CBSE (Science) Class 12CBSE
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Question Paper Solutions - Biology 2014 - 2015 CBSE (Science) Class 12

Alternate Sets

      

Marks: 70
[1]1

How many chromosomes do drones of honey bees possess?

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Inheritance of Two Genes - Chromosome Theory of Inheritance

Name the type of cell division involved in the production of sperms by honey bees.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Inheritance of Two Genes - Chromosome Theory of Inheritance
[1]2

What is a cistron?

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Transcription - Transcription Unit and the Gene
[1]3

Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible?

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Principles of Biotechnology
[1]4

Why do children cured by enzyme-replacement therapy adenosine deaminase deficiency need periodic treatment?

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine
[1]5

List two advantages of the use of unleaded petrol in automobiles as fuel.

Chapter: [5.04] Environmental Issues
Concept: Air Pollution and Its Control - Introduction of Air Pollution and Its Control
[2]6

Why do moss plants produce very large number of male gametes? Provide one reason. What are these gametes called?

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Pollination
[2]7

(a) Select the homologous structures from the combinations given below:

(i) Forelimbs of whales and bats

(ii) Tuber of potato and sweet potato

(iii) Eyes of octopus and mammals

(iv) Thorns of Bougainvillea and tendrils of Cucurbita

 

(b) State the kind of evolution they represent.

Chapter: [2.03] Evolution
Concept: Evidences for Evolution
[2]8

Why are the plants raised through micropropagation are termed as somaclones?

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

Mention two advantages of micropropagation technique.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Tissue Culture
[2]9

Explain the different steps involved during primary treatment phase of sewage.

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes in Sewage Treatment
[2]10 | Attempt any one of the following
[2]10.1

What is mutualism?

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

Mention any two examples where the organisms involved are commercially exploited in agriculture.

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Interactions
[2]10.2

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

Chapter: [5.03] Biodiversity and Its Conservation
Concept: Biodiversity Conservation
[2]11

State what is apomixis. Comment on its significance. How can it be commercially used?

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Apomixis And Polyembryony
[2]12

During a monohybrid cross involving a tall pea plant with a dwarf pea plant, the offspring populations were tall and dwarf in equal ratio. Work out a cross to show how it is possible.

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]13

Explain the significance of satellite DNA in DNA fingerprinting technique.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: DNA Fingerprinting
[3]14

What does the following equation represent? Explain.

p2 + 2pq + q2 = 1

Chapter: [2.03] Evolution
Concept: Hardy - Weinberg'S Principle
[3]15

A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.

(a) Write what did the doctor inject into the patient’s body.

(b) How do you think this injection would protect the patient against the disease?

(c) Name the disease against which this injection was given and the kind of immunity it provides.

Chapter: [3.01] Human Health and Diseases
Concept: Concept of Immunity
[3]16

Enumerate any six essentials of good, effective Dairy Farm Management Practices.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Animal Husbandry
[3]17 | Attempt any one of the following
[3]17.1

State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes as Biocontrol Agents
[3]17.2

What are methanogens?

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes in Production of Biogas

How do methanogens help to generate biogas?

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes in Production of Biogas
[3]18

Rearrange the following in the correct sequence to accomplish an important biological reaction:

(a) In vitro synthesis of copies of DNA of interest

(b) Chemically synthesized oligonucleotides

(c) Enzyme DNA-polymerase

(d) Complementary region of DNA

(e) Genomic DNA template

(f) Nucleotides provided

(g) Primers

(h) Thermostable DNA-polymerase (from Thermus aquaticus)

(i) Denaturation of ds-DNA

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Principles of Biotechnology
[3]19

Describe any three potential applications of genetically modified plants.

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Agriculture
[3]20

How did an American Company, Eli Lilly use the knowledge of r-DNA technology to produce human insulin?

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Medicine
[3]21

How do snails, seeds, bears, zooplanktons, fungi and bacteria adapt to conditions unfavourable for their survival?

Chapter: [5.01] Organisms and Populations
Concept: Population and Ecological Adaptations
[3]22

With the help of a flow chart, show the phenomenon of biomagnifications of DDT in an aquatic food chain.

Chapter: [5.02] Ecosystem
Concept: Energy Flow
[3]23

Your school has been selected by the Department of Education to organize and host an interschool seminar on “Reproductive Health – Problems and Practices”. However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is “too embarrassing.” Put forth four arguments with appropriate reasons and explanation to justify the topic to be very essential and timely.

Chapter: [1.04] Reproductive Health
Concept: Reproductive Health (Questios)
[5]24 | Attempt an one of the following
[5]24.1

(a) Plan an experiment and prepare a flow chart of the steps that you would follow to ensure that the seeds are formed only from the desired sets of pollen grains. Name the type of experiment that you carried out.

(b) Write the importance of such experiments

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Stamen, Microsporangium and Pollen Grain
[5]24.2

Describe the role of pituitary and ovarian hormones during the menstrual cycle in a human female.

Chapter: [1.03] Human Reproduction
Concept: Menstrual Cycle
[5]25 | Attempt any one of the following
[5]25.1

(a) Why are thalassemia and haemophilia categorized as Mendelian disorders? Write the symptoms of these diseases. Explain their pattern of inheritance in humans.

(b) Write the genotypes of the normal parents producing a haemophilic son.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Genetic Disorders - Mendelian Disorders
[5]25.2

How do m-RNA, t-RNA and ribosomes help in the process of translation?

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Transcription - Introduction of Transcription
[5]26 | Attempt any one of the following
[5]26.1

List the different attributes that a population has and not an individual organism.

Chapter: [5.01] Organisms and Populations
Concept: Population and Ecological Adaptations
[5]26.2

“It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted.” Explain with the help if examples and sketches.

Chapter: [5.02] Ecosystem
Concept: Ecological Pyramids
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