1. Class X: Biology
Chapter 2: Control and Coordination
Drawings to be drawn in your note
Fig-1 human brain
Fig-2 neuron
Fig-3
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2. Fig-4 neuro muscular junction
1) Why control and coordination is essential in living organisms?
A system of control and coordination is essential in living organisms so that the different body parts
can function as a single unit to maintain homeostasis as well as respond to various stimuli.
2) What does a synapse do?
• It allows the information to pass from one neuron to another.
• It ensures the passage of nerve impulse in one direction only.
• It helps in information processing by combining the effects of all impulses received.
Or
Define synapse.
A synapse is the junction of the terminal branches of the axon of one neuron with the dendrites or cell
body of another neuron. It is the site of transfer of nerve impulse from one neuron to another.
3) How control and coordination is brought in animals?
In animals, the nervous system and hormonal system are responsible for control and coordination.
4) Define neurons.
Neurons are specialized cells of the nervous system. They use electrical and chemical signals for
transferring information.
5) Define receptors.
Receptors are specialized tips of the nerve fibres that collect the information to be conducted by the
nerves.
6) Show the pathway for nerve impulse conduction in neurons.
Nerve impulses travel in the following manner from one neuron to the
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3. next : Dendrites _ Cell body _ Axon _ Nerve endings at the
tip of axon _ Synapse _ Dendrite of next neuron.
7) Briefly explain the process of nerve impulse conduction by neurons.
Chemicals released from axon tip of one neuron, cross the synapse or neuromuscular junction to
reach the next cell (neuron or muscle fibre).
8) Identify 2 parts of our nervous system.
Central nervous system and peripheral nervous system are parts of our nervous system.
9) What is meant by central nervous system?
Central nervous system is made up of the brain and spinal cord.
10) Give the importance of spinal cord during reflex action.
Spinal cord controls the reflex actions and conducts messages between different parts of the body
and brain.
11) Define reflex action.
Reflex action is an automatic, rapid and immediate reaction to a stimulus and is below the level of
consciousness. No thinking is involved in reflex action.
Or
A reflex action may be defined as a spontaneous, autonomic and mechanical response to a stimulus
controlled by the spinal cord without the involvement of brain.
12) Define reflex arc. Show the pathway of reflex arc.
Reflex arc is the neural pathway that mediates a reflex action.
Pathway of reflex arc: Receptor _ Sensory neuron _ Relay neuron _ Motor neuron _ Effector
Or
Stimulus received by the sensory receptors in the sensory organ
Impulse generated and carried along by the sensory neuron toward the spinal cord
Impulse arrives at the nerve endings of sensory neuron in the grey Matter of spinal cord
Neurotransmitter released at nerve endings
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4. Impulse pass across the relay neuron to motor neuron
Impulse travels away from spinal cord along motor neuron
The nerve endings of motor neuron connect effector organ like muscle
Response produced by effector organ
Fig. 28.10 Sequence of events in a reflex arc
13) What is the role of spinal cord and brain in the reflex action?
The sensory neurons of reflex arcs synapse in the spinal cord which then activates the spinal motor
neurons without delay to execute a quick action, especially in case of emergencies. The brain also
receives the information while the reflex action occurs.
14) What are the 3 parts of human brain?
The 3 main parts of the brain are forebrain, midbrain and hindbrain.
15) Identify the regions in forebrain and hindbrain.
The largest part of the brain, the forebrain, is the main thinking region. It is made up of cerebrum,
hypothalamus and thalamus. Cerebellum, pons and medulla constitute the hindbrain.
16) Which the first and second largest part in human brain?
Cerebrum is the largest part of the brain whereas the cerebellum is the second largest part.
17) Give the parts of the brain and their functions.
Part of brain Function
Cerebrum Governs intelligence, thinking, memory and other mental abilities,
voluntary actions, sensations, emotions and speech.
Hypothalamu
s
Coordinates messages from the autonomous nervous system, controls
certain involuntary actions, as well as emotional behavior and forms an
axis with the pituitary.
Thalamus Functions as major coordinating center for sensory and motor
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5. signaling.
Midbrain Acts as the coordinating centre between forebrain and hindbrain; also
controls certain involuntary movements
Cerebellum Responsible for precision and fine control of voluntary movements as
well as maintaining posture and equilibrium of the body
Pons Relays impulses between the lower cerebellum and spinal cord, and
higher parts of the brain like the cerebrum and mid brain; also
regulates respiration.
Medulla Contains vital centres for controlling blood pressure, respiration,
swallowing, salivation, vomiting, sneezing and coughing.
18) How our brain is protected?
Brain is protected by a bony box called cranium, within which are present 3 layers of fluid-filled
membranes for absorbing shock.
19) Identify the components of peripheral nervous system.
Peripheral nervous system consists of cranial nerves and spinal nerves
and assists in transmitting information between central nervous
system and rest of the body.
20) Can you state few responses shown by our nervous system?
Reflex actions, voluntary actions and involuntary actions are the various types of responses shown by
the nervous system.
21) What is the role of central nervous system in muscular movements?
The sense organs detect changes in surroundings and pass this information to the central nervous
system, which after processing the information, acts through the muscles.
22) How muscles tissues can make their movement?
The movements of muscle tissues are brought about by the contraction and relaxation of the
contractile proteins in response to nerve impulses.
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6. 23) Do plants have any nervous and muscular system for signal condution?
No, plants lack nervous and muscular system.
24) What are the ways plants will respond to stimuli?
Plants respond to stimuli by showing 2 types of movements – growth independent and growth
dependent.
25) What kind of movement is taking place in touch-me-not plant?
In the case of touch-me-not plant growth independent movements are usually quicker than growth
dependent ones, and involve the use of electrochemical signals by the plant. To achieve this
movement, the plant cells change shape by altering their water content.
26) Give few characteristics of growth dependent movements.
Growth dependent movements or tropic movements are slow, occurring either towards or away from
the stimulus.
27) Identify few factors in the environment which leads to tropic movements in plants.
Tropic movements are shown in response to environmental factors such as light, gravity, water and
chemicals.
28) Compare plant roots and plant shoots.
Plant roots are positively geotropic and negatively phototropic whereas plant shoots are usually
negatively geotropic and positively phototropic.
29) Specify one chemotropic movement in plants.
Pollen tubes show chemotropism by growing towards the ovules.
30) What is the other form of signal used by plants and animals other than electro chemical
signals?
In addition to electrochemical signals, plants and animals use hormones for control and coordination.
31) List some Important plant hormones and their functions.
Plant hormone Function
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7. Auxin Cell elongation during growth of shoot region.
Gibberellin Growth of stem
Cytokinin Cell division
Abscisic acid Inhibits growth
Ethylene Ripening of fruits
32) What causes bending of plant stem towards light?
Auxin causes the bending of plant stem towards light as well as the
curling of plant tendrils around a support.
33) Is animal hormones can bring any directional growth?
Animal hormones do not bring about directional growth depending on environmental cues, but
promote controlled growth in various areas to maintain the body design.
34) Mention some names of endocrine glands in the human body.
The various endocrine glands in humans are hypothalamus, pineal gland, pituitary gland, thyroid
gland, parathyroid glands, thymus, pancreas, adrenal glands, ovary (in female) and testis (in males).
35) Mention some important hormones and their functions in human body:
Hormone Endocrine
gland
Function
Growth
hormone
Pituitary Regulates growth and development of body
Thyroxin Thyroid gland Controls carbohydrate, protein and fat
Metabolism
Adrenaline Adrenal gland Prepares the body to deal with emergency
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8. situations
Insulin Pancreas Regulates blood sugar levels
Testosterone Testis Causes development of sexual organs and
secondary sexual characteristics in males
Oestrogen Ovary Causes development of sexual organs and
secondary sexual characteristics in females
35) Show the pathway for effect of adrenal hormones during emergency.
In case of flight or fight reaction to an emergency situation,
Adrenal glands _ release adrenaline into blood _ which acts on heart
and other tissues _ causes faster heart beat _ more oxygen to
muscles _ reduced blood supply to digestive system and skin _
diversion of blood to skeletal muscles _ increase in breathing rate.
36) Identify the element deficiency which is related to thyroid function. Mention the problems
due to its deficiency.
Deficiency of iodine causes goiter whereas deficiency of growth
hormone and insulin causes dwarfism and diabetes respectively.
37)How hormones can be controlled?
Feedback mechanisms are present to regulate the hormone action.
38) Give the difference between nervous and endocrine system
Nervous system Endocrine system
Mode of communication- Electrical
impulses
Mode of communication - Chemical
compounds
Speed of communication - Very quick Slow
Can reach Only cells connected by
Very fast way of communications. All cells of
the body can receive the messages.
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9. nervous system.
Continuity - Cannot continuously transmit
impulses.
Continuity - Can act steadily and persistently
39. What are the functions of cerebrum?
The cerebrum performs the following functions:
i. It governs our mental abilities like thinking, reasoning, learning, memorising
and intelligence.
ii. It controls our will, emotions and speech.
iii. It controls feeling of love, admiration and hatred.
iv. It controls all involuntary functions.
40. What are the functions of cerebellum?
The cerebellum performs the following functions:
i. It maintains equilibrium (balance) of the body.
ii. It controls posture of the body.
iii. It coordinates muscular movement.
41. What is the importance of Medulla.
It is the lowermost part of the brain located at the base of the skull.
The medulla oblongata performs the following functions:
i. It controls the internal organs like movement of lungs, heart etc., by regulating breathing and heart-
beat.
ii. It controls vital reflex centres such as cardiac centre, respiratory centre and centres for swallowing,
sneezing, coughing and vomiting.
42. Mention the functions of spinal cord.
The spinal cord performs the following functions:
i. It controls the reflexes below the neck region.
ii. It conducts sensory impulses from the skin and muscles to the brain.
iii. It conducts motor response from brain to the muscles of trunk and limbs.
43. What are sense organs?
Sense organs are the organs through which we sense or feel change in the external environment.
44. What are hormones?
A hormone is a chemical secreted by an endocrine gland and carried by blood
or lymph to a target organ elsewhere in the body to stimulate a specific activity.
45. Locate the endocrine glands
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10. Fill in the blanks.
i) The central nervous system consists of _________ and ___________
ii) Pathway meant for transmission of the message from the receptors to
modulators is called _____________ pathway.
iii) ___________________ nerves carry impulse from brain or spinal cord
to the effectors.
iv) The stimulus from the receptor organ is received by the __________,
conducted to the cell body of neuron and finally to the __________
organ.
v) A synapse is the point of contact between the terminal branches of the
_________ of one neuron with the _________ of another neuron.
Fill in the blanks
i. __________ carry information from sensory receptors to central nervous
system.
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11. ii. __________________ system receives and processes information from
receptors in the skin, voluntary muscles and eyes.
iii. The pathway followed by sensory or motor nerves in a reflex action is
called __________________
A hormone is carried by _________ or ________ to the target organ.
iv) Thyroid stimulating hormone is secreted by ___________
v) ________ hormone regulates the conversion of glucose to glycogen.
vi) ___________________ hormone controls the reabsorption of water in
kidney tubules.
vii) Hypoactivity of thyroid gland leads to__________
Multiple choice type questions.
Tick the most appropriate answer of the following.
1. Which of the following carry impulse from brain to effector?
a) Sensory neuron b) Motor neuron
c) Connecting neuron d) Mixed nerve
2. Short thread like branches of nerve cell are called
a) dendrites b) synapse
c) nodes of Ranvier d) neuron
3. A chemical known as neurotransmitter is released from the ends of
a) axon b) synapse
c) nodes of Ranvier d) neuron
4. The pituitary gland is found
a) in the neck b) at the base of the brain
c) beneath the stomach d) near the kidneys
5. The transparent window at the front of the eyeball is called
a) cornea b) iris
c) cone d) retina
6. Hormones are carried around in the body by
a) blood b) nerves
c) lymph d) both blood and lymph
7. Which of the following glands secretes the hormone thyroxin?
a) Pituitary gland b) Thyroid gland
c) Brain d) Pancreas
8. Which of the following hormones is secreted by the pancreas?
a) Growth hormone b) Thyroxin
c) Insulin d) Prolactin
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12. 9. The disease cretinism is caused due to
a) hypoactivity of pituitary gland b) hyperactivity of pituitary gland
c) hypoactivity of thyroid gland d) hyperactivity of thyroid gland
10. Hyposecretion of insulin causes
a) Goitre b) Cretinism
c) Diabetes insipidus d) Diabetes mellitus
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