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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 chromosomes. v) The kind of ratio obtained in the progeny in F2 generation, by crossing, for two different traits of a single character. (d) Given below are six sets, with four terms each. In each set, one term is odd and cannot be grouped under the category to which the other three belong. Identify the odd one in each set and name the category to which the remaining three belong. The first one has been done for you as an example. [5] Set Example: i. Retina, Cochlea, Ciliary muscles, Cornea ii. Cuticle, Lenticels, Hydathodes, Stomata iii. Beard, Voice cracking in males, Development of breast, Ovaries iv. Thyroid, Salivary, Pituitary, Adrenal Category Part of human eye Odd one cochlea v. Dura mater, Grey mater, Pia mater, Arachnoid vi. Cataract, Myopia, Lens, Night-blindness (e) Given below is a diagram of an experimental setup. Answer the questions after observing the diagram carefully: [5] i) ii) iii) iv) v) Define the process being studied. Why is the pot covered with a rubber sheath? Mention two ways by which the process is beneficial to the plant. State two ways by which leaves can check this process. Mention one criteria of the plant which needs to be fulfilled for the above experiment. B/2 (f) Choose the correct option from the alternatives given below: [5] i) A plant is kept in a dark cupboard for 48 hours before conducting any experiment on photosynthesis to: a. Remove chlorophyll from the leaves. b. Remove starch from the plant. c. Ensure that no photosynthesis occurs. d. Ensure that no respiration occurs. ii) The mineral essential for clotting of blood is: a. Magnesium b. Zinc c. Molybdenum d. Calcium iii) Ovulation occurs: a. at the beginning of menstrual cycle b. in the mid of the menstrual cycle c. at the end of the menstrual cycle d. during any time of the menstrual cycle. iv) Synthesis (S) phase in the cell cycle is so called for the synthesis of: a. RNA b. RNA and DNA c. DNA d. RNA and proteins v) Birth rate is the number of live births: a. Per 1000 people per year. b. Per 100 people per year. c. Per 1000 people per decade. d. Per 10 people per year. (g) Complete the following table: [5] Plant hormone Site of synthesis One important function Auxin i. Promote cell elongation Gibberellins Cytokinins ii. iii. Delay senescence Stimulate cell division Ethylene Senescent leaves and flowers iv. Abscisic acid v. Accelerates senescence (h) Explain the following terms: i) Homologous Chromosomes ii) Apical Dominance iii) Menarche iv) Fraternal Twins v) Theory of Use and Disuse [5] B/3 SECTION II (40 Marks) Attempt any fourquestions from this section QUESTION 2 A. Given below are the diagrams of certain structures in plants in certain conditions. [ +2 +2=5] i. ii. iii. Name the structure shown. Label the parts numbered 1 to 5 in A. What are the most apparent differences between A and B in the structures shown? Account for these differences. B. Give reasons for the following: i. On a bright sunny day, the leaves of certain plants roll up. ii. Gibberellins are plant hormones which are widely used in horticulture. iii. Pancreas is a heterocrine gland. iv. A plant cell when kept in a hypertonic solution for about 30 minutes turns flaccid. v. Only the veins and not the arteries are provided with valves. QUESTION 3 A. An experiment was set up as shown in the diagram below: [1+1+1+2=5] i. What is the aim of this experiment? ii. Why was a part of the leaf covered with black paper? B/4 [5] iii. What test would you do on the leaf after a few hours? iv. Explain the result obtained from the above experiment. B.Given below are certain functional activities of specific structures in the body of living organisms. Name the structure responsible for the same. [5] i. Acts as a carrier of hereditary units. ii. Controls the activities of the internal organs. iii. Performs ultrafiltration. iv. Holds the heart valves in position and prevents their up tilting. v. Engulf bacteria to provide immunity. QUESTION 4 A. The diagram given below shows the internal structure of human heart. Observe the diagram carefully and answer the questions that follow: [3+1+1] A B F E C D i. ii. iii. Label the parts A F. Name the vein which starts and ends in capillaries. By means of a flowchart explain the term "double circulation". B. Given below is an experimental setup showing a phenomenon in plants. Observe the diagram carefully and answer the questions that follow: [1+1+1+2] B/5 i. ii. iii. iv. Name the instrument shown above. Name the phenomenon demonstrated by the above experiment. Define it. What will you observe in the set up in the plant if it is kept as it is after a few days? Give a reason for your answer in (iii) above QUESTION 5 A. The diagram below represents a sectional view of the human male reproductive system. Study the diagram and answer the questions that follow: [2 +1+1+ =5] E C D A B i. ii. iii. iv. Label the parts numbered A, B, C, D and E. Why are parts A and B located outside the body? Write one important function of the part labelled C. State the name of the cell which produces testosterone. B. Match the items given in Column A with the most appropriate ones in Column B and rewrite the correct matching pairs: [5] i. ii. iii. iv. v. Column A Sympathetic nerves Inner portion of spinal cord Corpus callosum Applying brakes Rod cells a. b. c. d. e. f. g. h. Column B Joins the cerebral hemispheres Adrenaline Rhodopsin White matter Rhodopsin Grey matter Yellow spot Conditioned reflex QUESTION 6 A. Differentiate between the following pairs of terms based on the criteria given in brackets: i. Lymphocytes and Neutrophils. (structure of the nucleus) ii. ACTH and ADH (hormone secreting gland and function) iii. Aqueous humour and Vitreous humour (location) B/6 [5] iv. v. Spinal nerves and Cranial nerves (number) Myopia and Hyperopia (formation of the image with respect to retina) B. Study the figure given below and answer the questions that follow: i. ii. iii. iv. [ +2+2+ =5] Name the ancestral human as shown in the figure. Write four important characteristics of the ancestral human named by you in (i) above. Mention the height and cranial capacity of this ancestral human. Name the scientist who proposed the Theory of Natural Selection. QUESTION 7 A. Study the picture given below and answer the questions that follow: [ +1 +2+1=5] i. ii. iii. iv. Identify the type of pollution shown in the picture above. Name three sources of the pollution named by you in (i) above. Write two harmful effects of the pollution named by you in (i) above. Mention one way to minimise the type of pollution named by you in (i) above. B. With reference to Human Population Control answer the following questions: i. ii. iii. iv. v. [5] What is meant by family welfare centres? What is the symbol of family welfare in our country? Give two advantages of a small family. Expand IUD. How effective are they as contraceptives? Explain the term "Vasectomy" briefly. State any two factors responsible for population explosion in India. B/7
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