Very Short Answer Questions
1. Write the function of thyroxine hormone in our bodies.
Ans. It controls basal metabolic rate and regulates metabolism of carbohydrates, fats and proteins.
2. What is neuron ?
Ans. Neuron or nerve cell is a structural and functional unit of nervous system that is specialized to receive, conduct and transmit impulses.
3. What is meant by tropic movements ?
Ans. Tropic movements are directional paratonic cuvature movements of growth which generally occur in cylindrical organs with direction of movement being determined by the direction of stimulus.
4. Define chemotropism.
Ans. Chemotropism is directional growth movement of curvature that occurs in response to a chemical stimulus. Ex. movement of pollen tube in style.
5. What is synapse?
Ans. Synapse is a narrow fluid-filled gap which functions as communicating junction between axon end of one neuron and dendrite tip of next neuron.
6. Define reflex action.
Ans. It is an automatic, spontaneous nerve mediated response to a stimulus without consulting the will of the individual.
7. Why is the use of iodised salt advisable ?
Ans. Iodine is an essential component of diet as it is required for synthesis of hormone thyroxine needed for proper metabolism of protein, fat carbohydrates. Deficiency causes goiter, cretinism and myxoedema.
8. How shoot and root of a plant respond to light ?
Ans. Shoot. It is positively phototrophic to unilateral light.
Root. It is either neutral or negatively phototrophic to unilateral light.
9. Mention the function of adrenaline hormone.
Ans. To prepare the body for meeting an emergency.
10. Name the part of the neuron where information is acquired.
Ans. Dendrite.
3. What is meant by tropic movements ?
Ans. Tropic movements are directional paratonic cuvature movements of growth which generally occur in cylindrical organs with direction of movement being determined by the direction of stimulus.
4. Define chemotropism.
Ans. Chemotropism is directional growth movement of curvature that occurs in response to a chemical stimulus. Ex. movement of pollen tube in style.
5. What is synapse?
Ans. Synapse is a narrow fluid-filled gap which functions as communicating junction between axon end of one neuron and dendrite tip of next neuron.
6. Define reflex action.
Ans. It is an automatic, spontaneous nerve mediated response to a stimulus without consulting the will of the individual.
7. Why is the use of iodised salt advisable ?
Ans. Iodine is an essential component of diet as it is required for synthesis of hormone thyroxine needed for proper metabolism of protein, fat carbohydrates. Deficiency causes goiter, cretinism and myxoedema.
8. How shoot and root of a plant respond to light ?
Ans. Shoot. It is positively phototrophic to unilateral light.
Root. It is either neutral or negatively phototrophic to unilateral light.
9. Mention the function of adrenaline hormone.
Ans. To prepare the body for meeting an emergency.
10. Name the part of the neuron where information is acquired.
Ans. Dendrite.
Short Answer Questions
1. What is hydrotropism ?
Ans. Hydrotropism is directional movement of curvature which occurs in response to stimulus of water.
2. (a) What is tropism ?
(b) How is brain protected in our body ?
(c) Name the part of brain responsible for precision of voluntary actions and maintaining body posture and balance of the body.
Ans. (a) Tropism. It is the phenomenon of directional paratonic growth movement of curvature in which the direction of movement is determined by the direction of stimulus, e.g., phototropism, geotropism, hydrotropism.
(b) (i) Bony box or skull on the outside. (ii) Meninges over the brain. (iii) Presence of cerebrospinal fluid both outside and inside the brain to absorbs shocks.
(c) Cerebellum.
3. Two examples of plant movement are shown
(a) State the stimulus which is common for movement in both the cases
(b) Mention separately for both, whether the movement takes place away or at the point where stimulus is received.
(c) State one reason for movement in each case.
Ans. (a) Stimulus. Touch
(b) In sensitive Plant, the leave shows movement away from place of contact, at the bases of pinnules, pinnae and petiole. In tendril the movement takes place in the region of contact.
(c) In sensitive Plant movement occurs due to loss of water or turgidity by certain cells. In tendril it is due to auxin induced greater growth of cells on the side not in contact with object.
4. How does the plant shoots bends when the plant is placed in a room having only one open window? Explain briefly.
Ans. The plant will be receiving light from one side. The unidirectional light causes positive phototrophic response from the shoot. More auxin is formed on the shaded side of the shoot apex. As a result more growth occurs on the shaded side than the illuminated side. This results in bending of the shoot towards the direction of light.
5. Give an example of a plant hormone that promotes growth ?
Ans. Indole 3-acetic acid or IAA (auxin).
Ans. (a) Tropism. It is the phenomenon of directional paratonic growth movement of curvature in which the direction of movement is determined by the direction of stimulus, e.g., phototropism, geotropism, hydrotropism.
(b) (i) Bony box or skull on the outside. (ii) Meninges over the brain. (iii) Presence of cerebrospinal fluid both outside and inside the brain to absorbs shocks.
(c) Cerebellum.
3. Two examples of plant movement are shown
(a) State the stimulus which is common for movement in both the cases
(b) Mention separately for both, whether the movement takes place away or at the point where stimulus is received.
(c) State one reason for movement in each case.
Ans. (a) Stimulus. Touch
(b) In sensitive Plant, the leave shows movement away from place of contact, at the bases of pinnules, pinnae and petiole. In tendril the movement takes place in the region of contact.
(c) In sensitive Plant movement occurs due to loss of water or turgidity by certain cells. In tendril it is due to auxin induced greater growth of cells on the side not in contact with object.
4. How does the plant shoots bends when the plant is placed in a room having only one open window? Explain briefly.
Ans. The plant will be receiving light from one side. The unidirectional light causes positive phototrophic response from the shoot. More auxin is formed on the shaded side of the shoot apex. As a result more growth occurs on the shaded side than the illuminated side. This results in bending of the shoot towards the direction of light.
5. Give an example of a plant hormone that promotes growth ?
Ans. Indole 3-acetic acid or IAA (auxin).
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