Question Bank Class Xii Biology

QUESTION BANK CLASS XII BIOLOGY

1. Why do the symptoms of malaria not appear immediately after the entry of sporozites into the human body when bitten by female Anopheles? Explain.

2. Give the scientific name of the malarial parasite that causes malignant malaria in humans?

3. An antibody is represented as H2L2 .Explain

4. Why are genes encoding resistance to antibiotics considered useful selectable markers for E.coli cloning vector? Explain with the help of one example

5. Explain the different stages of oogenesis in humans starting from foetal life till its completion. When and where in the body is oogenesis completed?

6. What is a bioreactor?Draw a labelled diagram of a sparged-stirred bio-reactor.Explain its functioning.

7. Draw a longitudinal section of a post-pollinated pistil showing entry of pollen tube into a mature embryo-sac.Labelfiliform apparatus,chalazalend,Hilum,antipodals,male gametes and secondary nucleus?

8. Describe the initiation process of transcription in bacteria?

9. Draw and explain a logistic curve for a population of density (N) at time (t) whose intrinsic rate of narural increase is (r) and carrying capacity is (k)?

10. Write Hardy-weinberg principle and explain the three different ways the natural slection can affect the frequency of a heritable trait in a population shown in the graph given below?

11.EcoRI is a restriction endonuclease.How is it namedso? Explain

12. Write the sequence of DNAbases that the enzyme recognizes.Mention the point at which the enzyme makes a cut inthe DNAsegment?

13. MOET is a good technology to increase the herd size of high yielding cattle .how is it done? Explainthe procedure.

14. Name and describe the technique that will help in solving a case of paternity dispute over the custody of a child by twodifferent families?

15. Differentiate between in-situ and ex-situ approaches of conservation of biodiversity?

16. With the help of diagrams show the different steps in the formation of recombinant DNA by action of restriction endonuclease enzyme EcoRI?

17. With the help of graphical illustration only, show the changes in the levels of the pituitary hormone during a menstrual cycle in humans?

18. Explain the mechanism of replication of a retrovirus in a human cell.

19. Draw a neat labelled diagram of nucleosome? Mention what enables histones to acquire a positive charge?

20.Explain the signification of ecological pyramids with the help of an examples or Why are the pyramids referred to as upright or inverted ?explain

21. Give one examples each of albuminous and non albuminous seeds or Name the part of ovule and the embryo sac of an angiosperm that develop into 1.perisperm,2.seed coats 3.endosperm 4.embryonal axis ?

22. Multiple alleles can be found only when population studies are made .explain with the help of an example in humans?

23. List any two molecular diagnostic techniques and write one application of each of them?

24. Explain the three steps involved in each cycle of polymerase chain-reaction?

25. Explain the chemical structure of a single stranded polynucleotide chain?

26. Describe the salient features of the double-helix structure of DNA molecule?

27. Write the function of adenosine deaminase enzyme .state the cause of ADA deficiency in human .mention a possible permanent cure for a ADA deficiency patient?

28. Differentiate between inbreeding and outbreeding incattle.state one advantage and one disadvantages for each one of them ?

29. Explain the steps in the formation of an ovum from an oogonium in humans?

30. Suggest and explain any three Assisted Reproductive Technologies to an infertile couple ?

31. Differentiate between two different types of pyramids of biomass with the help of one example of each ?

32.Mention the contribution of S.L. Miller’s experiments on origin of life ?

33.Explain co-dominance taking an example of human blood group in the population ?

34. Name the cell HIV attacks first when it gains entry into a human body .How does this virus replicate further to cause immune deficiency in the body ?

35.How is the Bt cotton plant created as a GM plants ? how is it protected against boll worm infestation ?

36.Explain in sequence the process of amplification of a gene of interest using polymerase chain reaction ?

37. Explain the process of megasporogenesis in angiosperms ?

38. List and explain the events that follow the journey of human zygote until its implantation ?

39.Explain why it is scientifically incorrect to blame the mother for bearing female child ?

40.Explain Mendel’s law of independents assortment by taking a sutable example?

41.How did Morgan show the deviation in inheritance pattern in drosophila with respect to this law ?

42.Describe the structure of a RNA poynucleotide chain having four different types of nucleotides ?

43.Why is human ABO blood group gene considered a good example of multiple alleles ?

44.Frederich Griffith claimed that R-strain streptococcus pneumonia had been transformed by heat killed S-strain bacteria.Explain the findings

45.Why is biofortification considered as the most practical means to improve public health?Explain taking three examples.

46.Explain the process of emasculation and bagging of flowers .state their importance in breeding experiments.

47.Draw a labelled diagram of the microscopic structure of human sperm.explain the functions of each part ?

48.Why did Meselson and Stahl use 14N and 15N isotopes in the sources of nitrogen present in the culture medium in their experiment?Explain

49.A mother of a one year old daughter wanted to space her second child.her doctor suggested CuT.Explain its contraceptive action ?

50.What is bio-magnifacation ?Diagramatically represent the process of biomagnifications of DDT in an aquatic food chain ?

51.What is satellite DNA in a genome ?Explain their role in DNA fingerprinting ?

52.What does BOD of a water body stand for ?How is it related to water pollution ?

53.Draw a diagram of T.S of a part of seminiferous tubule of testis of an adult human male and label any four parts in it ?

54.Draw the sectional view of the female reproductive system and label its different parts ?

55.Draw the sectional view of male reproductive system ?

56.Which method is commonly used for improving the cattle breeds and why ?

56.“Sweet potato tubers and potato tubers are the result of convergent evolution” Justify the statement.

57.Explain why very small animals are rarely found in polar region.

58Explain the steps that ensure cross pollination in an autogamous flower.

59A student on a school picnic to a park on a windy day started sneezing and having difficulty in breathing on reaching the park. The teacher enquired whether the student was allergic to something.

(a)What is an allergy ?

(b)Write the two unique characteristics of the system involved in the response observed in the student.

60. Why and how bacteria can be made ‘competent’ ?

61. (a) Name the deficiency for which first clinical gene therapy was given.

(b) Mention the cause of and one cure for this deficiency.62. Draw the following diagrams related to human reproduction and label them.

(a) The zygote after the first cleavage division.

(b) Morula stage.

(c) Blastocyst stage (sectional view).63. (a) Draw a diagram of a mature embryo sac of an angiosperm and lable the following parts in it :

(i) Filiformapparatus (ii) Synergids (iii) Central cell (iv) Egg cell(v) polar nuclei (vi) Antipodals

(b) Write the fate of egg cell and polar nuclei after fertilization.

(c) Describe the events of Oogenesis with the help of schematic representation.

(d) Write two differences between Oogenesis and Spermatogenesis.

64.Name an organism where cell division in itself is a mode of reproduction.

65.When does a human body elicit an anamnestic response ? 66.Name any two diseases the ‘Himgiri’ variety of wheat is resistant to. 67.State the role of transposons in silencing of mRNA in eukaryotic cells.

68.Why are green algae not likely to be found in the deepest strata of the ocean ?

69.State what ‘standing crop’ of a trophic level represents.

70.Why is the use of unleaded petrol recommended for motor vehicles equipped with catalytic converters?

71.Name the type of biodiversity represented by the following:

(i) 1000 varieties of mangoes in India.

(ii) Variations in terms of potency and concentration of reserpine in Rauwolfiavomitoria growing in different regions of Himalayas.

72.In angiosperms, zygote is diploid while primary endosperm cell is triploid. Explain.

73. WHY DO Intermodal segments fail to propagate vegetaively even when they are in contact with damp soil ?

74. Mention any two probable reasons for rapid rise of population in our country from about 350 million at the time of independence to about 1 billion by the year 2000.

75 The gene that control the ABO blood grouping in human beings has three alleles IA,IB and I.

a)How many different genotype are likely to be present in the human population ?

b) Also how many phenotypes are possibly present?

76. state any one reason to explain why RNA virusis mutate and evolve faster than other adolescents.

77.Mention any two measures for prevention and control of alcohol and drug abuse among adolescents.

78.what would be the impact on the environment around a thermal power plant if its electrostatic precipitator stopfunctioning? Give a Reason.

79. Why is thermoregulation more effectively achieved in larger animals than in smaller ones?

80. A plasmid and a DNA sequences in a cell need to be cut for producing recombinant DNA. Name the enzymewhich acts as molecular scissors to cut the DNA segments.

81. Even though each pollen grain has two gametes, why are at least 10 pollen grain and 5pollen grain reguired to fertilise 10 ovules present in a particular carpel?

82.when a red flowered Antirrhinum plant was crossed with a white flowered Antirrhinum plant, the F1 –offspring had pink flower. Mention (a) the genotype of F1plant and (b) the reason why it did not bear the parental red orwhite flower colour?

83.Draw schematically asingle polynucleotidestrand (with at least three nucleotides). Provide labels and directions.

84.Choose and rearrange any four of the following groups of plant in an ascending evolutionary scale. Cycads; gnetales ; monocotyledons: Rhynia – like plant :cholorophyta ancestors :Dicotyledons: and seed ferns.

85.Fill in the blanks in the different columns of the table below:

86.Name any two sources of e-Wastes and write two diffent ways for their disposal. 87.Why the pyramid of energy is always upright ? Expain. 88.Explain why very small animals are rarely found in polar region. 89.Draw a diagram of the microscopic strucure of human sperm. Label the following parts in it and write their functions. (a)Acrosome (b)Nucleus (C)Middle piece

90.With the help of any two suitable examples explain the effect of anthropogenic actions on

Organic evolution.

91.(a)Why is human ABO blood group gene considered a good example of multiple alleles?

(b)Work out a cross up to F1 generation only,between a mother with blood group A (homozygous) and the father with blood group B (homozygous).Exlain the pattern of inheritance exhibited.

92.Describe the structure of a RNA polynucleotide chain having four different type of nucleotides.

93.Differentiate between inbreeding and outbreeding in cattle. State one advantage and one disadvantage for each one of them.

94.(a)Why are the fruit juices bought from market clearer as comared to those made at home? (b)Name the bioactive molecules produced by Trichoderma ploysporum and Monascuspurpureus.

95.(a)Why are transgenic animals so called?

(b)Expain the role of transgenic animals in (i)Vaccine safety and (ii) Biological products with the

Help of an example each.

96.How have human activities caused desertification ? Explain. 97. How does algal bloom destroy the quality of a fresh water body? Explain.

98.Explain mutualism with the help of any two examples.How is it different from commensalism?

99.(a)Draw a diagrammatic sectional view of a mature anatropous ovule and label the following parts in it:

(i)that develops into seed coat.

(ii)thatdevelpos into an embryo after fertilization.

(iii)that develops into an endosperm in an albuminous seed.

(iv)throught which the pollen tube gains entry into the embryo sac.

(v)that attaches the ovule to the placenta.

(b)Describe the charateristic features of wind pollinated flowers .

100. (a)Draw a diagrammatic sectional view of the female reproductive system of human and label the parts:

(i)where the secondary oocytes develop

(ii)which helps in collection of ovum after ovulation

(iii)where fertilization occurs

(iv)where implantation of embryo occurs.

(b)Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females.

101 .Describe the asexual phases of life cycle of Plasmodium that causes malaria in humans.

102. (a)what is plant breeding ? List the two steps the classical plants breeding involves.

(b)How has the mutation breeding helped in improving crop varieties? Give one example where this technique has helped.

(c)How has the breeding programme helped in improving the public nutritional health? State two examples in support of your answer.

103.Achildernsuffering from Thalassemia is born to a normal couple.But the mother is being blamed by the family for delivering a sick baby.

(a)what is Thalassemia ??

(b) how would you counsel the family not to blame the mother for delivering a child suffering from this disease? Explain.

(c)List the values you counselling can propagate in the families.