PUC Karnataka Science Class 12CBSE
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Biology 57/3/2 2018-2019 PUC Karnataka Science Class 12 Question Paper Solution

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Biology
57/3/2
2018-2019 March
Marks: 70

SECTION - A
[1]1

Why are cucurbit plants said to be monoecious ?

Concept: Reproduction in Organisms (Questions)
Chapter: [1.01] Reproduction in Organisms
[1]2
[1]2.a

Name the pollutant attributed to be the cause of ‘ozone-hole’ over the Antarctica region.

Concept: Ozone - Ozone Depletion in the Stratosphere
Chapter: [5.04] Environmental Issues
OR
[1]2.b

List the greenhouse gases other than carbon dioxide.

Concept: Greenhouse Effect and Climate Change
Chapter: [5.04] Environmental Issues
[1]3
[1]3.a

Write the scientific name of the organism Alexander Fleming worked on and discovered the first antibiotic.
Was the organism he worked on a fungus or a bacterium ?

Concept: Microbes in Human Welfare (Questions)
Chapter: [3.03] Microbes in Human Welfare
OR
[1]3.b

Suggest a method to overcome excessive inbreeding depression.

Concept: Animal Husbandry
Chapter: [3.02] Strategies for Enhancement in Food Production
[1]4

According to de-Vries what is saltation?

Concept: Mechanism of Evolution
Chapter: [2.03] Evolution
[1]5

Differentiate between a DNA and a RNA nucleotide.

Concept: Search for Genetic Material - Properties of Genetic Material (DNA Versus RNA)
Chapter: [2.02] Molecular Basis of Inheritance
SECTION - B
[2]6

Where exactly is the filiform apparatus present in the embryo-sac of an angiosperm ?
States its function.

Concept: Development of Female Gametophytes
Chapter: [1.02] Sexual Reproduction in Flowering Plants
[2]7

Explain the role of histones in forming a nucleosome.

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

What is ‘Ori’ ? State its importance during cloning of a vector.

Concept: Tools of Recombinant Dna Technology - Cloning Vectors
Chapter: [4.01] Biotechnology - Principles and Processes
OR
[2]8.b

Explain the importance of ‘Selectable marker’, with the help of a suitable example.

Concept: Tools of Recombinant Dna Technology - Cloning Vectors
Chapter: [4.01] Biotechnology - Principles and Processes
[2]9

What is ‘carrying capacity’ of a species in a habitat ? Why is logistic growth model considered more realistic?

Concept: Population - Population Growth
Chapter: [5.01] Organisms and Populations
[2]10
[2]10.a

Why has the Indian Government set up the organisation named GEAC ? Give any two reasons.

Concept: Ethical Issues
Chapter: [4.02] Biotechnology and Its Application
OR
[2]10.b

Give a schematic representation of the transformation of a pro-insulin into insulin.

Concept: Biotechnological Applications in Medicine
Chapter: [4.02] Biotechnology and Its Application
[2]11

Explain the relationship between B-lymphocytes and T-lymphocytes developing an immune response.

Concept: Concept of Immunity
Chapter: [3.01] Human Health and Diseases
[2]12

“The pyramid of biomass is not always upright.” Explain the statement.

Concept: Ecological Pyramids
Chapter: [5.02] Ecosystem
SECTION - C
[3]13

Draw a T.S. of a young anther of an angiosperm. Label the different layers of the wall and write their functions.

Concept: Pre-fertilisation - Structures and Events - Stamen, Microsporangium and Pollen Grain
Chapter: [1.02] Sexual Reproduction in Flowering Plants
[3]14
[1]14.a

Why should a bacterium be made ‘competent’ ?

Concept: Tools of Recombinant Dna Technology - Competent Host (For Transformation with Recombinant Dna)
Chapter: [4.01] Biotechnology - Principles and Processes
[2]14.b

Explain the role of ‘microinjection’ and ‘gene gun’ in biotechnology

Concept: Tools of Recombinant Dna Technology - Competent Host (For Transformation with Recombinant Dna)
Chapter: [4.01] Biotechnology - Principles and Processes
[3]15

How do desert lizards cope with the variations in their environment ? Explain.

Concept: Organism and Its Environment - Adaptations
Chapter: [5.01] Organisms and Populations
[3]16
[1.5]16.a

Name and explain the mode of action of any two types of IUDs.

Concept: Population Explosion and Birth Control
Chapter: [1.04] Reproductive Health
[1.5]16.b

List the advantges of using ‘Saheli’ as a contraceptive.

Concept: Population Explosion and Birth Control
Chapter: [1.04] Reproductive Health
[3]17
[2]17.a

Write the scientific name of the source plant and the part from which opiods are extracted. What is it commonly and chemically called ?

Concept: Drugs and Alcohol Abuse - Effects of Drug/Alcohol Abuse
Chapter: [3.01] Human Health and Diseases
[1]17.b

Where in the human body are its specific receptors located ? How do opioids affect the human body ?

Concept: Drugs and Alcohol Abuse - Effects of Drug/Alcohol Abuse
Chapter: [3.01] Human Health and Diseases
[3]18
[1.5]18.a

How does the human body respond when vaccine is introduced into it?

Concept: Concept of Immunity
Chapter: [3.01] Human Health and Diseases
[1.5]18.b

It is said that vaccinations are a must for a healthy society. Justify.

Concept: Concept of Immunity
Chapter: [3.01] Human Health and Diseases
[3]19
[3]19.a

What is heterogamety ? Explain the mechanism of sex determinatin in Drosophila.

Concept: Sex Determination - Sex Determination in Humans
Chapter: [2.01] Principles of Inheritance and Variation
OR
[3]19.b

Explain the process of making heterogeneous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes. Where does this process occur in the cell?

Concept: Transcription - Types of RNA and the Process of Transcription
Chapter: [2.02] Molecular Basis of Inheritance
[3]20

Write any six salient features of the human genome as drawn from the human genome project.

Concept: Human Genome Project
Chapter: [2.02] Molecular Basis of Inheritance
[3]21

“Appearance of melanised moths post-industrialisation in England is a classic example of evolution by natural selection.” Explain.

Concept: Evidences for Evolution
Chapter: [2.03] Evolution
[3]22
[3]22.a

Explain any three remedial measures to overcome the acute air pollution in our cities.

Concept: Air Pollution and Its Control - Introduction of Air Pollution and Its Control
Chapter: [5.04] Environmental Issues
OR
[3]22.b

Write any three ways by which noise pollution affects the human body adversely. List any three steps that should be followed in order to reduce noise pollution.

Concept: Noise Pollution and Its Control
Chapter: [5.04] Environmental Issues
[3]23
[1]23.a

What is the primary productivity of an ecosystem and how is it expressed?

Concept: Productivity
Chapter: [5.02] Ecosystem
[2]23.b

Explain what does the equation given below show :
NPP = GPP – R

Concept: Productivity
Chapter: [5.02] Ecosystem
OR
[1]23.c

Name the type of detritus that decomposes faster. List any two factors that enhance the rate of decomposition.

Concept: Decomposition
Chapter: [5.02] Ecosystem
[2]23.d

Write the different steps taken in humification and mineralisation during the process of decomposition.

Concept: Decomposition
Chapter: [5.02] Ecosystem
[3]24
[3]24.a

Write any two biochemical/molecular diagonostic procedures for early detection of viral infection. Explain the principle of any one of them.

Concept: Biotechnological Applications in Medicine
Chapter: [4.02] Biotechnology and Its Application
OR
[3]24.b

Describe the steps that are followed during secondary treatment of sewage.

Concept: Biotechnological Applications in Medicine
Chapter: [4.02] Biotechnology and Its Application
SECTION D
[5]25
[5]25.a

Explain the changes that occur in the ovary and uterus during menstrual cycle in human females. Mention the influence of pituitary and ovarian hormones in bringing these changes.

Concept: Menstrual Cycle
Chapter: [1.03] Human Reproduction
OR
[5]25.b

Compare the characteristic features of insect pollinated and wind pollinated flowers. Explain how the respective features assist in pollination.

Concept: Pre-fertilisation - Structures and Events - Pollination
Chapter: [1.02] Sexual Reproduction in Flowering Plants
[5]26
[1]26.a

Write the specific name of the genus Plasmodium that causes one of the most serious types of diseases in humans. Name the disease.

Concept: Common Diseases in Humans
Chapter: [3.01] Human Health and Diseases
[2]26.b

Describe the events in the life cycle of Plasmodium which take place in the female Anopheles.

Concept: Common Diseases in Humans
Chapter: [3.01] Human Health and Diseases
[2]26.c

Explain what happens in the RBCs of the humans when Plasmodium gains entry into them. How does the human body gets affected?

Concept: Common Diseases in Humans
Chapter: [3.01] Human Health and Diseases
OR
[5]26.d

Explain the interrelationship between organic farming and biofertilizers, with the help of any three suitable examples.

Concept: Microbes as Biofertilisers
Chapter: [3.03] Microbes in Human Welfare
[5]27
[2.5]27.a

How would you find out whether a given tall garden pea plant is homozygous or heterzygous? Substantiate your answer with the help fo Punnett squares.

Concept: Inheritance of One Gene - Introdution of Inheritance of One Gene
Chapter: [2.01] Principles of Inheritance and Variation
[2.5]27.b

Given below are the F2 – phenotypic ratios of two independently carried monohybrid crosses :
(i) 1 : 2 : 1
(ii) 3 : 1
Mention what does each ratio suggest.

Concept: Inheritance of One Gene - Introdution of Inheritance of One Gene
Chapter: [2.01] Principles of Inheritance and Variation
OR
[5]27.c

(a) Why did Hershey and Chase use radioactive 32P and 35S in their experiments? Explain.
(b) Following the experiments conducted by them, write what conclusion did they arrive at and how ?

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

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