Text-book Questions
Page no. 119
Q1. What is the difference between a reflex action and walking?
Answer: The reflex action is controlled by the spinal cord part of the brain but walking is a deliberate action by the brain. Reflex action involves very little Amy, but in jogging it takes a long time for the information to reach the muscles.
Q2. What happens at the synapse between two neurons?
Answer: Synapse is the small gap between two nerve cells. The nerve impulse coming in the form of electrical waves secretes a chemical which comes in the gap of the empty space, similarly these chemicals reach the next nerve cell by crossing the synapse.
Q3. Which part of the brain maintains posture and equilibrium of the body?
Answer: Cerebellum of the posterior brain.
Q4. How do we detect the smell of an agarbatti (incense stick)?
Answer: There are some centers in the brain for receiving information in different parts. which are present in the forebrain. There is a wall lobe for smell.
Q5. What is the role of the brain in reflex action?
Answer: Reflex action is not under the control of brain. Secreted reflex actions are controlled by the spinal cord. The brain collects information about the action that takes place in the reflex action.
Page no. 122
Q1. What are plant hormones?
Answer: Plants secrete some important chemicals from their different parts which control the growth and other activities of plants, they are called plant hormones
Q2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Answer: The movement of leaves of a mimosa plant is different from the movement of shoots towards light as the movement of light and shoots is a trajectory that is controlled by the oxycin hormone. But touching the leaves of the mimosa plant causes the spreading shrinkage which is not controlled by light.
Q3. Give an example of a plant hormone that promotes growth.
Answer: Occin Hormone.
Q4. How do auxins promote the growth of a tendril around a support?
Answer: Pratan is a sensitive plant, as soon as it comes in contact with any of its shares, water and auxin move in the opposite direction. In this way the cells become elongated and ductile and the protuberance is twisted and wrapped around the base.
Q5. Design an experiment to demonstrate hydrotropism.
Answer: Experiment to show hydrotropism - Take a plant and grow it in a pot, its soil should be wet from one side and dry from other side. After testing it after a few days, we will find that the roots of the plant move towards the aquatic soil, from this design we find that there is a positive hydrotropism in the roots.
Page no. 125
Q1. How does chemical coordination take place in animals?
Answer: Special glands secrete certain hormones in animals. These hormones do chemical coordination.
Q2. Why is the use of iodised salt advisable?
Answer: Use of iodized salt is recommended because thyroid controls the digestion of carbohydrates, fats and proteins in the body. This gland secretes a hormone called thyroxine. Iodine is required for this gland. Iodine deficiency causes goiter disease
Q3. How does our body respond when adrenaline is secreted into the blood?
Answer: Due to the release of adrenaline in the blood, the heart beats faster, our muscles increase and the respiratory rate also increases.
Q4. Why are some patients of diabetes treated by giving injections of insulin?
Answer: Insulin is needed to control the increased sugar in the blood. This hormone is controlled by it and it is secreted by the pancreatic gland. Its secretion is less in diabetic patients, so the injection of insulin controls the sugar in the blood.
