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CBSE Class 12 Biology Last 5+1 Years’ Short Questions

Jan 18, 2017 10:50 IST

    With the final date announced for the CBSE class 12 Biology paper that is 5th April, 2017, students appearing for the exam must have geared up for the final revisions. Now it’s important for the students to utilize this mean time more cautiously by following the best strategic study plan. The best practice would be solving the previous years’question papers which will not only help you to track your performance but also to understand the exam pattern and marking trends. Moreover, it will give a clear overview of the types of questions asked in the board exam.

    Jagranjosh here brings a collection of Class 12 Biology Last 5+1 years’ Short Questions to help the students get a firm grip over the type of questions that are probably going to be asked in the upcoming board exam.

    As per the latest exam pattern CBSE Class 12 Biology paper contains two kinds of short answer type questions: Section B contains questions number 6 to 10, short-answer type I questions of 2 marks each and Section C contains questions number 11 to 22, short-answer type II questions of 3 marks each.


    1. In a dihybrid cross white eyed, yellow bodied female Drosophila crossed with red eyed, brown bodied male Drosophila produced in F2 generation 1.3 percent recombinants and 98.7 percent progeny with parental type combinations. This observation of Morgan deviated from Mendelian F2 phenotypic dihybrid ratio.  Explain, giving reasons,Morgan’s observations.

    2. How are recombinant vectors created? Why is only, one type of restriction endonuclease required for creating one recombinant vector?

    3. Bear hibernates whereas some species of zooplanktons enter diapauseto avoid stressful external conditions. How are these two ways differentfrom each other?

    4. The figure below shows the relative contribution of four greenhousegases to global warming:

    (i) Identify the gases A and C.

    (ii) Why these four gases are called the greenhouse gases?

    5. At the time of Independence, the population of India was 350 million, which exploded to over 1 billion by May 2000. List any two reasons for this rise in population and any two steps taken by the Government to check this population explosion.

    6. Explain the function of ‘reservoir’ in a nutrient cycle. List the twotypes of nutrient cycles in nature.


    Explain with the help of two examples, how the pyramid of numbersand the pyramid of biomass can look inverted.

    7. A list of three flowering plants is given below. Which ones out of them are

    (i)monoecious and (ii) bearing pistillate flowers :

    List — Date palm, Cucurbits and Pea.

    8. Name the organism from where thethermostable DNA polymerase is isolated. State its role in genetic engineering.

    9. Study the flow chart given below:

    (i) Identify the events that take place at stages (1) and (2)respectively.

    (ii)State the importance of the technology explained above.

    10. Give the scientific name of the microbes from which cyclosporin A and statin are obtained. Write one medical use of each one of these drugs.

    11. Draw a labeled diagram of the microscopic structure of a human sperm.

    12. Convergent evolution and divergent evolution are the two concepts explaining organic evolution. Explain each one with the help of an example.

    13. (a) Name a drug used (i) as an effective sedative and pain killer (ii) for helping patients to cope with mental illnesses like depression, but often misused.

    (b) How does the moderate and high dosage of cocaine affect the human body?

    14. Name the ‘inducer’ for this operon and explain its role.

    A. Identify i and p

    b. Name the inducer for this operon and explain its role.

    15. Explain the different steps involved in sewage treatment before it can be released into natural water bodies.

    16. Study the three different age pyramids for human population givenbelow and answer the questions that follow:

    (i) Write the names given to each of these age pyramids.
    (ii) Mention the one which is ideal for human population and why.

    17. Name a disorder, give the karyotype and write the symptoms a humansuffers from as a result of monosomy of the sex chromosome.

    18. Explain, giving one example, how co-extinction is one of the causes ofloss of biodiversity. List the three other causes also (without description).


    Eutrophication is the natural aging of a lake. Explain.

    19. IARI has released several varieties of crop plants that are biofortified. Give three examples of such crops and their biofortifications.

    CBSE Class 12 Physics Last 5 + 1 Years’ Short Answer Type Questions
    Get the solution for CBSE Class 12 Physics Last 5 + 1 Years Papers


    20. (a) Draw a neat labelled diagram of a nucleosome.
          (b) Mention what enables histones to acquire a positive charge.

    21. State one advantage and one disadvantage of cleistogamy.

    22. (a) Where do the signals for parturition originate from in human?
             (b) Why is it important to feed the newborn babies on colostrum?

    23. (a) A recombinant vector with a gene of interest inserted within the gene of α-galactosidase enzyme, is introduced into a bacterium. Explain the method that would help in selection of recombinant colonies from non-recombinant ones.

    (b) Why is this method or selection referred to as “insertional inactivation"?

    24. Explain brood parasitism with the help of an example.

    25. Give reasons for the following
          a) The human testis are located outside the abdominal cavity.
           b) Some organisms like honey-bees are called parthenogenetic animals.

    26. Name the plant source of ganja. How does it affect the body of the abuser?


    Name the two special types of lymphocytes in humans. How do they differ in their roles in immune response?

    27. (a) Mention the cause and the body system affected by ADA deficiency in humans.

     (b) Name the vector used for transferring ADA.DNA into the recipient     cells in humans. Name the recipient cells.

    28. How did Ahmed Khan, plastic sacks manufacturer from Bangalore, solve the ever-increasing problem of accumulating plastic waste?

    29. Name the bacterium that causes typhoid. Mention two diagnostic symptoms. How is this disease transmitted to others?

    30. (a) Explain the phenomena of multiple alllism and co-dominance taking ABO blood group as an example.
     (b) What is the phenotype of the following
                     (i) IAi                      (ii) ii

    31. How does industrial melanism support Darwin’s theory of Natural Selection? Explain.

    32. (a)What is the programme called that is involved in improving success rate of production of desired hybrid and herd size of catfie 7?

     (b) Explain the method used for carrying this programme for cows.

    33. Explain the function or each of the following:
    (a) Coleorhizae
    (b) Umbilical cord
    (c) Germ pores

    34. How is the amplification of a gene sample of interest carried out using Polymerase Chain Reaction (PCR)?


    35. In angiosperm zygote is diploid while primary endosperm is triploid explain?

    36. A cross between a red flower bearing plant and a white flower bearing plant of Arntirrhinum produced all plants having pink flowers. Work out a cross to explain how this is possible

    37. List two main propositions of oparin and Haldane?

    38. Write the event that takes place when a vaccine for any disease is introduced in the body?


    39. Why is a person with cut and bruises following an accident administrated tetanus antitoxin?  Give reason

    40. Name the bacterium responsible for the large hole seen in “Swiss cheese” what are these holes due to?

    41. Name the source of DNA polymerase used in PCR technique. Mention why it is used?

    42. Write any four ways used to introduce a desired DNA segment into bacterial cell in recombinant technology experiments.

    43. Why is proinsulin so called? How is insulin differ from it?

    44. Where would you expect more species biodiversity – in tropical or in polar region? Give reasons in support of your answer?

    45. “It is possible that a species may occupy more than one trophic level in the same eco system at the same time.” Explain with the help of one example.

    45. Suggest and explain any three ART to an infertile couple.


    46. Explain the steps in the formation of an ovum from an oogonium in human

    47. Why is a human female rarely haemophilic? Explain how do haemophilic patient suffer?

    48. In a maternity clinic for some reason the authority are not able to hand over the to two new born their respective real parents. Name and describe the technique that you would suggest to sort out the matter?

    49. Explain the increase in the numbers of melanin (dark winged) moths in the urban areas of post-industrialization period in England.

    50. Describe how biogas is generated from activated sludge. List the components of biogas?

    51. Name the pests that destroy the cotton balls. Explain the role of Bacillis thuringinesis in protecting the cotton crop against the pest to increase the yield.

    52. (a) Write the importance of measuring the size of a population in a habitat or ecosystem.

    (b) Explain with the help of example how the percentage cover is a more meaningful measure of population size than mere number.

    53. Differentiate between types of pyramids of biomass with the help of example.

    54. (a)Describe the endosperm development in coconut.

    (b) Why is tender coconut considered a healthy source of nutrition

    (c) how are pea seed different from castor seeds with respect to endosperm. 


    55. List the symptoms of Ascariasis. How does a healthy person acquire this infection?

    56. Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments? State any three reasons.


    Linkage and crossing-over of genes are alternatives of each other. Justify with the help of an example.

    57. State the difference between the structural genes in a Transcription Unit of Prokaryotes and Eukaryotes.

    58. In Snapdragon, a cross between true-breeding red flowered (RR) plants and true-breeding white flowered (rr) plants showed a progeny of plants with all pink flowers.

    (a)The appearance of pink flowers is not known as blending. Why?

    (b)What is this phenomenon known as?

    59. Write the location and functions of the following in human testes:
    (a) Sertoli cells
    (b) Leydig cells

    60. Construct an age pyramid which reflects an expanding growth status of human population.

    61. Describe the mutual relationship between fIg tree and wasp and comment on the phenomenon that operates in their relationship.

    62. How have transgenic animals proved to be beneficial in:

    (a) Production of biological products

    (b) Chemical safety testing

    63. How does a restriction nuclease function? Explain.

    64. Explain the significant role of the genus Nucleopolyhedrovirus in anecological sensitive area.

    65. Identify a b c d e and f in the table given below





    Characteristic of affected  individuals






    of 21

       ‘a’     (i)






    Overall masculine     development




    45 with XO

    ‘e’     (i)



    66. Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.

    67. A woman has certain queries as listed below, before starting with contraceptive pills. Answer them:
    (a) What do contraceptive pills contain and how do they act as contraceptives?
    (b) What schedule should be followed for taking these pills?

    68. Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.


    Why are angiosperm anthers called dithecous? Describe the structure of its microsporangium.

    69. Since the origin of life on Earth, there were five episodes of mass extinction of species.

    (i) How is the ‘Sixth Extinction’, presently in progress, different from the previous episodes?

    (ii) Who is mainly responsible for the ‘Sixth Extinction’?

    (iii) List any four points that can help to overcome this disaster.

    70. Two types of aquatic organisms in a lake show specific growth patterns as shown below, in a brief period of time. The lake is adjacent to an agricultural land extensively supplied with fertilisers.

    Answer the questions based on the facts given above:

    (i) Name the organisms depicting the patterns A and B.
    (ii) State the reason for the growth pattern seen in A.
    (iii) Write the effects of the growth patterns seen above.

    71. Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endo-nuclease.

    72. Explain, giving three reasons, why tropics show greatest levels of species diversity.

    73. Community Service department of your school plans a visit to a slumarea near the school with an objective to educate the slum dwellers withrespect to health and hygiene.

    (a) Why is there a need to organise such visits?
    (b) Write the steps you will highlight, as a member of this department, in your interaction with them to enable them to lead a healthy life.


    74. What is mutualism ? Mention any two examples where the organisms involved are commercially exploited in agriculture.


    List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

    75. (a) Why are the plants raised through micropropagation termed as somaclones?

    (b) Mention two advantages of this technique.

    76. Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) in it.

    77. (a) Select the analogous structures from the combinations given below:

    (i) Forelimb of whales and bats
    (ii) Eyes of octopus and mammals
    (iii) Tuber of sweet potato and potato
    (iv) Thorns of bouganvillea and tendrils of Cucurbita

    (b) State the kind of evolution they represent.

    78. A moss plant is unable to complete its life-cycle in a dry environment. State two reasons.

    79. A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.
    (a) Write what did the doctor inject into the patient’s body.
    (b) How do you think this injection would protect the patient against the disease ?
    (c) Name the disease against which this injection was given and the kind of immunity it provides.

    80. Explain the significance of satellite DNA in DNA fingerprinting technique.

    89. What does the following equation represent? Explain.

                                        p2 +2 pq + q2

    90. Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

    91. State what is apomixis. Comment on its significance. How can it be commercially used?

    92.State the medicinal value and the bioactive molecules produced by  Streptococcus, Monascus and Trichoderma.


    What are methanogens? How do they help to generate biogas?

    93. Describe any three potential applications of genetically modified plants.

    94. How did an American Company, Eli Lilly use the knowledge of r-DNA technology to produce human insulin?

    95. Explain co-evolution with reference to parasites and their hosts. Mention any four special adaptive features evolved in parasites for their parasitic mode of life.

    96. Rearrange the following in the correct sequence to accomplish an  important biotechnological reaction:

    (a) In vitro synthesis of copies of DNA of interest

    (b) Chemically synthesized oligonucleotides

    (c) Enzyme DNA-polymerase

    (d) Complementary region of DNA

    (e) Genomic DNA template

    (f) Nucleotides provided

    (g) Primers

    (h) Thermostable DNA- polymerase (from Thermus aquaticus)

    (i) Denaturation of ds-DNA

    97. With the help of a flow-chart exhibit the events of eutrophication.

    98. Enumerate any six essentials of good, effective Dairy Farm Management Practices.


    99. A single pea plant in your kitchen garden produces pods with viable seeds. But the individual papaya plant does not. Explain.

    100. Following are the features of genetic codes. What does each one indicate? Stop codon: Unambiguous codon; Degenerate codon: Universal codon.

    101. Suggest four important steps to produce a disease resistant plant through conventional plant breeding technology.
    102. Name a genus of baculovirus. Why are they considered good biocontrol agents?
    103. Explain the relationship between CFC’s and Ozone in the stratosphere.


    Why are sacred groves highly protected?

    104. (a) Name the organic material exine of the pollen grain is made up of. How is this material advantageous to pollen grain?
    (b) Still it is observed that it does not form a continuous layer around the pollen grain. Give reason.
    (c) How are ‘pollen banks’ useful?


    (a) Mention the problems that are taken care of by Reproduction and Child Health Care programme.
    (b) What is amniocentesis and why there is a statutory ban on it?

    105. What is a test cross? How can it decipher the heterozygosity or a plant?

    106. (a) What do ‘Y’ and B’ stand for in ‘YAC’ and ‘BAC’ used in Human Genome Project (HGP). Mention their role in the project.
    (b) Write the percentage of the total human genome that codes for proteins and the percentage of discovered genes whose functions are known as observed during HGP.
    (c) Expand 'SNPs' identified by scientists in HGP.

    107. Differentiate between homology and analogy. Give one example of each.

    108. (a) It is generally observed that the children who had suffered from chicken - pox in their childhood may not contract the same disease in their adulthood. Explain giving reasons the basis of such an immunity in an individual. Name this kind of immunity.
    (b) What are interferons? Mention their role.

    109. (a) Write the two limitations of traditional breeding technique that led to promotion of micro propagation.
    (b) Mention two advantages of micro propagation.
    (c) Give two examples where it is commercially adopted.

    110. (a) How do organic farmers contnol pests? Give two examples.
    (b) State the difference in their approach from that of conventional pest control methods.

    111. (a) Name the selectable markers in the cloning vector pBR322? Mention the role they Play.
    (b) Why is the coding sequence of an enzyme β-galactosidase a preferred selectable marker in comparison to the ones named above?

    112. (a) Why must a cell be made 'competent’ in biotechnology experiments? How does calcium ion help in doing so?
    (b) State the role of ‘biolistic gun' in biotechnology experiments.

    113. Explain enzyme-replacement therapy to treat adenosine deaminase deficiency. Mention two disadvantages of this procedure.

    114. Name and explain the type of interaction that exists in mycorrhizae and between cattle egret and cattle.

    115. Differentiate between primary and secondary succession. Provide one example of each.

    Get the solution for all the questions given here

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