biology questions paper of class 12, Assignments of Biology

Download biology questions paper of class 12 and more Assignments Biology in PDF only on Docsity! Page 1 of 9 Sample Question Paper 2020-21 Class XII Biology (044) Theory Time: 3 Hours Maximum Marks: 70 General Instructions: (i) All questions are compulsory. (ii) The question paper has four sections: Section A, Section B, Section C and Section D. There are 33 questions in the question paper. (iii) Section–A has 14 questions of 1 mark each and 02 case-based questions. Section–B has 9 questions of 2 marks each. Section–C has 5 questions of 3 marks each and Section–D has 3 questions of 5 marks each. (iv) There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions. (v) Wherever necessary, neat and properly labeled diagrams should be drawn. SECTION A Questions Marks 1. Why does endosperm development precede embryo development? 1 2. How many meiotic divisions are required to produce 76 seeds in a Guava fruit? 1 3. How does pollination take place in water hyacinth and water lily? 1 4. Name the glands that contribute to human seminal plasma. 1 5. A snapdragon plant with violet flowers was crossed with another such plant with white flowers. The F1 progeny obtained had pink flowers. Explain, in brief, the inheritance pattern seen in offsprings of F1 generation? 1 6. Differentiate between aneuploidy and polyploidy. 1 7. Predict the effect if, the codon UAU coding for an amino acid at the 25th position of a polypeptide of 50 amino acids, is mutated to UAA. 1 8. Differentiate between pro-insulin and mature insulin. 1 9. Name the commonly used vector for cloning genes into higher organisms. 1 10. Which of the three forests- Temperate, Mangroves and Tropical Evergreen is more vulnerable to invasion by outside animals and plants? 1 Page 2 of 9 11. Assertion: Primary transcripts in eukaryotes are nonfunctional. Reason: Methyl guanosine triphosphate is attached to 5’ – end of hnRNA. 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. OR Assertion: An organism with lethal mutation may not even develop beyond the zygote stage. Reason: All types of gene mutations are lethal. a. Both assertion and reason are true, and the reason is the correct explanation of the assertion. b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion. c. Assertion is true but reason is false. d. Both assertion and reason are false 1 12. Assertion: E. coli having pBR322 with DNA insert at BamHI site cannot grow in medium containing tetracycline. Reason: Recognition site for Bam HI is present in tetR region of pBR322. a. Both assertion and reason are true, and the reason is the correct explanation of the assertion. b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion. c. Assertion is true but reason is false. d. Both assertion and reason are false 1 13. Assertion: A community with more species is more stable than that with less species. Reason: More the number of species, lesser the variation in the total biomass production year after year. a. Both assertion and reason are true, and the reason is the correct explanation of the assertion. b. Both assertion and reason are true, but the reason is not the correct explanation of the assertion. c. Assertion is true but reason is false. d. Both assertion and reason are false 1 Page 5 of 9 i. Sickle cell anemia is a/ an ______________________ disease. a. X linked b. autosomal dominant c. autosomal recessive d. Y linked ii. If both parents have sickle cell trait, then there is _______________of the child having sickle cell anemia. a. 25 % risk b. 50 % risk c. 75% risk d. No risk iii. If both parents have sickle cell trait, then there is _______________of the child having sickle cell trait. a. 25 % risk b. 50 % risk c. 75% risk d. No risk iv. If one parent has sickle cell anemia and the other has sickle cell trait, there is __________that their children will have sickle cell anemia and ___________will have sickle cell trait. a. 25 % risk, 75% risk b. 50 % risk, 50% risk c. 75% risk, 25% risk d. No risk v. The following statements are drawn as conclusions from the above data (Kenya). I. Patients with SCD (Sickle Cell Disease) are less likely to be infected with malaria. Page 6 of 9 II. Patients with SCD (Sickle Cell Disease) are more likely to be infected with malaria. III. Over the years the percentage of people infected with malaria has been decreasing. IV. Year 2000 saw the largest percentage difference between malaria patients with and without SCD. Choose from below the correct alternative. a. only I is true b. I and IV are true c. III and II are true d. I and III are true SECTION – B 17. State the composition and principle of oral pills as a contraceptive measure taking the example of Saheli. 2 18. Karyotype of a child shows trisomy of chromosome number 21. Identify the disorder and state the symptoms which are likely to be exhibited in this case. 2 19. Explain four advantages of mycorrhizal association to plants. 2 20. Explain the method to increase the competency of the bacterial cell membrane to take up recombinant DNA? OR What are bioreactors? How are large volumes of cultures maintained and processed in them? 2 21. Explain the role of enzymes in the extraction of DNA from Rhizopus in its purest form. 2 22. What are sticky ends? State their significance in recombination DNA technology. OR Explain the procedure by which PCR aids in early detection of cancer. 2 23. Explain how advanced ex-situ conservation techniques assist in preserving threatened species of plants and animals. 2 24. Define interference competition. Give one example that supports competitive exclusion occurring in nature. 2 25. The Tropical regions are likely to have more biological diversity than the Temperate ones. Give two reasons to justify the statement. 2 Page 7 of 9 SECTION – C 26. A fully developed foetus initiates its delivery from the mother’s womb. Justify the statement. 3 27. How would you find out the genotype of a pea plant with violet flowers? Explain with the help of Punnets’ square showing crosses. 3 28. Define flocs and state their importance in biological treatment of waste water. 3 29. A farmer noticed that nematode infection in tobacco plants has resulted in the reduction in the yield. Suggest a strategy which provides cellular defense for providing resistance to this pest. Explain the technique. 3 30. The graph given below represents three categories of organismic responses - L, M and N to cope with stressful conditions. Identify the categories L and M. Given below are examples of some of the activities performed by animals. Categorise these activities into the appropriate kind of the organismic response (L, M or N) as shown in the graph with reasons. i. In summers we sweat profusely. ii. Sometimes desert lizards bask in the sun and sometimes they move into shade. OR Give reasons for the following: a. Very small animals are rarely found in polar regions. b. Mammals from colder climate generally have shorter ear and limbs. c. Initially we feel nausea and fatigue when we reach a high altitude such as Rohtang Pass and then, gradually, we feel normal. 3