1.(a) design an experiment to demonstrate positive and negative geotropism.
(b) give reasons for the following -
(1) use of iodised salt is adviced
(2) salivation is considered an involuntary action
(3) the brain is surrounded by fluid.
1. Take a potted plant and place it horizontally so that root and shoot are parallel to the ground. Now observe the position
of growing stem and roots after few days. You will observe that stem of the plant bends upwards, that is, away from the earth (negative geotropism) while roots of the plant bends downwards, that is, towards the earth (positive geotropism). Hence this experiment confirms that shoots show negative geotropism and roots show positive geotropism.
2. (a) Iodide salt contains iodine which is required by thyroid gland for the manufacture of thyroid hormones. Thyroid hormones regulate the metabolic rate of the body, stimulate protein synthesis, regulate development of mental faculties and maintain body temperature. Hence, it s advisable to consume iodised salt.
(b) Salivation is considered an involuntary action because it cannot be controlled by our will.
(c) Brain is surrounded by cerebrospinal fluid which protects the delicate and spinal cord by providing shock absorbing medium. Cerebrospinal fluid also carries harmful metabolic wastes, drugs and other substances from the brain to the blood.
of growing stem and roots after few days. You will observe that stem of the plant bends upwards, that is, away from the earth (negative geotropism) while roots of the plant bends downwards, that is, towards the earth (positive geotropism). Hence this experiment confirms that shoots show negative geotropism and roots show positive geotropism.
2. (a) Iodide salt contains iodine which is required by thyroid gland for the manufacture of thyroid hormones. Thyroid hormones regulate the metabolic rate of the body, stimulate protein synthesis, regulate development of mental faculties and maintain body temperature. Hence, it s advisable to consume iodised salt.
(b) Salivation is considered an involuntary action because it cannot be controlled by our will.
(c) Brain is surrounded by cerebrospinal fluid which protects the delicate and spinal cord by providing shock absorbing medium. Cerebrospinal fluid also carries harmful metabolic wastes, drugs and other substances from the brain to the blood.