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ISC Class XI Prelims 2024 : Biology (Delhi Public School (DPS), Newtown, Kolkata)

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Snigdha Patra
Delhi Public School (DPS), Newtown, Kolkata

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DELHI PUBLIC SCHOOL NEWTOWN SESSION 2024-2025 FINAL EXAMINATION CLASS: XI SUBJECT: BIOLOGY [SET -A] FULL MARKS: 70 TIME: 3 HOURS [Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time]. This paper is divided into four sections A, B, C and D. Answer all questions. Section - A consists of one question having sub-parts of one mark each. Section-B consists of seven questions of two marks each Section-C consists of seven questions of three marks each, and Section-D consists of three questions of five marks each. Internal choices have been provided in one question each in Section B, Section C and Section D. The intended marks for questions or parts of questions are given in brackets []. The paper consists of 6[six] printed pages. SECTION A 20 MARKS Question 1 Answer the following questions briefly: i. Ramu s grandmother was in her seventies, when she started experiencing stiffness and inflammation in her joints. What is this condition called? State one reason for the appearance of these symptoms. [1] ii. A parenchymatous cell has 20 units of DNA. It starts to divide mitotically. How many units of DNA would it have: (a) during late prophase (b) during very late telophase? [1] iii. A farmer grows cucumber plants in his field. He wants to increase the number of female flowers in them. Which plant growth regulator you would suggest him to apply to achieve this? [1] iv. A patient with advanced renal failure is waiting for a suitable kidney donor for transplantation operation. His blood urea level is high and he developing some of the signs of uraemia. What method can you adopt to keep this patient alive until a suitable donor is found? [1] v. In a road accident, a person receives a severe blow to the head but appears to be all right. Over time, however, he develops loss of appetite, thirst and sexual capacity, but no loss in sensory or motor function. Which part of the brain do you think has been damaged? [1] A/1 vi. Reema s mother told her not to talk or laugh while having food or water. Reema found out that the epiglottis plays an important role during swallowing. How does the epiglottis prevent food and liquids from entering the respiratory tract? [1] vii. Mr. Ashok was suffering from an acute pain in his chest. When he visited a doctor, he learnt that his acute chest pain was due to failure of oxygen supply to heart muscles. What is this pain called? Which condition of the heart does it indicate? [1] viii. Vicky was suffering from acute anemia since a long time. The doctor advised him to take a course of Erythropoietin injections. Why did the doctor suggest this? [1] ix. If carbon dioxide concentration in the blood increases, the rate of breathing will: (a) Increase (b) Decrease (c) Stop (d) Remain unaffected [1] x. When the action potential begins, sodium gates open, allowing them to cross the membrane. Now the polarity changes to [1] (a) Negative outside and positive inside (b) Positive outside and negative inside (c) There is no difference in charge between outside and inside (d) Negative inside and negative outside xi. Assertion: Muscle and nerve cells greatly differ in structure and function. Reason: They contain different genetic information. [1] (a) Both assertion and reason are true, and reason is the correct explanation of assertion. (b) Both assertion and reason are true, but reason is not the correct explanation of assertion. (c) Assertion is true but reason is false. (d) Both assertion and reason are false. xii. Assertion: When cytokinin is applied to plants, it induces senescence. Reason: Cytokinin promotes the breakdown of proteins, chlorophyll and nucleic acids. [1] (a) Both assertion and reason are true, and reason is the correct explanation of assertion. (b) Both assertion and reason are true, but reason is not the correct explanation of assertion. (c) Assertion is true but reason is false. (d) Both assertion and reason are false. A/2 xiii. Hari was studying plant tissues, and he came across the following picture. Help him to identify the plant tissue. [1] xiv. You have been given two plasma samples, one from an artery, and one from a vein in the arm. Which sample do you think will contain more HCO3- ions in it? [1] xv. Raman had gone to visit the anatomy museum, and he came across a joint which he couldn t identify. Help him to identify the type of joint marked as X . Also state one location where it is found. [1] X xvi. Give a term for the following: [2] (a) The transformation of simple, meristematic cells into a distinct permanent form with a specialized function. (b) The natural anticoagulant found in blood. xvii. Rita was watching a program on television, and she saw that owls can see better at night. However, she couldn t understand why. Help her to understand this concept. [1] xviii. Give a reason for each of the following: [2] (a) Removal of tonsils may prove to be costly for a human being. (b) People working in asbestos industries are advised to use protective gears and clothing. SECTION B [14 MARKS] Question 2 (i) (ii) [2] Draw a neat labelled diagram to show the internal structure of a Chloroplast. OR Draw a neat labelled diagram to show the ultrastructure of a Ribosome. A/3 Question 3 [2] Raman was studying the Circulatory system in humans. He was surprised to know that although both are blood vessels, arteries and veins have significant differences between them. How are arteries structurally different from veins? Question 4 [2] Daniel s mother is a patient of diabetes mellitus, and takes insulin injections. One day, while walking back home from the market, she suddenly had a blackout and fainted. After this incident, the doctor asked her to keep a few toffees / sweets in her bag at all times. Why did she faint? Why do you think the doctor asked her to carry toffees? Question 5 [2] Proteins are large biomolecules formed by the binding of multiple amino acids. They play a significant role in the functioning of all living organisms. Mention four important biological functions of proteins. Question 6 [2] Given below is a diagram showing a stage of Mitosis. Observe the diagram and answer the questions that follow: (a) Identify the stage shown in the above diagram. (b) State an important identifying feature of this stage. Question 7 [2] Nepenthes (commonly called as pitcher plant) is an insectivorous plant that usually grows in marsh lands. Which part of the leaf is modified to form a pitcher ? How does this modification help the plant to obtain food even though it can photosynthesize like any other green plant? Question 8 [2] Anisha was boiling a pan of milk in the kitchen. She wanted to make some cottage cheese. Upon reading the recipe, she found that some lemon juice had to added to the milk. As soon as Anisha added the lemon juice, she was amazed to see the milk solids separate out from the water inside the pan. Identify and define the phenomena observed by Anisha. A/4 SECTION C [21 MARKS] Question 9 [3] Seed dormancy is a condition in which the rate of metabolic activities of embryo is extremely low and process of growth and development is completely suspended. Seed dormancy can be caused by several factors like impermeable and hard seed coat, immature embryo and presence of chemical inhibitors. State and briefly explain three methods of breaking seed dormancy. Question 10 (i) (ii) [3] Sameer was studying Locomotion, and he came across an image of Sliding Filament Theory of muscle contraction. Based on the image given below, explain the Electrical and Biochemical events that occur during muscle contraction. OR Differentiate between Sympathetic and Parasympathetic Nervous System. Question 11 [3] Rajesh was a chain smoker for many years. In his mid-fifties, when he went for a yearly checkup, he was diagnosed with Emphysema. What changes occur in the alveoli in this disease? Mention two methods for prevention and cure of Emphysema. Question 12 [3] Tanay had observed excessive deposition of fat over his face, back of the neck and abdomen. He also noticed an abnormal growth in his body hair. Based on Tanay s symptoms, answer the following questions: (a) Which disease/syndrome was Tanay suffering from? (b) Why is this disease/syndrome caused in humans? (c) How are the testes affected in this condition? Question 13 [3] Seema learnt in her Biology class that blood travels twice through the heart in the human body. However, she couldn t clearly understand the concept of Double Circulation. Explain Double Circulation in humans. Support your answer with a neat flow diagram. A/5 Question 14 [3] The ultimate source of light for photosynthesis is solar radiation. Light varies in quality, intensity and duration, and all the three have direct influence on photosynthesis. Explain how light intensity affects photosynthesis. Support your answer with a graph showing the effect of light intensity affects the rate of photosynthesis. Question 15 [3] Gita was studying the anatomy of flowering plants, and was intrigued to read about the difference in structures of dicot and monocot stem. Help her answer the following questions about the anatomy of dicot stem: (a) Where exactly are the cambial cells located in the vascular bundles? (b) What is the name given to such a bundle? (c) How are the xylem vessels arranged? (d) What type of cells constitute the pith? SECTION D [15 MARKS] Question 16 (i) (ii) [5] Rajesh was walking barefoot in his house. Suddenly, he stepped on something sharp and jumped up. To his dismay, he realized that he had stepped on a sharp nail, and was now bleeding profusely. (a) Identify and define the phenomena which made Rajesh jump up. (b) Draw a neat flowchart to show the pathway of the phenomena named by you in (a) above. (c) Why is Presbyopia caused? OR C4 cycle, also referred to as the Hatch-Slack pathway, is found in tropical and subtropical grasses like crabgrass, maize and sugarcane. It comprises of four phases: Initial fixation of CO2, Transport, Final fixation of CO2, and Regeneration. With the help of a neat flowchart and suitable explanations, show the steps of Hatch-Slack pathway. Question 17 [5] Glycolysis is the partial oxidation of glucose into two molecules of pyruvic acid through a series of enzyme mediated reactions releasing some energy. In anaerobic organisms, it is the only process of respiration. With the help of a flowchart, show the steps of Glycolysis. Question 18 [5] Sania was watching a program on Excretory system, and was amazed to know that hormones play a significant role in regulating the volume of urine in humans. Explain the hormonal regulation of urine volume. A/6

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