• Comprehension-based Questions:

Question 1. What does it mean by vernalization?

Answer: The acceleration of flowering of plants by applying chilling on them is called vernalization.

Flowering is prolonged if the wheat of winter is cultivated in summer. If 2° – 5° temperature is applied on the seeds after sowing, the normal flowering occurs in them. This process is known as vernalization.

Question 2. What is hormone?

Answer: The secretions produced by the ductless glands or endocrine glands are known as hormone.

Hormones are carried by blood current and reach to the specific cells, influence the biochemical function within the cells and regulate the biological process.

Question 3. Why does reflex action occur?

Answer: Reflex action means a sudden response or automatic reaction.

For example, at the time of pricking, the dendrites of the sensory neuron, accept the stimulus. This stimulus transmits from the finger to the grey matter of the spinal cord through the axon of the neuron. Impulse transmits between the axon of the sensory nerve and dendrite of the motor or efferent nerve through synapse. Then the impulse results in muscle contraction.

Question 4. How can we hit the mosquito so suddenly?

Answer: We can hit the mosquito so suddenly by our reflex action.

Reflex action is an involuntary and instantaneous movement in response to a stimulus. When mosquito bites, our reflex action helps us to locate it with nerve sensation and activates the muscle to kill it.

Question 5. Write down the function of pituitary gland?

Answer: The pituitary gland or hypophysis is situated beneath the brain. It is the main hormone producing gland in the human body, because it secretes several hormones.

Some of these have an influence on other endocrine glands. It is the smallest in size, but it is a very important endocrine gland. It secretes thyroid stimulating hormones, such as: gonadotropin, thyrotropin, prolactin, somatotropin etc.

Question 6. What do you mean by salivary gland?

Answer: The salivary glands produce saliva, which keeps the mouth and other parts of the digestive system moist.

It also helps break down carbohydrates, soften foods for easy swallowing and prevents bacterial infection with the help of lysozyme.

Question 7. Explain the cause of high blood pressure.

Answer: There is a strong probability of high blood pressure or hypertension for those whose parents have got this disease. Besides this those, who suffer from tension or smoking habit, have the probability of hypertension. An increase in body weight, intake of excessive salt and fatty diet and history of diabetes and cholesterol of family members are the causes of this disease.

Question 8. Why florigen is called postulated hormone?

Answer: Postulated hormones mainly help the activities related to the development of flowers and reproductive organs. Florigen is formed in the leaves and translocated to the base of the petiole, transforming the vegetative buds into floral buds. So, it is found that florigen helps a plant in its flowering and acts as a postulated hormone.

Question 9. Describe gaseous phytohormone.

Answer: Ethylene is the gaseous phytohormone.

It helps the fruit to be ripened. This hormone is also found in fruits, flowers, seeds, leaves, and roots. Ethylene breaks the dormancy in seeds and buds and helps seedlings to grow much in length. Ethylene accelerates the shedding of leaf, flower, and fruit.

Question 10. What do you mean by autonomic nervous system?

Answer: The part of the nervous system responsible for the control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes is called the automatic nervous system.

Question 11. What is meant by phototropic motion?

Answer: Phototropic motion is an oblique motion of plants.

Motion of the stem and branches of plants occur towards the sun or its light and the motion of root is opposite. Motion of the stem towards the sun or its light is called positive phototropic and the motion of root opposite to the sun or its light is called negative phototropic motion.