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Tenth Biology
Control and Coordination
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I. Conceptual Understanding
Reaching for a pencil, grasping a doorknob, walking or running, driving
etc., involve some movements. What are they?
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A: Whenever we move the three basic functions, movement, balance, and
coordination work together to produce purposeful motions of body parts.
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Give some examples of responses to stimuli.
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A: ★ The cat may be running because it has seen a mouse.
★ Plants grow out into the sunshine.
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★ We start sweating when it is hot and humid.
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II. Asking Questions and Making Hypothesis
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Imagine yourself to be Galan, the Greek physiologist (A.D.129 - 200). One
day a patient came to you and told that he had fallen from his chariot and
had a blow in the neck. He complained of loss of feeling in the arm while still
retaining normal muscular control of its moment. What questions would
arise in your mind to make any conclusions about the situation?
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A: If I were Galan, I would think on following questions:
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1. Is it the nervous system that is damaged?
2. Why is it that the blow in the neck resulted in the loss of feeling?
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3. If the nervous system is affected, how is it that there is normalcy in muscular
control of its movement?
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4. Are there different types of nerves for feeling and muscular movement?
5. What should I do to the patient to normalize his situation?
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III. Experimentation and Field Investigation
Touch the leaves of Mimosa pudica (Touch me not plant) and observe how
the leaves respond. Write your observations.
A: I went into a botanical garden and observed Mimosa pudica.
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The plant looks like this:
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★ When I touched the leaves of the plant, I observed that the plant folded up its
leaves.
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★ Then I observed the plant carefully and noted down my observations:
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Observations:
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★ Mymosa pudica leaves has pad like swellings at the base.
★ Here cells contain lot of water and large inter cellular spaces.
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★ Due to water pressure pulvini hold the leaf erect.
★ Touch me not plant shows nastic movement by touch. This is called
thigmonasty.
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★ When we touch the leaves an electrical impulse is generated. This impulse acts
on plant hormone. Because of this hormone water in the pulvini cells which
are closer to the leaf vein migrate to other side of the cells then pulvini loss its
firmness leaves become fold.
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★ After 20 to 30 minutes water comes back. Pulvini gets firm and leaves become
erect.
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IV. Information Skills and Projects
What is Tropism? Explain in a tabular form.
A: Tropism is a biological phenomenon, indicating growth or turning movement a
plant makes in response to an environmental stimulus.
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Name of the
How it functions
tropism & Picture
Phototropism
Movement of plants toward light to maximize
amount of sun for photosynthesis to make their
food.
Movement of plants in response to gravity.
Gravitropism
Positive is toward gravity (roots).
Negative is away from gravity (shoot: stems and
leaves).
Hydrotropism Movement by plants towards water.
Seen in roots 'searching' and growing toward water
which is needed for photosynthesis and to support
cell structure.
Thigmotropism
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Plants moving in response to touch.
Seen in vine plants as they wrap around other plants
or structures to support leaves as they grow higher
and higher to reach the sun to make more food
(photosynthesis).
Write the functions of various parts of the brain.
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Parts of the brain
Functions
Cerebrum
i) Seat of mental abilities, controls thinking, memory,
reasoning, preparation, emotions and speech.
ii) Interprets sensations and responds to cold, heat, pain
and pressure.
Diencephalon
i) Relay centre for sensory impulses, such as pain,
temperature and light.
ii) Reflex centre for muscular activities.
iii) Centre for certain emotions such as anger.
iv) Centre for water balance, blood pressure, body
temperature, sleep and hunger.
v) The hypothalamus controls the pituitary gland, which
functions as the master gland.
Midbrain
★ It relays motor impulses from the cerebral cortex to the
spinal cord and relays sensory impulses from the spinal
cord to the thalamus, reflexes for sight and hearing.
Cerebellum
i) Maintains posture, equilibrium and muscle tone.
ii) Coordinates voluntary movements initiated by
cerebrum.
Medulla oblongata
i) Contains centre for cardiac, respiratory and vasomotor
activities. (Vasomotor refers to actions upon a blood
vessel which alter its diameter).
ii) Coordinates reflexes like swallowing, coughing,
sneezing and vomiting.
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V. Communication Through Drawing, Model Making
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Draw a neat labeled diagram of brain and answer the following questions:
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1. What is the bony box that contains the brain called?
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2. What is it that extends from the back of the hind brain?
3. What does central nervous system comprise of?
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A:
Cerebral hemisphere
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Corpus callosum
Brain cavity
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Pituitary gland
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Medulla
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Mid brain
Cerebellum
Spinal cord
Brain
1. Crainium
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2. Spinal cord
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3. Brain and Spinal cord.
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VI. Appreciation and Aesthetic Sense, Values
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What does this picture denote?
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A: It is a synapse. Dendrites of one nerve cell connect to the other or to the axons of
the other nerve cell through connections called as a 'synapse'.
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★ Synapse is the connections between neurons. Synapse is a functional region
between two neurons where information from one neuron is transmitted or
relayed to another neuron.
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VII. Application to Daily life, Concern to Biodiversity
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How are responses brought about in our body?
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A: Responses are brought about by rapid changes in some muscles and such changes
are usually related to changing stimuli. Rapidity of response indicates an efficient
communication system linking those parts that pick up stimuli to those that
elicit a response.
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Give an example for the functions of autonomic nervous system in our
activities.
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A: Example: When we enter a dark room we cannot see anything immediately.
Slowly we are able to see the things around us in the room. This is because of
increase in diameter of pupil, which allows more light in. When we come out of
the dark room into broad day light the diameter of the pupil decreases allowing
less light to enter into the eyes. Both these functions occur under the influence of
the autonomic nervous system.
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Writer: K. Vijaya Bhanu
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