12th Biology Paper Solutions Set 2 : CBSE Delhi Previous Year 2013

General Instructions:
(i) All questions are compulsory.
(ii) This question paper consists of four Sections A, B, C and D. Section A contains 8 questions of one mark each, Section B is of 10 questions of two marks each, Section C is of 9 questions of three marks each and Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and two questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
Q1 :

Write the equation that helps in deriving the net primary productivity of an ecosystem. (1)


Answer :

Net primary productivity (NPP) in an ecosystem can be derived using the following equation: NPP = GPP (Gross primary productivity) − R (Respiratory losses)

Q2 :

Name the type biodiversity represented by the following: (1)

(a) 50,000 different strains of rice in India.

(b) Estuaries and alpine meadows in India


Answer :

(a) Genetic diversity

(b) Ecological diversity

Q3 :

Why is the enzyme cellulase needed for isolating genetic material from plant cells and not form the animal cells? (1)


Answer :

Plant cells have cell wall made up of cellulose where as animal cells lack cell wall and do not contain cellulose. Therefore the enzyme cellulase is needed for isolating genetic material from plant cells only.

Q4 :

Write the importance of MOET. (1)


Answer :

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Q5 :

Identify the examples of homologous structures from the following: (1)

(i) Vertebrate hearts

(ii) Thorns in Bougainvillea and tendrils of Cucurbita.

(iii) Food storage organs in sweet potato and potato.


Answer :

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Q6 :

Name the enzyme and state its property that is responsible for continuous and discontinuous replication of the two strands of a DNA molecule.(1)


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Q7 :

Why sharing of injection needles between two individuals is not recommended? (1)


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Q8 :

An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give any one reason. (1)


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Q9 :

Describe the gene therapy procedure for an ADA-deficient patient. (2)


Answer :

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Q10 :

Expand the following and mention one application of each:

(i) PCR

(ii) ELISA

OR

(a) Mention the difference in the mode of action of exonuclease and endonuclease.

(b) How does restriction endonuclease function? (2)


Answer :

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Q11 :

Name any two sources of e-Wastes and write two difference ways of their disposal. (2)


Answer :

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Q12 :

Why the pyramid of energy is always upright? Explain. (2)


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Q13 :

Explain why very small animals are rarely found in polar region. (2)


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Q14 :

(a) How does cleistogamy ensure autogamy?

(b) State one advantage and one disadvantage of cleistogamy to the plant. (2)


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Q15 :

When and where do chorionic villi appear in humans? State their function. (2)


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Q16 :

In a cross between two tall pea plants some of the offsprings produced were dwarf. Show with the help of Punett square how this is possible. (2)


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Q17 :

A young boy when brought a pet dog home started to complain of watery eyes and running nose. The symptoms disappeared when the boy was kept away from the pet.

(a) Name of type of antibody and the chemicals responsible for such a response in the boy.

(b) Mention the name of any one drug that could be given to the boy for immediate relief from such a response. (2)


Answer :

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Q18 :

(a) Explain how to find whether an E. coli bacterium has transformed or not when a recombinant DNA bearing ampicillin resistant gene is transferred into it.

(b) What does the ampicillin resistant gene act as in the above case? (2)


Answer :

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Q19 :

(a) Why are the fruit juices bought from market clearer as compared to those made at home?

(b) Name the bioactive molecules produced by Trichodermapolysporumand Monascuspurpureus.(3)


Answer :

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Q20 :

(a) Why a transgenic animals so called?

(b) Explain the role of transgenic animals in (i) Vaccine safety and (ii) Biological products with the help of an example each.(3)


Answer :

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Q21 :

How have human activities caused desertification? Explain.

OR

How does algal bloom destroy the quality of a fresh water body? Explain. 3


Answer :

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Q22 :

(a) Explain how to overcome inbreeding depression in cattle.

(b) List three advantages of inbreeding in cattle.

(c) Name an improved breed of cattle.


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Q23 :

Explain mutualism with the help of any two examples. How is it different from commensalism? (3)


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Q24 :

Describe the structure of RNA polynucleotide chain having four different types of nucleotides. (3)


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Q25 :

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

(b) Work out a cross up to F1generation only, between a mother with blood group A (Homozygous) and the father with blood group B (Homozygous). Explain the pattern of inheritance exhibited. (3)


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Q26 :

With the help of any two suitable examples explain the effect of anthropogenic actions on organic evolution.(3)


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Q27 :

(a) Draw a diagram of the structure of a human ovum surrounded by corona radiate. Label the following parts:

(i) Ovum

(ii) Plasma Membrane

(iii) State the function of Zona Pellucida.(3)


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Q28 :

Describe the asexual and sexual phases of life cycle of Plasmodiumthat causes malaria in humans. (5)

OR

(a) What is plant breeding? List the two steps the classical plant 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.


Answer :

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Q29 :

A child suffering from Thalassemia is born to a normal couple. But the mother is being blamed by the family for delivering a sick baby. (5)

(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 your counselling can propagate in the families.


Answer :

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Q30 :

(a) Draw a labeled schematic diagram of the transverse section of a mature anther of an angiosperm plant.

(b) Describe the characteristic feature of an insect pollinated flower.

OR

(a) Describe the events of spermatogenesis with the help of a schematic representation.

(b) Write two differences between spermatogenesis and oogenesis.


Answer :

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12th Biology Paper Solutions Set 3 : CBSE Delhi Previous Year 2013 will be available online in PDF book soon. The solutions are absolutely Free. Soon you will be able to download the solutions.