Class 10 CBSE Board Questions ( September Term-01)
Q. Mention the three main major regions of the brain and mention the function of each one of them?
Ans: (a) The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. It also controls movement.
(b) The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance.
(c )The brain stem sits beneath your cerebrum in front of your cerebellum. It connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate and blood pressure.
Q. List four plants hormones and write one function of each?
Ans: Plant hormones helps in coordinating growth and development in plants, and there by showing response to the environment. Auxins: Help in the growth of root shoot tips. Gibberellins : Help in vegetative growth Cytokinins : Promote cell division Abscisic acid: It promotes seed dormancy by inhibiting cell growth. It is involved in the opening and closing of stomata. It is also responsible for the shedding of leaves. Ethylene : It regulates fruit ripening. It is produced during the ripening of fruits.
Q. What is phototropism ? How does it occur in plants? Describe an activity to demonstrate phototropism.
Ans: The growth movements in plants in response to light as stimulus is said to be phototropism
Activity: To demonstrate phototropism in plants.
Requirements: A potted plant, Procedure: Take a potted plant and keep it in the sunlight in a horizontal position and observe the growth of roots and shoots. Observation: The shoots of the plant grow towards sunlight and roots away from sunlight Conclusion: Roots are negatively phototropic and shoots are positively phototropic
Q. Name a hormone secreted by :a) pancreas b)pituitary c)thyroid. state one function of each of the hormone.
Ans: Thyroxin (secreted by thyroid gland) The hormone called thyroxin helps in coordinated growth. It regulates carbohydrate, fat, and protein metabolism in our body. The deficiency of this hormone results in the enlargement of the thyroid gland or goitre.
Growth hormone (GH) (secreted by the pituitary gland) Growth hormone (GH) is involved in the growth and development of the human body. The secretion of this hormone should be properly maintained in the body. Over secretion of this hormone results in abnormal growth of the body known as gigantism. On the other hand, its low secretion results in dwarfism.
Insulin (secreted by pancreas) The pancreas secretes a hormone called insulin, which regulates the blood sugar level in the human body. It increases the permeability of the cell membrane for glucose and accelerates the passage of glucose into the cells from the bloodstream.
Q. What Is a Reflex Arc? Draw a flowchart showing of events which occur during sneezing Ans: A reflex arc is a nerve pathway in the body of humans and some animals that connects certain muscle groups to others, without involving the brain. olfactory receptors ---> sensory neurons -------> Brain --> motor neurons ------> effectors Nerve endings located in the nasal passage identifies the irritant entered in the nose ↓ Receptor sends the information or nerve impulse to the sneezing centre located in brain stem ↓ Brain stem in return sends instructions to the lungs or diaphragm for response ↓ Diaphragm moves abruptly, chest muscles contract in response to the instructions received ↓ Air blows out from nose and mouth instantly and rapidly ↓ Sneezing occurs in response to the irritant
Q. Which gland secretes digestive enzyme as well as hormones?
Ans: Pancreas is the gland which secretes digestive enzymes as well as hormones. It sectretes Pancreatic Juice (containing Amylase, Trypsin and Lipase) and it also secretes Insulin and Glucagon hormones essential for regulation of blood glucose levels
Q.Why is the flow of signals in a synapse from axonal end of one neuron but not the reverse?
Ans: When electrical signal reaches axon end of neuron , it releases chemical substance . This chemical diffuse towards the dendrites end of next neuron where it generate electrical impulses. Hence, Chemical signals is converted into electrical signals at the axon ends. Since these chemicals are absent at dendrites end of neuron, the electrical signals cannot be converted into chemical signals.
Q. Give a reason to explain why : (i) adrenaline helps in dealing emergency situations? (ii) secretions of growth hormone should be specific in the human body? (iii) some patients of diabetes are treated by giving injections of insulin?
Ans: (a) (i) Adrenaline helps in dealing emergency situations as it is secreted when are very energy
as emotional, when we get excited etc. This hormone gives us enormous amount of energy which helps as in responding to situations. For eg. When me are afraid or scared of a person and that person suddenly comes in front of us, we start running.
(ii) Secretion of growth hormones should be specified in human beings as if it is secreted in extensive amount, it may result in gigantism and it released quite less, then it may result in dwarfism. Therefore it should be secreted in a normal amount.
(iii) Some patients of diabetes are given injections of insulin as during diabetes a comparatively less amount of insulin is secreted which doesn’t check the sugar level in our body. So, in order to maintain the sugar level in our body, some patients are given injections of insulin.