CBSE (Commerce) Class 12CBSE
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Question Paper Solutions - Biology 2012 - 2013 CBSE (Commerce) Class 12


Marks: 70
[1]1

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

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Stamen, Microsporangium and Pollen Grain
[1]2

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

Chapter: [3.01] Human Health and Diseases
Concept: Human Health and Diseases (Questions)
[1]3

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

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Replication - The Experimental Proof
[1]4

Identify the examples of convergent evolution from the following: 

(i) Flippers of penguins and dolphins

(ii) Eyes of octopus and mammals

(iii) Vertebrate brains

Chapter: [2.03] Evolution
Concept: Evolution (Questions)
[1]5

Write the importance of MOET.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Animal Husbandry
[1]6

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

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Tools of Recombinant Dna Technology - Restriction Enzymes
[1]7

Name the type biodiversity represented by the following: 

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

(b) Estuaries and alpine meadows in India

Chapter: [5.03] Biodiversity and Its Conservation
Concept: Concept of Biodiversity
[1]8

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

Chapter: [5.02] Ecosystem
Concept: Productivity
[2]9

Geitonogamous flowering plants are genetically autogamous but functionally cross-pollinated. Justify.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Pollination
[2]10

When and where do chorionic villi appear in humans?

Chapter: [1.03] Human Reproduction
Concept: Pregnancy and Embryonic Development

State the Function of Chorionic Villi

Chapter: [1.03] Human Reproduction
Concept: Pregnancy and Embryonic Development
[2]11

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.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Elementary Idea of Polygenic Inheritance
[2]12

A student on a school trip started sneezing and wheezing soon after reaching the hill station for no explained reasons. But, no return to the plains, the symptoms disappeared. What is such a response called? How does the body produce it?

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Stamen, Microsporangium and Pollen Grain
[2]13

Name two commonly used bioreactors.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Processes of Recombinant Dna Technology

State the importance of using a bioreactor.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Processes of Recombinant Dna Technology
[2]14

Write the function of adenosine deaminase enzyme.

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine

State the cause of ADA deficiency in humans.Mention a possible cure for an ADA deficiency patient.

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine
[2]15 | Attempt any one of the following
[2]15.1

Expand the Given and mention one application of each:

PCR

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine

Expand the Given and mention one application of each:

ELISA

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine
[2]15.2

Mention the difference in the mode of action of exonuclease and endonuclease.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Tools of Recombinant Dna Technology - Restriction Enzymes

How does restriction endonuclease function?

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Tools of Recombinant Dna Technology - Restriction Enzymes
[2]16

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

Chapter: [5.04] Environmental Issues
Concept: Radioactive Waste Management and E-waste
[2]17

Why the pyramid of energy is always upright? Explain.

Chapter: [5.02] Ecosystem
Concept: Ecological Pyramids
[2]18

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

Chapter: [5.01] Organisms and Populations
Concept: Organism and Its Environment - Responses to Abiotic Factors
[3]19

Draw a diagram of the microscopic structure of human sperm. Label the following parts in it and write their functions

(a) Acrosome

(b) Nucleus

(c) Middle piece

Chapter: [1.03] Human Reproduction
Concept: Gametogenesis
[3]20

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

Chapter: [2.03] Evolution
Concept: Evidences for Evolution
[3]21

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

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Deviations from Mendelism - Incomplete Dominance, Co-dominance, Multiple Alleles and Inheritance of Blood Groups, Pleiotropy

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.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Deviations from Mendelism - Incomplete Dominance, Co-dominance, Multiple Alleles and Inheritance of Blood Groups, Pleiotropy
[3]22

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

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Structure of Nucleotide
[3]23

Differentiate between inbreeding and outbreeding in cattle.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Animal Husbandry

State the disadvantage of inbreeding among cattle. How it can be overcome?

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Animal Husbandry
[3]24

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

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes in Industrial Production

Name the bioactive molecules produced by Trichoderma polysporum and Monascus purpureus.

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes as Biocontrol Agents
[3]25

Why a transgenic animals so called?

Chapter: [4.02] Biotechnology and Its Application
Concept: Transgenic Animals

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

Chapter: [4.02] Biotechnology and Its Application
Concept: Transgenic Animals
[3]26 | Attempt any of the following
[3]26.1

How have human activities caused desertification? Explain.

Chapter: [5.04] Environmental Issues
Concept: Degradation by Improper Resource Utilisation and Maintenance
[3]26.2

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

Chapter: [5.04] Environmental Issues
Concept: Water Pollution and Its Control - Introduction of Water Pollution and Its Control
[3]27

Explain mutualism with the help of any two examples.

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Interactions

How is mutualism different from commensalism?

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Interactions
[5]28 | Attempt any one of the following
[5]28.1

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

(i) that develops into seed coat.

(ii) that develops into an embryo after fertilization.

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

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

(v) that attaches the ovule to the placenta.

 

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - The Pistil, Megasporangium (Ovule) and Embryo Sac

Describe the characteristic features of wind pollinated flowers.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Pollination
[5]28.2

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.

Chapter: [1.03] Human Reproduction
Concept: The Female Reproductive System

Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females

Chapter: [1.03] Human Reproduction
Concept: Menstrual Cycle
[5]29 | Attempt any one of the following
[5]29.1

Describe the asexual and sexual phases of life cycle of Plasmodium that causes malaria in humans

Chapter: [3.01] Human Health and Diseases
Concept: Common Diseases in Humans
[5]29.2

What is plant breeding?

 

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Plant Breeding

List the two steps the classical plant breeding involves.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Plant Breeding

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

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Plant Breeding

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

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Plant Breeding
[5]30 | Attempt any one of the following

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. 

(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.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Genetic Disorders - Mendelian Disorders
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