define control and co-ordination

Control is the power of restrain and regulation by which something can be started,slowed down or stopped.

Co-ordination : the working together of various agents of the body of an organisms in a proper manner to produce appropriate reaction to a stimulus is called coordination.

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 The synchronization and integration of activities,responsibilities, and command and control structures toensure that the resources of an organization are used mostefficiently in pursuit of the specified objectives. Along withorganizing, monitoring, and controlling, coordinating is one of the key functions of management.

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Xth Notes 
   Control & Coordination

1. Which are the systems involved in the control and co-ordination in animals? 

The systems involved in the control and co-ordination in animals are the Nervous system, Muscular system and Endocrine system. 

2. Name the receptors of taste and smell. 

The receptor of taste is Gustatory receptor and that of smell is Olfactory receptor. 

3. What is a nerve impulse? 

The information passing through a neuron in the form of electrical and chemical signals is known as a Nerve Impulse. 

4. How does a nerve impulse travel through the body? 

The information acquired at 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. A similar synapse finally allows the delivery of such impulse from neurons to other cells such as muscles or glands. 

5. What is a synapse? 

A Synapse is a gap between two neurons. 

6. What happens at a synapse between two neurons? 

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. 

7. What is reflex action? Give examples. 

Reflex action is a quick involuntary response to a stimulus by an effector. 
i. Withdrawing our hand from a hot object. 
ii. Closing the eye when a moving object approaches the eye on a collision-course. 
iii. Blinking the eyelids when a moving object approaches the eye 
iv. Knee-jerk reflex. 

8. What is the difference between a reflex action and walking? 

Reflex action is an involuntary action whereas walking is a voluntary action.

9. Draw the structure of a neuron and explain its functions.
 Xth Notes  
 X Assignment  
 Crosswords for X  
 Neurons are specialized for conducting information via electrical impulses from one part of the body to the other. There are three types of neurons: 
Sensory neurons: Conducts nerve impulses from sense organs to the brain and spinal cord. 
Motor neurons: Conducts impulses from brain and spinal cord to the effectors, i.e. muscles and glands. 
Relay neurons: Between the sensory neurons and motor neurons.

10. Draw the neuro-muscular junction and label its parts.
 11.  Draw a labelled diagram of Brain. 
 12. Which part of the brain maintains posture and equilibrium of the body? 

Cerebellum maintains posture and equilibrium of the body. 

13. Write the functions of the following parts: 
i. Fore-brain 
ii. Cerebellum 
iii. Medulla 

i. 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 association areas where sensory information is interpreted by putting it together with the information from other receptors as well as with the information already stored in the memory of the brain. There are centers for motor areas for all muscles. Information about how to respond to the stimuli is passed on to these motor areas. 
ii. Cerebellum is responsible for precision of voluntary actions and maintaining posture and balance of the body. 
iii. Medulla controls the involuntary actions including salivation, vomiting, blood pressure, etc.

14. Outline the reflex arc.
 15. Draw a labelled diagram of a Reflex arc. 

16. How do we detect the smell of agarbathi or incense stick? 

The olfactory receptors in the nose detect smell by sending nerve impulses to the olfactory centre of the brain. 

17. What is the role of the brain in reflex action? 

Reflex actions take place without the conscious involvement of the brain. But some of these involuntary responses are controlled by the mid-brain and hind-brain. In spinal reflexes, quick responses are given but the information is sent to the brain. 

18. How are the brain and spinal cord protected? 

The brain is protected by the bony box – Cranium of the skull. The spinal cord is protected by the vertebral column. In addition to this, the brain and spinal cord are surrounded by membranes (meninges) which form a fluid filled around the brain. This provides further shock absorption. 

19. What is the function of receptors in our body? Think of the situations where receptors do not work properly. What problems are likely to occur? 

Receptors in our body receive stimuli and pass on the information to the central nervous system. If the receptors do not work properly, for example, if a person is blind or deaf information is not received by these receptors or is not conveyed to the brain and spinal cord. As a result, required responses are not given. 

20. How do animal muscles move? 

When a nerve impulse reaches the muscle, at the cellular level, the muscle cells will move by changing their shape so that they shorten. Muscle cells have special contractile proteins that change both their shape and arrangement in the cell in response to nervous electrical impulses. When this happens, a new arrangement of the proteins gives the muscle a shorter form. 

21. Which signals gets disrupted in the case of a spinal cord injury? 

Nerve impulses to and from different parts of the body below the part of the injury of the spinal cord will not travel to the brain. As a result, the body will be paralyzed depending on where the injury happened to the spinal cord. All reflexes also likewise stop.


1. How is the movement of the leaves of the sensitive plant different from the movement of a shoot towards light? 

Leaves of the sensitive plant move very quickly in response to touch. There is no growth involved in this movement. The directional movement of shoot towards light is slow and is caused by growth. If it is prevented from growth, it will not show the movement. In the movement of the leaves of sensitive plant, the stimulus is touch. In phototropism, the stimulus is light. Also, in sensitive plant, the movement is caused by the sudden loss of water from the swellings at the base of leaves. In phototropism the bending is caused by unequal growth on two sides of the shoot. 

2. What are plant hormones? 

Plant hormones are chemical substances. They are synthesized at places away from the place they act and simply diffuse into the area of action. They regulate germination, growth, flowering, ripening of fruits, causes phototropism, geotropism, hydrotropism, and chemotropism. 
E.g.: Auxins. 

3. Give examples of plant hormones which: 

i. Promote growth: Auxins & Gibberellins 
ii. Promote Cell Division: Cytokinnins 
iii. Inhibits Growth: Abscisic Acid 

4. How do Auxins promote the growth of a tendril around a support? 

When the tendril touches a support, auxin moves to the opposite side causing more growth on that side. This makes the tendril twine around the support. 

5. Design an experiment to demonstrate hydrotropism. 

i. Take two glass troughs A and B 
ii. Fill each one of them with two-thirds of soil 
iii. In trough B, we plant a similar seedling and place a small clay pot inside the soil. 
iv. Water the soil in the trough A daily and uniformly 
v. Do not water the soil in trough B, but put some water in the clay pot placed in the soil. 
vi. Leave both the troughs for a few days. 

On examining the roots later, it will be found that the root in trough B has bent towards the source of water. Roots in trough A grew normally straight.

6. How does phototropism occur in plants? 

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. 

7. How does chemical control & co-ordination occur in plants? 

In plant, control and co-ordination is done by chemical substances called hormones. They control growth, flowering, seed germination, ripening of fruits, Abscission of leaves and fruits, etc. 

8. What is the need for a system of control & co-ordination in organisms? 

The various physiological processes in an organism are closely linked and dependent on each other. The linking together of body activities in time and space is called co-ordination. Without co-ordination, the activities of the body would be thrown into a chaos and disorder. 
E.g.: When eating food at a meal, the position of food is recorded by the eyes and as a result of this information, the arms are moved to the right place to pick it up with precision and accuracy. As the food is raised to the mouth, the latter opens to receive it. Chewing movements commence and saliva is secreted. At the moment of swallowing, epiglottis closes the trachea and food is put into the esophagus. 

9. How are involuntary actions and reflex actions different from each other? 

Reflex actions are rapid automatic response to a stimulus without the conscious involvement of the brain. 
E.g.: Withdrawing the hand from a hot object. 
Involuntary actions are controlled by the brain but not by our conscious thinking. 
E.g.: Beating of the heart, peristaltic movement of the intestines. 

10. Compare and contrast the nervous and hormonal mechanism for control & co-ordination in animals.

Nervous System 
Nervous system has a network of nerves.
Nervous Impulses pass from the receptors to the control nervous system and then to the effectors, through nerve fibers. 
Nerve impulses reach only the cells required to respond.
There is no feed back mechanism in generating electrical impulses. 

Hormonal Mechanism 
Hormone system does not have such a network in the body. 
Hormones pass from the endocrine glands through blood. 
Hormones reach all the cells, but special cells on the target organs using special molecules on their surfaces recognize the information and act. 
The timing and amount of hormones released are dependent on feedback mechanism.

11. What are the differences between the manner in which movement takes place in a sensitive plant and the movement in our legs? 

The stimulus of touch causes the response in a sensitive plant. Drooping of the leaves takes place due to change in osmotic pressure at the base of the leaf. When the stimulus is over, the osmotic pressure increases causing the leaf to become normal. This is not a growth-related movement. It is not connected with the direction of stimulus. 

Nerve messages in the form of electrical impulse reaches the leg muscles from the brain. On reaching the leg muscles, the muscles contract the movement of the leg. 

12. How does chemical co-ordination take place in animals? 

Chemical co-ordination in animals takes place through hormones secreted by the endocrine glands. Hormones are transported by blood. When the hormone reaches the target organs, their cells have special molecules on their surface to detect this hormone. They recognize the information carried by the particular hormone and respond accordingly. 

13. Why is the use of iodized salt advisable? 

Iodine is important for the thyroid gland to make thyroxin hormone. Thyroxin regulates carbohydrates, proteins and fat metabolism in the body so as to provide the best balance for growth. If iodine is deficient in the diet, thyroxin cannot be produced and the thyroid gland at the neck swells, a condition called goiter. Use of iodized table-salt can provide the required amount of iodine in the diet. 

14. How does our body respond when the adrenaline hormone is secreted into the blood? 

i. The heart begins to beat faster resulting in supply of more oxygen to the muscles. 
ii. The blood to the digestive system and skin is reduced due to the contraction of muscles around small arteries in these organs. This diverts the blood to our skeletal muscles. 
iii. The breathing rate increases because of the contraction of the diaphragm and the rib muscles. 
iv. All these responses together enable the body to be ready to deal with the situation. 

15. Why are some patients of diabetes treated by giving injections of insulin? 

Insulin produced by the pancreas regulates the level of blood sugar glucose in the blood. When a person’s pancreas does not produce enough insulin, blood sugar level rises, resulting in a disease called diabetes. Such diabetic patients are given injections of insulin so that the sugar level in the blood can be controlled. 

16. Draw diagrams to show the position of endocrine glands in the body

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