Chapter 06 Control and Coordination Exercise
EXERCISES
1. Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin.
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Answer
(d) Cytokinin
2. The gap between two neurons is called a
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.
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Answer
(b) synapse.
3. The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
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Answer
(d) all of the above.
4. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
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Answer
Functions of receptors:
$\rightarrow$ They sense the external stimuli such as heat or pain.
$\rightarrow$ They also trigger an impulse in the sensory neuron which sends message to the spinal cord.
When the receptors are damaged, the external stimuli transferring signals to the brain are not felt. For example, in the case of damaged receptors, if we accidentally touch any hot object, then our hands might get burnt as damaged receptors cannot perceive the external stimuli of heat and pain.
5. Draw the structure of a neuron and explain its function.
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Answer
Functions of the three parts of a neuron:
$\rightarrow$ Axon: It conducts messages away from the cell body.
$\rightarrow$ Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.
$\rightarrow$ Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.
6. How does phototropism occur in plants?
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Answer
The growth movement in plants in response to light stimulus is known as phototropism. The shoots show positive phototropism and the roots show negative phototropism. This means that the shoots bend towards the source of light whereas the roots bend away from the light source. For Example: The flower head of sunflower is positively phototropic and hence it moves from east to west along with the sun.
7. Which signals will get disrupted in case of a spinal cord injury?
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Answer
In case of the spinal cord injury, the signals coming from the nerves as well as the signals coming to the receptors will be disrupted. As both these signals meet in a bundle in spinal cord so there is any spinal cord injury then both these signals are disrupted.
8. How does chemical coordination occur in plants?
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Answer
Chemical coordination occurs in plants with the help of plant hormones. Different plant hormones help to coordinate growth, development, and responses to the environment. They are synthesized at places away from where they act and diffuse to the area for action, For example, auxin promotes cell growth, gibberellins promote stem growth, cytokinins promote cell division and abscisic acid inhibits growth and its effects include wilting of leaves.
9. What is the need for a system of control and coordination in an organism?
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Answer
There are various organs in an organism. These organs must be carefully controlled and coordinated for the survival of an organisms. In the body of an organism various fluids are secreted from the glands of the endocrine system. These hormones are responsible for the overall growth and development of an organism. All others daily decision that includes voluntary and involuntary action are controlled by central nervous system(CNS).
10. How are involuntary actions and reflex actions different from each other?
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Answer
Involuntary action is the set of muscle movement which do not require thinking. But it is controlled by brain for example beating of heart beat while on the other hand, the reflex action is rapid and spontaneous action in response to any stimulus. For example closing of eyes immediately when bright light is focused.
11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
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Answer
| Nervous System Mechanism | Hormonal System Mechanism |
|---|---|
| It is consist of nerve impulses between PNS, CNS and Brain. | It consists of endocrine system which secretes hormones directly into blood. |
| The axons and dendrites transmit the information through a coordinated effort. | The information is transmitted or transported through blood. |
| The flow of information is rapid and the response is quick. | The information travels slowly and the response is slow. |
| Nerve impulses are not specific in their action. | Each hormone has specific actions. |
| Effects are short lived. | It has prolonged effects. |
12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
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Answer
| Movement in sensitive plants | Movement in our legs |
|---|---|
| The movement in a sensitive plant is a response to stimulus(touch) which is a involuntary action. | Movement in our legs is a voluntary action. |
| No special tissue is there for the transfer of information | A complete system CNS and PNS is there for the information exchange. |
| Plant cells do not have specialised protein for movements. | Animal cells have specialised protein which help muscles to contract. |
