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DELHI PUBLIC SCHOOL NEWTOWN SESSION 2018-2019 PREBOARD EXAMINATION CLASS: X SUBJECT: BIOLOGY [SET: B] FULL MARKS: 80 TIME: 2 HOURS Answers to this paper must be written on the paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the question paper. The time given at the head of this paper is the time allowed for writing the answers. Attempt all questions from Section I and any four questions from Section II. The intended marks for questions or parts of questions are given in brackets [ ]. This question paper consists of seven printed pages. SECTION I (40 Marks) Attempt all questions from this Section QUESTION 1 (a) Name the following: [5] i) A solution whose concentration is greater than that of the cell sap. ii) The surgical method of contraception in human female. iii) The enzyme which facilitates entry of sperm into the egg. iv) A growth inhibiting hormone in plants. v) The first human ancestor who walked upright. (b) Correct the following incorrect statements by changing the underlined word only:[5] i) Prolactin is the female hormone responsible for "milk-let-down" response. ii) Metaphase is the phase of mitotic cell division in which the sister chromatids of each chromosome separate. iii) Surgical method of sterilization in a woman involves cutting and tying of Ureter. iv) Marine fish when placed in tap water bursts because of Plasmolysis. v) Diencephalon links the endocrine and the nervous system via the Pituitary gland. (c) Give the technical terms for the following: [5] i) The pressure exerted by cell contents on a plant cell. ii) Addition of phosphate and conversion of low grade energy ADP into high potential chemical energy ATP in presence of light. iii) The ability of the human eye to focus/change the focal length so as to see objects at different distances. iv) A sudden change in one or more genes or in the number or in the structure of B/1
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