsam plant
(i - b), (ii - d), (iii - a), (iv - c).
Column II
Chemotropism
(b)
Seismonastic
(c)
(d)
Hydrotropism
Phototropism
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
Column I
CNS
(a)
(2)
PNS
(b)
(3)
(4)
ANS
Endocrine system
spinal
(i - c), (ii - d), (iii - a), (iv - b).
(c)
(d)
6.
(i)
(ii)
(iii)
(iv)
Ans.
262
Column I
Taste buds at the tip of the tongue
Olfactory receptors
Taste buds at the back of the
tongue
Taste buds at the sides of the
tongue
(i - d), (ii - c), (iii - b), (iv - a).
gravity
chemicals
light
touch
water
(a)
5.
(1)
Ans.
Column II
Stimulus of
Stimulus of
Stimulus of
Stimulus of
Stimulus of
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Column II
Promoting cell division in fruits and
seeds
Tip of shoot to grow longer
Promoting growth of stem
Wilting of leaves
Column II
Curl inwards at the touch of an
insect, trapping it
Open in morning
Bursts open scattering the seeds.
Open at night
Column II
Comprises of nerves present in
involuntary organs like heart,
stomach, lungs, etc.
Comprises of the ductless glands
secreting hormones
Comprises of brain and spinal cord
Comprises of cranial nerves and
nerves
(a)
(b)
(c)
Column II
Detect salty and sour tastes
Detect bitter tastes
Sense of smell
(d)
Detect sweet tastes
SCHOOL SECTION
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SCIENCE & TECHNOLOGY
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7.
(i)
(ii)
(iii)
Column I
Medulla oblongata
Spinal cord
Cerebellum
(a)
(b)
(c)
(iv)
Cerebrum
(d)
Ans.
Q.I
1.
Ans.
2.
Ans.
3.
Ans.
4.
Ans.
5.
Ans.
6.
Ans.
7.
Ans.
8.
Ans.
9.
Ans.
10.
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11.
Ans.
12.
Ans.
13.
Ans.
14.
Ans.
15.
Ans.
Column II
Reflex arc
Main thinking part of brain
Involuntary activities like
breathing, blood flow, etc.
Voluntary movements and
maintaining balance of the body
(i - c), (ii - a), (iii - d), (iv - b).
(D) State whether the following statements are true or false. If false
write the corrected statement :
The loss of water from the plants is known as translocation.
False. The loss of water from the plants is known as transpiration.
Transpiration takes place in the leaves through stomatal openings.
True.
There is growth involved in the seismonastic movement exhibited by plants.
False. There is no growth involved in the seismonastic movement exhibited
by plants.
Unlike animals, plants do not have a nervous system or muscular system.
True.
When light falls on growing plants, the hormone auxin is synthesized at
the tip of the root.
False. When light falls on growing plants, the hormone auxin is synthesized
at the tip of the shoot.
Plants possess specialized tissue for conduction of information of touch to
bring about movement.
False. Plants use electrochemical means to transfer the information.
The central nervous system comprises of all the nerves.
False. The CNS comprises of brain and the spinal cord.
The neuroglia are supportive cells which assist the neurons in their
function.
True.
All the information from our environment is picked up by axons of a neuron.
False. All the information from our environment is picked up by the
specialized tips of dendrites of a neuron.
Muscle cells possess special kinds of proteins which help them change
their shape.
True.
Sensory neurons conduct impulses from sense organs to the brain and
spinal cord.
True.
Motor neurons conduct impulses from effector organs like muscles and
glands to brain and spinal cord.
False. Motor neurons conduct impulses from brain and spinal cord to effector
organs.
Human brain, on an average, weighs 1300 - 1400 gram.
True.
Cranial nerves arise from spinal cord.
False. Cranial nerves arise from the brain whereas spinal nerves arise
from the spinal cord.
The forebrain or the cerebrum is the main thinking part of the brain.
True.
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16.
Ans.
17.
Ans.
18.
Ans.
19.
Ans.
Q.I
1.
Ans.
2.
Ans.
3.
Ans.
4.
Ans.
5.
Ans.
6.
Ans.
Q.I
1.
Ans.
2.
Ans.
3.
Ans.
4.
Ans.
5.
Ans.
6.
Ans.
7.
Ans.
8.
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9.
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Nerve impulses are slower and long lasting whereas hormonal action is
rapid and of short duration.
False. Nerve impulses are rapid and of short duration and hormonal action
is much slower and long lasting.
The medulla oblongata is a component of the mid brain.
False. The medulla oblongata is a component of the hind brain.
The medulla oblongata controls vital involuntary activities like blood flow,
breathing, sneezing, etc.
True.
Affarent nerves carry impulses from the brain to the sensory organs.
False. Affarent nerves carry impulses from the sensory organs to the nerves.
(E) Find the odd man out :
Digestion, Transpiration, Circulation, Excretion.
Transpiration. It is a process which takes place in plants whereas the
rest are processes occurring in animals.
Seismonastic, Phototropic, Chemotropic, Hydrotropic
Seismonastic. It is a growth independent movement whereas rest are
growth dependent movements.
Gibberellins, Auxins, Cytokinins, Thyroxine.
Thyroxine. It is a growth hormone in animals whereas the rest are growth
hormones in plants.
Spinal cord, Cerebrum, Cerebellum, Medulla oblongata.
Spinal cord. It is not a part of the brain, whereas the rest are the three
regions of the brain.
Dendrite, Cell body, Axon, Synapse.
Synapse. It is a microscopic gap between two neurons whereas the rest
are main parts of the neuron.
Auxin, Gibberellins, Insulin, Abscissic acid.
Insulin. It is a hormone in animals whereas the rest are hormones in plants.
(F) Write the correlated terms :
Loss of water : Transpiration :: Ascent of sap : ....................... .
Translocation.
Movement of shoot system : Phototropic :: Movement of root system :
....................... .
Gravitropic and hydrotropic.
Brain : Cranium :: Spinal cord : ....................... .
Vertebral column.
Cavities of the brain : Ventricles :: Cavity of the spinal cord : ....................... .
Central canal.
Central nervous system : Brain and spinal cord :: Peripheral nervous system
: ....................... .
Nerves.
Involuntary activities : Medulla oblongata :: Balance of the body :
....................... .
Cerebellum.
Tip of the tongue : Sweet taste :: Back of the tongue : ....................... .
Bitter taste.
Bending of stem towards light : Phototropism :: Growth of pollen tube towards
ovules : ....................... .
Chemotropism.
Growth of the stem : Gibberellins :: Wilting of leaves : ....................... .
Abscissic acid.
SCHOOL SECTION
MT
Q.II
*1.
Ans.
*2.
Ans.
*3.
Ans.
*4.
Ans.
*5.
Ans.
6.
Ans.
7.
Ans.
8.
Ans.
9.
Ans.
10.
Ans.
11.
Ans.
Q.II
1.
Ans.
2.
Ans.
3.
Ans.
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(A) Name the following :
Growth of plant in response to external factors.
Tropism.
Maintenance of steady state by different systems in an organism.
Homoeostasis.
Cells those assist the neurons in their function.
Neuroglia.
The small gap between the consecutive neurons.
Synapse.
Part of the brain that co ordinates the voluntary movements.
Cerebellum.
The bony structure protecting the brain.
Cranium (skull).
The bony structure protecting the spinal cord.
Vertebral column (Backbone).
Protective membranes in the space between the soft CNS and bone.
Meninges.
Cavities present on the different parts of the brain.
Ventricles.
Long cavity present in the spinal cord.
Central canal.
Fluid present in the cavities of brain, spinal cord and space between
meninges.
Cerebrospinal fluid.
(B) Define the following :
Homoeostasis.
The maintenance of the steady state by different systems of an organism
for its optimal functioning because of a perfect co-ordination is called
homoeostasis.
Tropism OR Tropic movements.
The movement or growth of any part of a plant in response to an external
stimulus is called tropism or tropic movements.
Reflex action.
Any sudden action in response to some happening in the environment,
without thinking about it or without feeling in control of our reactions is
called reflex action.
Q.III (A) Give scientific reasons :
*1. Roots of plants go away from light.
Ans. 1. The roots of plants respond to the stimulus of gravity and water.
2. These responses are called gravitropic and hydrotropic movements
respectively.
3. Plants absorb water in which minerals are dissolved, from the soil with
the help of their roots.
4. Therefore, roots of plants go away from light.
*2. Hormones secreted by the endocrine glands are present everywhere in
the body.
Ans. 1. The chemical control is brought about by chemical substances called hormones.
2. These hormones are secreted by endocrine glands or ductless glands.
3. These glands do not have any duct to store or transport their secretions.
4. Thus, on production these hormones are directly released into the
blood stream.
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Ans.
4.
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5.
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5. Due to this, the hormones reach everywhere in the body, though the
gland secreting them is located in a particular place.
6. Therefore, hormones secreted by the endocrine glands are present
everywhere in the body.
Insulin plays an important role in controlling the sugar level of blood.
1. Insulin is a hormone which controls the sugar level of blood.
2. It is very important that insulin should be secreted according to the
amount of sugar in the blood.
3. The required quantity of insulin released and the time of released are
regulated by feedback mechanisms.
4. When the sugar level of blood rises, it it detected by the cells of the
pancreas which respond to the situation by producing more insulin so
that the sugar level comes back to normal.
5. On the other hand, as the sugar level of the blood falls, the secretion of
insulin is reduced.
6. Therefore, insulin plays an important role in controlling the sugar level
of blood.
Tendril entwines itself around the object and clings to it.
1. Tendrils are sensitive to touch.
2. When they come in contact with any object, the portion of the tendril which
is in contact, becomes sluggish whereas growth is faster at the other portion.
3. This causes the tendril to entwine itself around the object and thus
cling to it.
Reflex arcs are evolved in animals.
1. In animals, the thinking process of the brain is a bit slow.
2. In many animals, specially lower animals the complex neuron network
needed for thinking is not there or is not well developed.
3. Hence reflex arcs have been evolved as efficient ways of functioning in
the absence of the true thought process.
4. However, in spite of the presence of complex neuron networks, reflex
arcs continue to be more efficient for quick responses.
Q.III (B) Answer the following questions in short :
1. State the characteristic features of living organisms. Which
characteristic feature is less conspicuous in plants ?
Ans. 1. Living organisms are made up of cells.
2. They need nutrition.
3. They grow and develop up to certain limits.
4. They receive stimuli from the environment and respond to the same.
5. They reproduce.
6. They show structural and functional organization.
7. They show ability to adapt to changes in their environment.
Out of these features, showing the ability to adapt to the changes in their
environment is less conspicuous in plants.
2. How do we taste food ?
Ans. 1. There are distinct regions on the tongue where main tastes are detected
or recognized.
2. Taste buds at the tip of the tongue detect sweet tastes, those at the
back detect bitter tastes and those at the side of the tongue detect
salty and sour tastes.
3. The taste buds on the tongue transmit the different taste information
as a message to the brain.
4. Brain processes the information and tells us what food is actually in
our mouth.
266
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3.
Ans.
4.
Ans.
*5.
Ans.
6.
Ans.
7.
Ans.
8.
Ans.
9.
Ans.
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How do we smell ?
1. Smells enter the back of the nose when you inhale. They also rise up
from the back of the mouth as we eat, which is why smell is such an
important part of tasting and enjoying food.
2. This is the reason why food tastes odd when we have a cold as the
nasal organs become inflamed and the sense of smell is temporarily
smothered.
How does our memory work ?
1. Sensory memory is brief, it tells us what is happening around us.
2. Short term memory lasts only for 30 seconds. Eg. We remember a
phone number and dial it and then it vanishes.
3. Long term memory is for the things that we have carefully learned and
memorized.
Classify the following as voluntary and involuntary movements.
1. Coughing
2. Food getting digested
3. Moving a table
4. Kicking a ball
5. Beating of heart
6. Release of hormones into blood
7. Flying a kite.
1. Coughing
– Involuntary
2. Food getting digested
– Involuntary
3. Moving a table
– Voluntary
4. Kicking a ball
– Voluntary
5. Beating of heart
– Involuntary
6. Release of hormones into blood – Involuntary
7. Flying a kite
– Voluntary.
Give examples of growth independent movements in plants.
1. Closing of leaflets of mimosa plant when touched.
2. Opening of lotus in the morning and tuberose at night.
3. Insectivorous plants like drosera curl inwards at the touch of an insect
and trap the insect.
4. The explosive fruit of balsam plant bursts open at an appropriate time
thus scattering the seeds.
How does the Venus flytrap traps insects ?
1. The Venus flytrap has a trap which looks an smells like a flower to insects.
2. When insects land on it, they touch a trigger hair which slams the trap
shut and they are then digested by the plant.
How are neurons classified ? State their functions.
1. Neurons are of three types i.e. sensory neuron, motor neuron and
association neuron.
2. Sensory neurons conduct impulses from the sense organs to the brain
and spinal cord.
3. Motor neurons conduct impulses from the brain and spinal cord to the
effector organs like muscles and glands.
4. Association neurons perform integrative functions of the nervous system.
How are nerves categorized based on their functions ?
1. On the basis of their functions, the nerves are categorized as afferent
nerves and efferent nerves.
2. Afferent nerves carry impulses from the sensory organs to the brain.
3. Efferent nerves carry impulses from the brain to the sensory organs.
Q.III (C) Write short notes for the following :
*1. Reflex action.
Ans. 1. Any sudden change in response to some happening in the environment,
is called as reflex action.
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*2.
Ans.
Q.IV
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2. We react to such a situation without thinking about it or without feeling
in control of our reactions.
3. Example : When we touch a vessel containing very hot tea, immediately
the hand is withdrawn.
4. In this case, the nerves that detect pain are connected to the nerves
that bring about the action of the muscle, hence the action is completed
quickly.
5. Nerves from all over the body meeting in a bundle in such a connection
is called as the spinal cord.
6. Hence reflex arcs are formed in the spinal cord, although the messages
reach the brain.
Co-ordination in plants.
1. Plants do not have a nervous system or muscular system.
2. The movements exhibited by plants are mainly in response to the
stimulus.
3. In certain sensitive plants like Mimosa, movement is in response to
the stimulus of touch. This movement is known as seismonastic
movement. There is no growth involved in this movement.
4. On the other hand, the movement of a seedling is because of growth. If
growth is prevented, it does not exhibit any movement.
5. Thus, we conclude that plants exhibit two types of movement, one which
is growth dependent movement and the other which is growth
independent movement.
(A) Distinguish between :
Voluntary movements and Involuntary movements.
Voluntary movements
Involuntary movements
1. Movements which are under our 1. Movements which are not under
control are called voluntary
our control are called involuntary
movements.
movements.
2. Voluntary movements require 2. Involuntary movements do not
thinking.
require thinking.
3. Voluntary
movements
are 3. Involuntary movements are
controlled by cerebellum.
controlled by midbrain and
hindbrain.
4. Eg. Moving a table, kicking a ball, 4. Eg. Blood flow, breathing,
walking, clapping hands etc.
sneezing etc.
2.
Ans.
Growth dependent movements and Growth independent movements.
Growth dependent movements
Growth independent movements
1. Growth dependent movements 1. Growth independent movements
result in growth of the plants.
do not result in growth of the
plants.
2. Growth dependent movements 2. Growth independent movements
are also called as tropic
are also known as nastic
movements.
movements.
3. Growth dependent movements 3. Growth independent movements
are in response to the stimulus
are in response to the stimulus
of light, water, gravity etc.
of touch.
4. Eg. Bending of stem towards 4. Eg. Closing of leaflets in mimosa
light, movement of roots towards
plant, shutting of Venus flytrap.
gravity and water.
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3.
Ans.
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Central nervous system and Peripheral nervous system.
Central nervous system
1. Central nervous
composed of brain
cord.
2. Central nervous
located in the centre
4.
Ans.
Peripheral nervous system
system is 1. Peripheral nervous system is
and spinal
composed of all the nerves.
system is 2. Peripheral nerves are spread
of the body.
throughout the body.
Cerebrum and Cerebellum.
Cerebrum
Cerebellum
1. Cerebrum is the part of forebrain. 1. Cerebellum is the part of
hindbrain.
2. Cerebrum is responsible for 2. Cerebellum is responsible for
thinking
and
interpreting
coordinating the voluntary
sensory information.
movements and also maintaining
the balance of the body.
Q.IV
1.
Ans.
(B) Draw a neat and labelled diagram of the following :
Human brain showing different areas and their responsibilities.
Movement area
Touch area
Thought area
Hearing area
Vision area
Speed
2.
Ans.
V.S. of human brain.
Corpus
callosum
Cerebrum
Pineal body
Pituitary gland
Pons varolii
Medulla oblongata
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Arbor vitae
Cerebellum
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3.
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Neuron.
Dendrites
Cyton (cell body)
Nucleus
Axon
4.
Ans.
Neuromuscular junction.
Axon Neuromuscular
junction
Muscle fiber
Mitochondrion
Capillary
5.
Ans.
Chemotropism (Growth of Pollen tube towards the ovules).
Pollen grain (germinating)
Pollen tube
Zygote formation
Ovum
(a)
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Ans.
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Reflex arc.
Spinal chord (CNS)
Message
to brain
Sensory neuron
Receptors-heat pain
Receptors in skin
Motor
neuron
Relay neuron
Effector-muscle in arm
Q.V
1.
Ans.
2.
Ans.
Answer the following in detail :
What is co ordination ? Explain its importance.
1. Co ordination means orderly execution of the activities, so that an
organism shows proper growth and development.
2. For example, man sees food, hand picks it up and puts it into the
mouth. The morsel of food is chewed in the mouth with the help of
teeth assisted by the tongue. The food is mixed with the enzymes in
the saliva secreted by salivary glands.
3. For further biochemical reactions, the food is sent to stomach and the
complex food materials are broken down into simple forms such as
glucose, amino acids and fatty acids.
4. The simple digested food is absorbed into blood through intestines and
undigested food is excreted.
5. Thus digestion, absorption, circulation, excretion are interdependent.
6. Oxygen is necessary to obtain energy from glucose and fatty acid.
Oxygen is supplied by the process of respiration.
7. Thus, various organ systems function in a synchronized manner. Coordination is necessary between organs and organ systems that bring
about all the inter-related life processes.
8. Any disturbance at any stage due to lack of co-ordination can leave the
desired process incomplete.
9. Thus for successful completion of desired process, there has to be perfect
co ordination between different systems and / or organs involved at
every step.
What is homoeostasis ? How is it maintained in an individual’s body ?
1. The maintenance of the steady state by different systems of an organism
for its optimal functioning because of a perfect co ordination is called
homoeostasis.
2. Control and co ordination provide stability and maintenance of the steady
state i.e. creation of a relatively constant environmental condition within
any organism.
3. In an individual’s body perfect co ordination between internal activities
of the body caused due to water or enzyme level and temperature etc.
and similar such external environmental stimuli must be there to
achieve homoeostasis (e.g. In summer, with excessive sweating we
feel more thirsty.)
4. In animals, nervous system along with hormones bring about co
ordination.
5. In plants, due to lack of nervous system only hormones bring about
chemical co ordination.
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What is tropic movement ? Describe the different types of tropic
movements.
The movement or growth of any part of a plant in response to an external
stimulus is called tropism or tropic movement.
Tropic movements are of three types :
1. Phototropic movement (Phototropism) : The movement of a plant in
response to the stimulus of light is called phototropism. E.g. the shoot
system of any plant responds towards the stimulus of light i.e. it grows
in the direction of source of light.
2. Gravitropic movement (Gravitropism) : The root system of the plants
responds to the stimulus of gravity. This movement is called as
gravitropic movement.
*3. Hydrotropic movement (Hydrotropism) : The root system of the plants
responds to the stimulus of water. This movement is called hydrotropic
movement.
4. Chemotropic movement (Chemotropism) : It is the movement of a
plant part in response to certain chemicals. E.g. the growth of pollen
tube towards the ovules.
Which are the different parts of the human nervous system?
The human nervous system can be divided into :
1. The Central Nervous System (CNS) : It comprises of the brain and
spinal cord and regulates all activities of the body.
2. The Peripheral Nervous System (PNS) : It includes all the nerves. The
nerves form a network and spread throughout the body. They are
instrumental in connecting all parts of the body to the central nervous
system.
3. The Autonomic Nervous Sytem (ANS) : If comprises of all the nerves
present in the involuntary organs like heart, stomach, lungs etc.
4. On the basis of their function, the nerves are categorized as afferent
and efferent nerves.
5. The nerves are composed of neurons and neuroglia. The neurons are
specialized cells capable of creating and transmitting electrochemical
impulses. The neuroglia are supportive cells which assist the neurons
in their function.
Describe the Central Nervous System in human beings.
1. The central Nervous system is a delicate structure composed of the
brain and spinal cord.
2. The brain is protected by a bony structure called cranium or skull and
the spinal cord is protected by the vertebral column or the back bone.
3. In between the soft CNS and the bone are present protective membranes
called the meninges.
4. There are cavities present on the different parts of brain known as
ventricles, while the long cavity of the spinal cord is called central
canal.
5. The ventricles, central canal and the space between the meninges are
filled with cerebrospinal fluid (CSF).
6. The CSF keeps the CNS well nourished and also protects it from
absorbing mechanical shocks.
7. The brain is a complex organ divided into three regions : the forebrain,
midbrain and hindbrain.
8. The forebrain or cerebrum is the main thinking part of the brain. It has
regions which receive the sensory impulses from various receptors.
The areas for smell, hearing, vision etc. are separate.
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9. Even there are different areas where the sensory information is received
and interpreted and put together with the information received from
other receptors as well as the information that is already stored in the
brain. Such centres are known as association centres.
10. Involuntary activities like blood flow, breathing, sneezing etc. are
controlled by Medulla oblongata, a component of the hind brain.
11. Another component of the hind brain is cerebellum. It is responsible
for co-ordinating the voluntary movements and also maintaining the
balance of our body. Eg. riding a bicycle, picking up an object from the
floor, running along a straight line etc.
12. Spinal cord is an important part of the CNS which extends through the
vertebral column. It controls the reflex actions.
13. Each side of our brain controls the opposite side of the body. Usually
the left side of the brain controls speaking, writing and logical thought.
The right side of the brain controls artistic abilities.
Describe chemical co ordination in animals.
1. The chemical control is brought about by chemical substances called
hormones.
2. These hormones are secreted by endocrine glands also known as the
ductless glands.
3. On production these hormones are directly released into the blood
stream, due to this the hormones reach every where in the body though
the gland secreting them is located in a particular place.
4. The endocrine system shares its responsibility of control and co
ordination with the nervous system. Both systems work in co-operation
to integrate and control various body activities.
5. The significant difference between the two systems is that the nerve
impulses are rapid and are usually of short duration while the hormonal
action is much slower and longlasting.
6. Eg. Suppose some animal like rabbit is caught in a scary situation, its
body has to be prepared either to fight with the situation or to run away
from there. Both are extremely complicated activities that will utilize a
great deal of energy in controlled ways.
7. If the body of the rabbit has to trust only the electrical impulses through
nerve cells, then the tissues instructed to get prepared for the activity
would be limited. On the other hand, if chemical signals were to be
sent, it would reach each and every cell of the body and render a wide
range of changes that are needed.
8. In chemical co-ordination, the hormones are secreted according to the
requirement. The required quantity of hormone released and the time
of release is regulated by feedback mechanisms.
Example : When the sugar level of blood rises, it is detected by the
cells of the pancreas which respond to the situation by producing more
insulin. As the sugar level of the blood falls, the secretion of insulin is
reduced.
Describe the conduction of nerve impulse.
1. Nerves are composed of neurons and neuroglia. The neurons are
specialized cells capable of creating and transmitting electrochemical
impulses.
2. All the information from our environment is picked up by the specialized
tips of dendrites of a neuron.
3. This sets off a chemical reaction producing an electrical impulse which
travels from dendrite to cell body, from there through the axon (nerve
fibre) to its end.
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4. At the end of the first axon, the electrical impulse induces release of
some chemicals.
5. These chemicals produced go across the small gap (synapse) of 2 20nm between the neurons and start a similar electrical impulse in
the dendrite of the next neuron.
6. The impulses travel in body in the above manner from the neurons and
are delivered to the muscle cell or glands.
7. When an action or movement has to be brought about, the muscle
tissue does the final job. Muscle cells possess special kinds of proteins
which are capable of bringing about change in their shape and make
the cell capable to respond to the nervous electrical impulses.
Describe the movements in plants which are growth independent.
1. Certain movements of plants do not result in their growth and are
termed as growth independent movements.
2. Hormones bring about various movements in plants in response to the
changes occuring in their surroundings.
3. These movements also happen at a place different from the place of
touch. This means that the information that a touch has occured has
been communicated. Eg. Closing of leaflets of Mimosa on touch.
4. Plants use electrochemical means to transfer information from cell to
another as there is no specialized tissue for the conduction of
information.
5. Then the movement is brought about as the plant cells change their
shapes by altering the amount of water in them. By this the cells
either swell or shrink and thus change their shape.
6. Some other movements seen in plants which are growth independent
are - lotus opens in the morning and the tube rose opens at night, the
tentacles on the leaves of the insectivorous plants like Drosera curl
inwards at the touch of an insect and trap the insect, the explosive
fruit of balsam plant bursts open at appropriate time thus scattering
the seeds.
7. The Venus flytrap which looks and smells like a flower to insects.
When they land on it they touch a trigger hair which slams the trap
shut and they digested by the plant.
Describe the growth dependent movements in plants.
1. The movement or growth of any part of a plant in response to an external
stimulus is called tropism or tropic movements.
2. The shoot system of any plant responds towards the stimulus of light
i.e., it grows in the direction of source of light. When a potted plant is
kept near the window in a room, the stem bends slightly towards the
window. This movement exhibited by the plant is called phototropic
movement.
3. When light falls on a part of growing plant, a hormone called auxin
which is synthesized at the tip of the shoot helps the cells to grow
longer. As the light is falling on one side of the plant, this hormone
auxin diffuses towards the shady side of the shoot and stimulates the
cells to grow longer.
4. On the other hand, the root system of the plants responds to the stimulus
of gravity and water. These responses are called gravitropic and
hydrotropic movements respectively.
5. The movement of plant part in response to certain chemicals.
Eg. The growth of pollen tubes towards the ovules.
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Answer the following questions in one sentence each :
Name the sense organs.
The sense organs are eyes, nose, ears, tongue, skin.
Where do you find the gustatory and olfactory receptors ?
Gustatory receptors are located on the tongue and olfactory receptors are
located in the nose.
What do the gustatory and olfactory receptors detect ?
Gustatory receptors detect tastes and olfactory receptors detect smell.
How are life processes controlled in unicellular amoeba ?
In unicellular amoeba, there is no nervous system. The cell is sensitive
enough to control its own life processes or activities.
How is the nerve cord formed in annelidans like earthworm ?
In annelidans like earthworm a number of nerve cells come together and
form a cluster. These clusters are joined together to form a beaded structure
called the nerve cord.
What is short term memory ?
Short term memory lasts only for 30 seconds. Eg. Remember a phone
number and dial it and then it vanishes from memory.
What is long term memory ?
Long term memory is the memory for things that we have carefully learned
and memorized.
What is a neuron ?
Neuron is a specialized cell capable of creating and transmitting
electrochemical impulses.
What is the function of hormones in arthropods ?
In arthropods, hormones induce colour changes and are influential in
regulating development.
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ACTIVITY BASED QUESTIONS
ACTIVITY : 11.1
Q.
Ans.
Take out from the refrigerator the polyethylene bag in which vegetables
are kept. After 5 minutes, remove the vegetables from the bag and feel
the inside of the bag. What is your observation ?
The inside of the bag feels moist. This is due to loss of water from the
vegetables. This loss of water is called transpiration.
ACTIVITY : 11.2
•
•
•
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•
Q.
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Take a shallow bottle with a wide mouth.
Put some moist cotton in it.
Place a few sprouted seeds on it.
Observe the directions of growth of radicle and plumule.
The radicle grows downwards and the plumule grows upwards.
Pick up one of the sprouts and place it in such a way that the radicle is
towards the source of light and the plumule is away from light.
Observe the directions of growth daily.
The radicle bends downwards and the plumule bends towards light.
What do you conclude from your observations ?
The radicle is the part which forms roots so it bends downwards towards
the stimulus of gravity and water whereas the plumule is the part which
forms the stem so it bends towards the source of light.
ACTIVITY : 11.3
•
Q.
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Q.
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Look for Mimosa plants in the garden or along the hedges. Touch the
leaves of this plant.
What do you observe ? What happens to them ?
The leaflets of Mimosa plant fold and droop down.
After half an hour, observe the same plant. Note down you observation.
The leaflets again unfold and return to their normal position.
ACTIVITY : 11.4
Q.
Ans.
An inter-house Basketball match is in progress at your school’s court.
List a few actions of the players where you observe control and coordination in their movements.
Control and co-ordination is observed in dodging the ball, jumping, running,
passing it to the team mate and dribbling the ball.
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Your pet dog Dollar is comfortably taking a nap. Go near him and drop a
stainless steel spoon on the floor. What do you observe ?
The dog startles and wakes up and his ear pinnae are raised.
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ACTIVITY : 11.6
Q.
List the endocrine glands present in human beings. Where are they
positioned in our body ? Consult books in the library to find out about
their functions.
Ans.
Sr.
Endocrine
No.
glands
1. Hypothalamus
2.
Pituitary
(Master gland)
Location
Hormones
Functions
Brain
Releasing
hormones
Regulation of the secretion of
hormones from the pituitary gland.
Base of
forebrain
Growth
hormones
Development of bones and tissues.
Trophic
hormones
Regulation of the secretion of
hormones from other endocrine
glands.
Prolactin
Regulation of the function of
mammary glands.
Vasopressin Regulation of water and electrolyte
balance.
Oxytocin
Stimulates contractions of smooth
muscles, helps in child birth and
lactation.
3.
Thyroid
Lower part of the Thyroxine
neck
4.
Adrenal
A pair of cap
shaped organs
above each
kidney
Adrenaline
and
Cortisone
Regulation of blood pressure, heart
rate. Carbohydrate metabolism and
mineral balance.
5.
Pancreas
In the curve of
the small
intestine
Insulin and
glucagon
Regulates sugar metabolism.
6.
Ovary
(In females)
Lie on the
lateral walls of
the pelvis
Oestrogen
Development of secondary sexual
and
characters. Eg. Development of
Progesterone breasts in female. Regulation of
menstrual cycle.
7.
Testis
(In males)
In the scrotum
Testosterone Development of secondary sexual
characters in male. (Masculine
features such as growth of
moustaches and beard.)
8.
Pineal
Near the center Melatonin
of the brain,
between the two
hemispheres
Its regulates the wake/sleep
patterns and seasonal functions.
9.
Thymus
Behind the
sternum and
above the
trachea and
heart
It stimulates the activity of the Tlymphocytes which are responsible
for invading organisms and killing
them.
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Thymosin
Regulates rate of growth and
metabolism.
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The plant which has fruits is seen bending towards sunlight. This
response of the plant to light is because of a hormone which is responsible
for ...
(a) helping the cells of the shoot to grow longer.
(b) helping the cells of the fruit to divide.
(c) helping the inhibition of growth of the part of the plant which is
directly in contact with the sunlight.
Helping the cells of the shoot to grow longer.
State whether afferent or efferent nerves would be responsible for
passing the impulses between the brain and sensory organs or muscles
or other body organs.
(a) My finger got burnt while cooking.
(b) The wild life photographer started running after the lion suddenly
jumped before him from nowhere.
(a) Afferent nerve carried the impulse from finger to the brain.
(b) Efferent nerve carried the impulse from brain to the muscles of the
leg.
In some of the plants, as a response to a stimulus, a small part of a
plant such as a leaf, alters its shape. Explain.
Various stimuli such as touch or an insect make some of the plants respond
by altering its shape. The information about the stimulus is passed on
from one cell to another with the help of electrical or chemical means.
Then, the alteration in shape or movement is brought about by changing
the amount of water inside the cells i.e. either by swelling or shrinking,
thus changing the shape. Hormones are mainly responsible cause for these
movements in the plant as a response to the stimuli.
Look at the following actions. Write the name of that part of the brain
which controls them.
(a) Riding a bicycle
(b) Sneezing
(c) Thinking
(d) Speaking
(e) Artistic abilities.
(a) Hind brain – Cerebellum.
(b) Hind brain – Medulla oblongata.
(c) Fore brain – Cerebellum.
(d) Left part of the brain.
(e) Right part of the brain.
Classify the following actions into voluntary and involuntary.
(a) Mr. Ajay’s blood pressure shot up after a fight with his neighbour.
(b) Shantanu was forced by his friends to tell a lie.
(a) Involuntary.
(b) Voluntary.
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The following statement is false. What is the truth ? Why ?
In human beings, in order to facilitate the secretion of hormones,
endocrine glands are placed in ducts.
Endocrine glands are ductlesss glands. They are also called as ‘glands of
secretion’. The hormone is secreted directly into the blood stream. This
provision is made to facilitate the transport of hormone to all the parts of
the body in order to activate necessary body organs in a short duration.
The hormone secreted is called as ‘chemical messenger’.
Evaluate the following situations and state if the movements were
controlled by central and peripheral nervous system or autonomous
nervous system :
(a) Ram bent down to pick up his books on the floor.
(b) My heart started beating very rapidly.
(c) He blinked when he had to face a sudden flash of light.
(d) Shyam was flying kite.
(e) Seema’s stomach was upset after eating stale food.
(a) Central and peripheral nervous system.
(b) Autonomous nervous system.
(c) Autonomous nervous system.
(d) Central and peripheral nervous system.
(e) Autonomous nervous system.
Imagine that you are given powers to bring out changes in the system
of plants. What should be done to ...
(a) stop the growth of the root towards water ?
(b) expedite the process of cell division ?
(a) Remove the hormone auxin which is responsible for the growth and
induce Abscissic acid which inhibits the growth of a plant.
(b) Induce the hormone cytokinins which promotes the cell division.
Give three names of animals in accordance with the advancement of
their nervous system. Justify.
(a) Amoeba. There is no nervous system at all. The cell carries out all the
functions.
(b) Any member of the family of annelids in which a number of nerve cells
come together to form a cluster called nerve cord. (E.g. Earthworm)
(c) Human beings in which a well developed nervous system is present
consisting of CNS (Central nervous system), PNS (Peripheral nervous
system), ANS (Autonomous nervous system).
What would happen if ...
(a) leaves a plant are coated with paint.
(b) animals loose the capacity of reflex action.
(c) plants lack Abscissic acid.
(d) peripheral and autonomous nervous systems are detached from each
other and from Central nervous system.
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(e) there appears malfunctioning in the mid and hind brain which
controls involuntary action in the body of animals.
(a) The stomata would get blocked. Transpiration of water and gases would
not happen resulting into death of the plant.
(b) They would not be able to defend themselves from emergencies resulting
into injury or death.
(c) Abscissic acid is a hormone responsible for inhibiting growth of the
plant. The plants would grow limitlessly. The leaves would not wilt.
(d) There would not be any co-ordination in the body of the animals and
their existence would be impossible.
(e) The heart would stop as its beating is an involuntary action. The
animals would be dead.
The movement of a plant organ in response to the stimulus of contact is
called thigmotropism. It is seen in plants which climb by means of tendrils
which are sensitive to the contact stimulus. Tendrils are found in plants
like Cucurbita and grapevine. Only the apical part of the tendril is sensitive
to contact.
Questions :
(a) What is thigmotropism ?
(b) Which plants show thigmotropism ?
(c) Give the names of any two plants which show tendrils.
(d) Which part of the tendril is sensitive to contact ?
(a) The movement of a plant organ in response to the stimulus of contact
is called thigmotropism.
(b) Thigmotropism is seen in plants which climb by means of tendrils.
(c) Plants such as Cucurbita and grapevine show tendrils.
(d) The apical part of the tendril is sensitive to contact.
Name the plant hormone :
(a) Which inhibits growth and causes wilting of leaves ?
(b) Which promotes cell division ?
(a) Abscissic acid.
(b) Cytokinins.
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CONCEPT MAP
Control and Co-ordination
Found in
Found in
Plants
Animals
helps in
Movement
is
Growth
dependent
Movement
is controlled by
Growth
independent
Nerves
Chemicals
hormones from
lead to
Spinal cord
Endocrine glands
sometimes influence
the action of
Brain
comprises of
controls
Forebrain
Mid brain
Hind brain
responsible
for
Reflex
Action
Voluntary
Action
Involuntary
Action
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Marks : 20
CHAPTER 11 : REGULATORS OF LIFE
Duration : 1 hr.
SCIENCE
Q.I
1.
2.
[A] Fill in the blanks :
..................... do not possess a nervous system.
Response to the stimulus of touch is called ..................... whereas
response to the stimulus of chemicals is called as ..................... .
Brain is the main ..................... centre of the body.
The loss of water from the plants is known as ..................... .
2
[B] Match the columns :
Column A
Column B
Gibberellins
(a) Promoting cell division in fruits and
seeds
Cytokinins
(b) Tip of shoot to grow longer
Abscissic acid
(c) Promoting growth of stem
Auxins
(d) Wilting of leaves
2
Q.I
1.
2.
3.
[C] Name the following :
Maintenance of steady state by different systems in an organism.
Cells those assist the neurons in their function.
The small gap between the consecutive neurons.
3
Q.II
1.
2.
Give scientific reasons : (Any Two)
Roots of plants go away from light.
Hormones secreted by the endocrine glands are present everywhere
in the body.
Insulin plays an important role in controlling the sugar level of blood.
4
Answer the following questions : (Any Two)
Write a note on Reflex action.
Write a note on Co-ordination in plants.
Distinguish between Voluntary and Involuntary movements.
What is tropic movement ? Describe the different types of tropic
movements.
4
3.
4.
Q.I
1.
2.
3.
4.
3.
Q.III
1.
2.
3.
4.
Q.IV Answer the following : (Any One)
1.
Describe chemical co-ordination in animals.
2.
Describe the conduction of nerve impulse.
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