From last 2 years, CBSE has changed the pattern of Biology question papers. In the new pattern, students are not required to write the big and long paragraphs but very specific and to the point answers.
This CBSE class 12 Biology practice paper will provide you the similar kind of pattern as the cbse board has followed in the previous years . In this paper we are providing the questions from complete biology syllabus. Do practice the questions and check your preparation for the cbse board exam biology paper 2017.
General Instructions for the practice paper are as follows:
Time: 3 hrs
Max Marks: 70
1. All the questions are compulsory.
2. The question paper consists of four sections A, B, C and D. Section A has 8 questions of 1 mark each. Section B has 10 questions of 2 marks each. Section C has 9 questions of 3 marks each, Whereas Section D has 3 questions of 5 marks each.
3. There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weight age. A student has to perform only one of the alternatives in such questions.
4. Wherever necessary, the diagrams drawn should be neat and properly labeled.
1: Offspring of vegetative reproduction is called as clone. Why?
2: Define the term "fitness" with respect to Darwin's theory of natural selection.
3: Name the technique used to improve the frequency of successful production of hybrids.
4: Desired increases in yield with existing varieties are not possible using conventional breeding. Why?
5: Mention one of the Euro II norms laid out to cut down vehicular pollution in Indian cities.
6: What are A and B in the transcription unit represented below?
7: Meiosis produces haploid gametes in diploid parents. Does meiosis occur in the haploid organisms?
8: Define one features of genetic code. Give example.
1. Mention the steps used in production of high yielding sugar cane variety with thick stem and high sugar content through conventional plant breeding.
2. What is corpus luteum? How does it function as an endocrine gland?
3. Name the kinds of organisms which constitute the pioneer community of xerarch and hydrarch succession respectively.
4. What kind of growth status of human population these pyramids show? Identify and name them.
5. What are genetically modified organisms? Name two factors on which their behavior depends.
6. Name any four alcoholic beverages.
7. What are induced mutations? Give one example each of physical and chemical mutagens.
8. What is contact inhibition? How does this phenomenon operate in cancer cells?
1. (a) Angiospermic embryo sac is 8 nucleate and 7 celled structure. Justify
(b) Mention the function of synergids in an embryo sac.
(c) What happens to the central cell after double fertilization?
(a) How do natural methods serve as contraceptive techniques?
(b) Name two natural methods of contraception.
(c) How does lactational amenorrhea prevent conception?
2. Explain the results of monohybrid cross on the basis of law of dominance and the law of segregation.
3. How did complementary base pairing feature of polynucleotide chain explain the genetic implication of DNA structure?
4. (a) Mention the theory of evolution as proposed by Oparin and Haldane.
(b) What were the supposed conditions of primitive earth during abiogenesis?
(c) What was the composition of reaction mixture of Oparin and Haldane experiment? Name the obtained products.
5. (a) Name the species of Plasmodium which is responsible for most serious type of malaria.
(b) Name the factor responsible for malaria fever with chills.
(c) How does female Anopheles mosquito serve as the vector for malaria?
6. What is the difference between out-breeding and out-crossing? Choose the best breeding method for cattle with low milk production.
7. What makes the bottled fruit juices clearer as compared to those made at home? Name the bioactive molecules responsible for it.
8. (a) What are the tools for rDNA technology? Give two examples. State the function of each.
(b) Mention the steps required to produce a genetically modified organism.
9. Briefly explain the features required to facilitate cloning into a vector.
10. (a) What is RNA interference? Mention its role in production of pest resistant plants.
(b) Briefly explain how genetically modified plants are better than the conventional crops?
11. (a) Name the key elements that lead to variation in the physical and chemical conditions of different habitats.
12. How does temperature affect the life of organisms on earth? Why it is considered the most important abiotic factor?
13. (a) What is the difference between gross and net primary productivity?
(b) Why oceans are considered low productive ecosystems? Justify your answer.
1. Prepare a dihybrid cross between homozygous tall plant bearing round seeds and a dwarf plant with wrinkled seeds through two generations using Punnet square. Give the dihybrid phenotypic ratio.
Study the given pedigree chart and answer the questions that follow:
(i) Is the trait recessive or dominant?
(ii) Is the trait sex linked or autosomal?
(iii) Give the genotypes of the parents in generation I and of their third and first grand child in generation III.
(iv) List out any two uses of pedigree chart.
2. What are the two groups of cells that work for specific immunity? Explain four unique features of specific immunity.
Study the given aquatic food chain and answer the questions that follow:
Water (DDT 0.003ppm) -----> Zooplankton (DDT 0.04 ppm) -------> Small fish (DDT 0.5 ppm) -----> Large Fish (DDT 2ppm) ----------> Fish eating Birds (DDT 5 ppm)
(i) Explain why there is a continuous increase in DDT content in different trophic levels of the chain?
(ii) Name the phenomenon responsible for the increase in DDT content.
(iii) How does this phenomenon disturbs the metabolism of birds?
3: (a) How do regulators and conformers differ from each other with respect to their response to changes in abiotic factors?
(b) Some organisms show behavioural responses to cope with variations in their environment. Justify with example.
(a) Alien species invasions and habitat fragmentation causes loss of biodiversity. How?
(b) Outline the concept behind working of electrostatic precipitator as remover of particulate matter from exhaust.
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