GRADE 10- BIOLOGY WORKSHEET
CONTROL AND CO-ORDINATION
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. 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.
8. 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.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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.
14. 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.
15. Give examples of plant hormones which:
i. Promote growth: Auxins& Gibberellins
ii. Promote Cell Division: Cytokinins
iii. Inhibits Growth: Abscisic Acid
16. 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.
17. 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.
18. 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.
19. 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.
20. 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 coordination. 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.
21. 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.
22. Compare and contrast the nervous and hormonal mechanism for control & coordination 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.
23. 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.
24. 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.
25. Why is the use of iodized salt advisable?
Iodine is important for the thyroid gland to make thyroxin hormone. Thyroxine 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, thyroxine 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.
26. 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.
27. 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.
ENDOCRINE GLANDS AND HORMONES
1 Hypothalamus
Releasing hormones
Regulates the secretion of hormones from the pituitary gland
2 Pituitary
Growth hormone
Regulates the growth and development of bones and muscles
3 Pineal gland
Melatonin
Affects the modulation of wake/sleep patterns and seasonal functions
4 Thyroid gland
thyroxine
Regulates the metabolism of carbohydrates, fats and proteins in the body so as
to provide the best balance for growth.
5 Parathyroid gland
calcitonin
Regulates the level of calcium and phosphate in the blood.
6 Adrenal gland
adrenaline
Responds to cold, joy, anger, fear and emotional stress, increases blood supply
to heart and skeletal muscles, rate of breathing ,reduces blood supply to skin
and digestive system
7 Thymus gland
Thymosin
Activates immune responses and helps in the production of antibodies.
8 Pancreas
insulin
Regulates blood sugar level
9 testes
Testosterone
Regulates development of male accessory sex organs and induces secondary
sexual characteristics
10 ovary
Estrogen
progesterone
Regulates development of female accessory sex organs and secondary sexual
characteristics Essential for maintaining pregnancy.
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