Ans. Such tips are called receptors. They are located in sense organs
2. Name the sensory receptors found in the nose and on the tongue ?
Ans. Olfactory receptors and gustatory receptors.
3. Name the part of the brain which controls posture and balance of the body. Ans. Cerebellum.
4. Give one example of chemotropism.
Ans. The growth of pollen tube towards ovule.
5. Name the two components of central nervous systems in humans.
Ans. Brain and Spinal Cord.
6. Name the largest cell present in human body.
7. How do the shoot and roots of a plant respond to the pull of earth s gravity?
Ans. Roots grow downward towards gravity while shoot usually grows upwards and away from earth.
8. Give reason to explain why endocrine glands release their secretions into the blood directly.
Ans. Hormones are secreted by endocrine glands. These glands do not have ducts to carry these hormones, so they are released directly in the blood stream that carries them to target organ.
9. What is synapse ?
Ans. The junction between neurons is called synapse.
10. A boy runs on seeing a stray dog. His breathing becomes very fast and blood pressure also increases. Name the hormone found to be high in his blood and the gland which produces it.
Ans. Adrenaline, Adrenal gland.
11. What is meant by Tropic movements ?
Ans. Plant growth movements in response to stimuli from a particular direction are called tropic movements.
12. While watering a rose plant, a thorn pricked Rita s hand. How would she respond to this situation Provide the term for such type of response?
Ans. She will withdraw her hand immediately. The name of the response is Reflex action.
13. Name the part of the neuron where information is acquired. Ans. Dendrite.
14. Name the part of neuron through which the information travels as an electric impulse.
15. Name the mechanism by which amount of hormone in the blood is regulated.
Ans. Feedback mechanism.
16. Name two tissues which provide control and co-ordination in animals.
Ans. Nervous and muscular tissues.
17. Name the diseases by which a person is likely to suffer due to the deficiency of (a) Iodine (b) Insulin
Ans. (a) Goitre (b) Diabetes
Short Answer Type Questions (2/3 marks each)
Q. 1. State the role of brain in reflex action.
Ans. The sensory area of brain receives information, interprets it and makes a rapid decision in the form of electrical impulses and sends it to receptor organ.
2. How does our body maintain blood sugar level?
Ans. If sugar levels in blood rises, cells of pancreas detect and secrete more insulin which leads to fall off sugar level.
3. What happens at the synapse between two neurons?
Ans. When an electrical signal reaches the axonal end of one neuron it releases chemical substances called
Neurotransmitter that cross the synapse and move towards the dendrite end of next neuron generating another electrical signal.
4. Name the hormone responsible for the regulation of
(i) metabolism of carbohydrates, fats and proteins,
(ii) balance of calcium and phosphate,
(iii) blood pressure,
(iv) water and electrolyte balance.
Ans. (i) Thyroxine (ii) Parathormone (iii) Adrenaline
(iv) Vasopressin or ADH (Antidiuretic hormone)
5. Write the name and functions of any two parts of brain.
Ans. The brain has three main parts. They are fore brain, mid brain and hind brain.
i) Fore brain: - It consists of the cerebrum and olfactory lobes. It is the thinking part of the brain and controls voluntary actions. It controls mental activities like thinking, learning, memory, emotions etc(cerebrum). and touch, smell, hearing, taste, sight(olfactory lobes).
ii) Mid brain :- It connects Fore brain and Hind brain. it controls involuntary actions and reflex movements of head, neck, eyes and ear etc.
iii) Hind brain :- it connects the Fore brain & Hind brain . it consists of cerebellum, pons and medulla.
Cerebellum :- controls body muscular movements , balance and posture
Pons :- it acts as a bridge between brain & spinal cord and controls respiration.
Medulla: - it controls involuntary action like heart beat, blood pressure, swallowing, coughing, sneezing, vomiting etc.
d) Spinal cord: - The spinal cord starts from the brain and extends through the vertebral column. It has 31 pairs of spinal nerves. It carries messages to and from the brain.
It also controls reflex actions. Cylindrical or tubular structure extending downwards from the Medulla oblongata.
6. Explain with the help of an example how the timing and amount of hormone released are regulated?
Ans. The timing and amount of hormone released are regulated by feedback mechanisms. For e.g. when there is rise in sugar level in blood, insulin secreted by pancreas. If sugar lavel in blood fall , insulin secretion is reduced.
7. (a) Which structures protect the spinal cord and brain ? (b) Write an activity to show phototropism and geotropism. (c) What type of movement is shown by mimosa plant leaves when touched with a finger?
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