Tiêu đề 2 Control and Coordination.docx ✅

Biology Control and Coordination Some Activity Based Questions Q1. How is shoot able to bend towards the source of light? Ans. Auxin formed apically diffuses downwards to reach zone of elongation. More of it passes on the darker side than the illuminated side. Therefore, darker side grows more causing the stem to bend towards the source of light. Q2. Which one has a chemo tactic effect on pallen tube? Ans. Boron containing nutrient Q3. Why does even favourite food appear tasteless when you have bad cold? Ans. Most of taste is smell or flavor. Q4. How does horizontally kept potted plant show upward bending of shoot and downward bending of root? Ans. More auxin accumulates on the lower side of the stem and the root due to horizontal orientation. More auxin stimulates growth on the lower side of the stem. As a result stem bends upwardly. Higher concentration of auxin is inhibitory to growth of lower side of root. The upper side of the root grows more and causes the root to bend downwardly. H.O.T.S. Questions Q1. Identify and label the parts shown as A and B in the accompanying figure. Ans. Dorsal view of thyroid and parathyroid’s
A – Thyroid, B – Parathyroid Q2. How does pancreas control glucose level of blood? Ans. Pancreas produces two hormones (i) Insulin from B – cells of islets of Langerhans and (ii) Glucagon from A – cells of islets of langerhans. Insulin is produces when glucose level of blood rises. Insulin helps the cells to withdraw glucose from blood. It also converts glucose into glycogen in liver and muscles. Glucagon is secreted when glucose level of blood falls. It mobilizes reserve food like glycogen into glucose. Q3. What is dormin? Ans. Dormin is the other name of plant hormone abscisic acid. The hormone induces dormancy in buds and seeds. So it has been called dormin. Q4. What type of plant movement is seen in the diagram of coiling of tendril? Ans. Thigmotropism or curvature movement that occursin response to contant. Less auxin is present in the region of contact. The free side having more auxin shows more growth. This causes the tendril to coil over support. Q5. What are the hormones involved in providing milk to the suckling infant? Ans. 1. Prolactin (Maternity Hormone): Production of milk. 2. Oxytocin: Ejection of milk Q6. What is pregnancy hormone? Why is it known so? support Coiling of Tendril
Ans. Progesterone is called pregnancy hormone. It helps in maintaining pregnancy by nonformation of new ova, promoting thickening and secretory activity of uterine wall attachment of embryo to the uterine wall. C.B.S.E. Sample paper - 2008 Q1. A particular hormone requires iodine for its synthesis. Name the endocrine gland which secretes this hormone and state its location in the human body. Ans. Iodine containing hormone thyroxine is synthesized by endocrine gland called thyroid. Thyroid is wrapped over trachea just below the larynx. Q2. The given set up tests the response of different parts of the plant towards gravity. Use scientific terms for the conclusions. Ans. (i) Stem bends upwardly – Negative geotropism. (ii) Root bends downwardly – Positive geotropism. Q3. Which organ secretes a hormone when blood sugar rises? Name a digestive enzyme released by this organ. Ans. Pancreas: it secretes hormone insulin when blood sugar rises. Enzyme: Trypsin
Q4. (i) Label the two parts indicated by question marks and labeled 1 and 2 in the above diagram. (ii) Suggest a suitable caption or heading for the above diagram. Ans. (i) 1· Spinal cord 2· Effector (muscle in arm) (ii) Reflex Arc. Q5. Label parts 1 – 6 in the given figure of the brain. Ans. 1. Cerebrum