1. (d) Cytokinin.
2. (b) Synapse.
3. (d) All the above.
4. Receptors detect all the information from our environment. These receptors are
located in our sense organs.
In case any of the receptors do not work properly we will not be able to perceive that particular information.
5. Neuron acquires particular information through dendrite located on its cell body. This information is then passed on to the axon. Finally, axon ending passes the information into next neuron at the synapse. As soon as the impulse reaches the dendrite, an electrical impulse is generated due to certain chemical changes in neuron. When the impulse reaches axon ending some chemicals released which pass on the impulse to next neuron. These chemicals are known as neurotransmitters.
6. Movement of shoot towards light is called phototropism. This movement is caused due to more growth of cells towards the shaded side of the shoot as compared to the side of shoot towards light. More growth of cells is due to secretion of auxin towards the shaded side.
7. (i) Reflex action
(ii) Impulses from various body parts will not conducted to brain.
(iii) Message from brain will not be conducted to various organs.
8. Chemical coordination in plants is maintained by plant hormones also known as phytohormones. Some of these hormones promote growth while some inhibit it. Some hormones include auxin, Gibberellins, Cytokinin etc.
9. An organism has different organs which perform various factions. The survival of an organism depends on integrated and coordinated functions of these organs. Nervous and endocrine system of an organism makes them work together like parts of one machine to accomplish homeostasis or coordination.
10. Difference between involuntary and reflex actions is as follows:
Involuntary actions: It is a set of muscles movement over which we do not have control. Such actions are controlled by brain. For example- contraction of muscle of our digestive tract, beating of heart etc.
Reflex actions: It is rapid, spontaneous and involuntary activity that is produced in response to a stimulus. It is controlled by spinal cord. Example- removal of hand with jerk when someone touches a hot object.
11. Difference between nervous control and hormonal control:
(i) Consists of nerve impulses conducted by neurons from one organ to another organ.
(ii) Nervous impulses produce rapid short lasting responses.
(iii) Nervous impulses are not specific in their action.
(i) It consists of endocrine system which scretes chemical messengers hormones secreted directly in blood.
(ii) Hormones produce longer lasting responses.
(iii)Action of hormones is highly Specific.
12. Difference between movement in a sensitive plant and movement in our legs:
Movement in sensitive plant:
(i) There is no specialized tissue in plants for conduction of information.
(ii) Plant cells change shape by changing the amount of water in them.
(iii) Plant cells do not have specialized proteins.
Movement in our legs:
(i) There is specialized nervous tissue in animals for conduction of information
and muscle cells to help in movement.
(ii) Muscle cells contract or relax to effect movement.
(iii) Muscle cells have specialized protein which help muscles to contract or relax.
13. Difference between reflex action and walking:
(a) Take place without thought.
(b)Controlled by spinal cord.
(c) It is involuntary action
(a) Takes place after thought.
(b) Controlled by cerebellum.
(c) It is a voluntary action.
14. At synapse, the electrical impulse generated a dendrite of a neuron is passed on to dendrite of another neuron in form of chemical impulses. The chemical present at synapse is called neurotransmier.
16. Smell of agarbatti is detected by olfactory receptors in the temporal lobe of fore It is first received by olfactory receptors in our nose.
17. Reflex arcs are formed in the spinal cord itself although the information also goes on to brain where the encounter remains the memory and make us aware of our action.
18. They are chemical which help to coordinate growth, development, flowering and response to the environment in plants.
19. Difference between movement of leaves of sensitive plants and movement of shoot towards light:
Movement of leaves of sensitive plant:
(a) Growth is not involved.
(b) Movement is away from the source of stimulus (touch).
Movement of shoot towards light:
(a) Growth is involved.
(b) Movement is towards the source of stimulus (light).
20. Auxin promotes growth of cells.
21. When tendrils come in contact of any support, the part of the tendril in contact does not grow as rapidly as the part away from the object due to auxin secreted moves away from the object in contact. This rapid growth on one side causes tendril to circle around the object.
22. Take a tin box with hole at bottom. Fill it with moist saw dust. Sow some gram seeds in it. Keep the tin box in tilted position. When seeds start germinating, water the saw dust only in lower side of the tin box. You will observe that the radicle move towards the wet saw dust. This shows that root is positively hydrotropic.
23. The chemical coordination is maintained by hormones. These are secreted by endocrine glands. These hormones are poured into blood through which they reach the target tissue or organ to act.
24. Iodine is necessary for the thyroid gland to make thyroxin hormone. In case, iodine is absent in our diet, there is a possibility of Goitre. Iodised common salt contains proper content of iodine. To avoid deficiency of iodine, iodised salt is recommended.
25. When adrenaline reaches the various target organ through blood. All these organs respond together to enable our body to deal with situation like running away from scary situation. When adrenaline reaches the heart, it beats faster to supply more oxygen to our muscles. The small arteries around digestive system and skins contracts to divert the blood towards muscles. All these response enable our body to deal with situation.
26. Diabetes is caused due to non or less secretion of hormone insulin by pancreas. In such person, the blood sugar level is high. Insulin converts extra sugar present in blood into glycogen. Patients suffering from diabetes are given insulin injection to control their blood sugar level.