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Question Paper Solutions - Biology 2017 - 2018-CBSE 12th-Class 12 CBSE (Central Board of Secondary Education)

Alternate Sets

   

Marks: 70
[1]1

Write the dual purpose served by Deoxyribonucleoside triphosphates in the polymerisation.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Structure of Nucleotide
[1]2

Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes.

Chapter: [9.01] Human Health and Diseases
Concept: Common Diseases in Humans
[1]3

How do cytokine barriers provide innate immunity in humans?

Chapter: [9.01] Human Health and Diseases
Concept: Concept of Immunity
[1]4

Write the names of the following:

A 15 mya primate that was ape-like

Chapter: [2.03] Evolution
Concept: Origin and Evolution of Man

Write the names of the following:

A 2 mya primate that lived in East African grasslands

Chapter: [2.03] Evolution
Concept: Origin and Evolution of Man
[1]5

Mention the chemical change that proinsulin undergoes, to be able to act as mature insulin

Chapter: [4.02] Biotechnology and Its Application
Concept: Introduction of Biotechnology and Its Application
[2]6

Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.

1) Recommend two microbes that can enrich the soil with nitrogen

2) Why do leguminous crops not require such enrichment of the soil? 

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes as Biofertilisers
[2]7 | Attempt Any One
[2]7.1

With the help of an algebraic equation, how did Hardy-Weinberg explain that in a given population the frequency of occurrence of alleles of a gene is supposed to remain the same through generations?

Chapter: [2.03] Evolution
Concept: Hardy - Weinberg'S Principle
[2]7.2

Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: The DNA - Packaging of Dna Helix
[2]8

How did a citizen group called Friends of Arcata Marsh Arcata, California, USA, help to improve the water quality of the marshland using Integrated Waste Water Treatment? Explain in four steps.

Chapter: [5.04] Environmental Issues
Concept: Water Pollution and Its Control - A Case Study of Integrated Waste Water Treatment
[2]9

You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Tissue Culture
[2]10

Name the source plant of heroin drug. How is it obtained from the plant?

Chapter: [3.01] Human Health and Diseases
Concept: Drugs and Alcohol Abuse - Effects of Drug/Alcohol Abuse

Write the effects of heroin on the human body.

Chapter: [3.01] Human Health and Diseases
Concept: Drugs and Alcohol Abuse - Effects of Drug/Alcohol Abuse
[3]11

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: [11.01] Human Reproduction
Concept: Gametogenesis
[3]12

Expand VNTR and describe its role in DNA fingerprinting.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: DNA Fingerprinting

Give the applications of DNA fingerprinting technique.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: DNA Fingerprinting
[3]13

Differentiate between Parthenocarpy and Parthenogenesis. Give one example of each.

Chapter: [1.01] Reproduction in Organisms
Concept: Introduction of Sexual Reproduction
[3]14

Medically it is advised to all young mothers that breastfeeding is the best for their newborn babies. Do you agree? Give reasons in support of your answer.

Chapter: [11.01] Human Reproduction
Concept: Pregnancy and Embryonic Development
[3]15

Explain the mechanism of 'sex determination' in birds. How does it differ from that of human beings?

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Sex Determination - Introduction of Sex Determination
[3]16

How has the development of bioreactor helped in biotechnology?

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

Name the most commonly used bioreactor and describe its working.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Principles of Biotechnology
[3]17

Explain the roles of the following with the help of an example each in recombinant DNA technology :

Restriction Enzymes

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

Explain the roles of the following with the help of an example each in recombinant DNA technology :

Plasmids

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Tools of Recombinant Dna Technology - Competent Host (For Transformation with Recombinant Dna)
[3]18

Explain out-breeding, out-crossing and cross-breeding practices in normal husbandry.

Chapter: [9.02] Animal Husbandry
Concept: Animal Husbandry
[3]19

Organic farmers prefer the biological control of diseases and pests to the use of chemicals for the same purpose. Justify

Chapter: [3.02] Microbes in Human Welfare
Concept: Microbes as Biocontrol Agents

Give an example of a bacterium, a fungus and an insect that are used as biocontrol agents

Chapter: [3.02] Microbes in Human Welfare
Concept: Microbes as Biocontrol Agents
[3]20

Differentiate between analogous and homologous structures.

Chapter: [2.03] Evolution
Concept: Evidences for Evolution
[3]21 | Attempt Any One
[3]21.1

'India has greater ecosystem diversity than Norway." Do you agree with the statement? Give reasons in support of your answer.

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

Write the difference between genetic biodiversity and species biodiversity that exists at all the levels of biological organisation.

Chapter: [5.03] Biodiversity and Its Conservation
Concept: Concept of Biodiversity
[3]21.2

Explain the effect on the characteristics of a river when urban sewage is discharged into it.

Chapter: [5.03] Biodiversity and Its Conservation
Concept: Concept of Biodiversity
[3]22

How has the use of Agrobacterium as vectors helped in controlling Meloidogyne incognita infestation in tobacco plants? Explain in the correct sequence.

Chapter: [4.02] Biotechnology and Its Applications
Concept: Biotechnological Applications in Agriculture
[4]23

Looking at the deteriorating air quality because of air pollution in many cities of the country, the citizens are very much worried and concerned about their health. The doctors have declared the health emergency in the cities where the air quality is very severely poor.

1) Mention any two major causes of air pollution.

2) Write any two harmful effects of air pollution to plants and humans.

3) As a captain of your school Eco-club, suggest any two programmes you would plan to organise in the school so as to bring awareness among the students on how to check air pollution in and around the school.

 

Chapter: [5.04] Environmental Issues
Concept: Air Pollution and Its Control - Introduction of Air Pollution and Its Control
[5]24 | Attempt Any One
[5]24.1

Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Double Fertilisation

Explain the events up to double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Double Fertilisation
[5]24.2

Explain menstrual cycle in human females.

Chapter: [11.01] Human Reproduction
Concept: Menstrual Cycle

How can the scientific understanding of the menstrual cycle of human females help as a contraceptive measure?

Chapter: [11.01] Human Reproduction
Concept: Menstrual Cycle
[5]25 | Attempt Any One
[5]25.1

Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Inheritance of Two Genes - Linkage and Crossing Over

How did Sturtevant explain gene mapping while working with Morgan?

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Inheritance of Two Genes - Linkage and Crossing Over
[5]25.2

State the 'Central dogma' as proposed by Francis Crick. Are there any exceptions to it? Support your answer with a reason and an example.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Search for Genetic Material - Introduction of Search for Genetic Material

Explain how the biochemical characterisation (nature) of 'Transforming Principle' was determined, which was not defined from Griffth's experiments.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Search for Genetic Material - Introduction of Search for Genetic Material
[5]26 | Attempt Any One
[5]26.1

Following are the responses of different animals to various abiotic factors. Describe each one with the help of an example.

1) Regulate

2) Conform

3) Migrate

4) Suspend

Chapter: [5.01] Organisms and Populations
Concept: Organism and Its Environment - Major Abiotic Factors

If 8 individuals in a population of 80 butterflies die in a week, calculate the death rate of the population of butterflies during that period.

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Growth
[5]26.2

What is a trophic level in an ecosystem? What is 'standing crop' with reference to it?

Chapter: [5.02] Ecosystem
Concept: Ecosystem – Structure and Function

Explain the role of the 'first trophic level' in an ecosystem.

Chapter: [5.02] Ecosystem
Concept: Ecosystem – Structure and Function

How is the detritus food chain connected with the grazing food chain in a natural ecosystem?

Chapter: [5.02] Ecosystem
Concept: Ecosystem – Structure and Function
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