12th Biology Paper Solutions Set 3 : 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 :

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.

Q2 :

Write the importance of MOET. (1)


Answer :

The technique is used to increase the successful rate of production of hybrids in short duration of time.

Q3 :

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


Answer :

The tapetum is the innermost layer of a microsporangium, which is found in a cluster of two in each lobe of an anther. The tapetum is responsible for nourishing the pollen grains. Hence, if it malfunctions then the pollen grains will not be provided with sufficient nutrition and will not be able to mature into viable male gametes.

Q4 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q5 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q6 :

“Sweet potato tubers and potato tubers are the result of convergent evolution.” Justify the statement. (1)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q7 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q8 :

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 :

Please Register/Login to get access to all solutions Facebook Login
Q9 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q10 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q11 :

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 :

Please Register/Login to get access to all solutions Facebook Login
Q12 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q13 :

Explain the steps that ensure cross pollination in an autogamous flower. (2)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q14 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q15 :

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)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q16 :

A student on a school picnic to park on a windy day started sneezing and having difficulty in breathing in 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. (2)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q17 :

Why and how bacteria can be made “competent”™? (2)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q18 :

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

(b) Mention the cause of and one cure for this deficiency. (2)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q19 :

(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). Explain the pattern of inheritance exhibited. (3)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q20 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q21 :

(a) Differentiate between inbreeding and outbreeding.

(b) Explain inbreeding depression and how it can be overcome.

(c) Mention two advantages of inbreeding programme in cattle. (3)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q22 :

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

(b) Name the bioactive molecules produced by Trichoderma polysporum and Monascus purpureus. (3)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q23 :

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) (3)


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q24 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q25 :

How have human activities caused desertification? Explain.

OR

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q26 :

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q27 :

(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 :

Please Register/Login to get access to all solutions Facebook Login
Q28 :

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 :

Please Register/Login to get access to all solutions Facebook Login
Q29 :

Draw a diagram of a mature embryo sac of an angiosperm and label the following parts in it.

(i) Filiform apparatus

(ii) Synergids

(iii) Central cell

(iv) Egg cell

(v) Polar nuclei

(vi) Antopodals

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

OR

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

(b) Write two differences between Oogensis and spermatogenesis.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q30 :

Describe the asexual and sexual phases of life cycle of Plasmodium that 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 :

Please Register/Login to get access to all solutions Facebook Login

12th Biology Paper Solutions Set 2 : 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.