CBSE (Science) Class 12CBSE
Account
It's free!

User


Login
Create free account


      Forgot password?
Share
Notifications

View all notifications
Books Shortlist
Your shortlist is empty

Question Paper Solutions - Biology 2011 - 2012 CBSE (Science) Class 12


Marks: 70
[1]1

Mention the unique flowering phenomenon exhibited by Strobilanthus kunthiana (neelakuranaji).

Chapter: [1.01] Reproduction in Organisms
Concept: Modes of Reproduction
[1]2

How does smoking tobacco in human lead to oxygen deficiency in their body?

Chapter: [3.01] Human Health and Diseases
Concept: Drugs and Alcohol Abuse - Adolescence - Drug and Alcohol Abuse
[1]3

A garden pea plant (A) produced inflated yellow pod, and another plant (B) of the same species produced constricted green pods. Identify the dominant traits.

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Elementary Idea of Polygenic Inheritance
[1]4

Why is Eichhornia crassipes nicknamed as “Terror of Bengal”?

Chapter: [5.04] Environmental Issues
Concept: Water Pollution and Its Control - Introduction of Water Pollution and Its Control
[1]5

Write the location and function of the sertoli cells in humans.

Chapter: [1.03] Human Reproduction
Concept: Microscopic Anatomy of Testis
[1]6

Name the following: The semi-dwarf variety of wheat is high-yielding and disease-resistant.

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

Name the following:  Any one inter-specific hybrid mammal.

Chapter: [3.02] Strategies for Enhancement in Food Production
Concept: Introduction of Strategies for Enhancement in Food Production
[1]7

Write the similarity between the wing of a butterfly and the wing of a bat. What do you infer from the above with reference to evolution? 

Chapter: [2.03] Evolution
Concept: Evidences for Evolution
[1]8

Write what do phytophagous insects feed on.

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Interactions
[2]9

Highlight the role of thymus as a lymphoid organ.

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

Name the cells that are released from the above-mentioned gland. Mention how they help in immunity.

Chapter: [3.01] Human Health and Diseases
Concept: Concept of Immunity
[2]10

Why do clown fish and sea anemone pair up? What is this relationship called?

Chapter: [5.01] Organisms and Populations
Concept: Population - Population Interactions
[2]11

Some organisms suspend their metabolic activities to survive in unfavourable conditions. Explain with the help of any four examples.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Post-fertilisation : Structures and Events - Endosperm
[2]12

State the role of DNA ligase in biotechnology.

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

What happens when Meloidegyne incognitia consumes cells with RNAi gene?

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Agriculture
[2]13

Draw a schematic diagram of a part of double stranded dinucleotide DNA chain having all the four nitrogenous bases and showing the correct polarity.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Structure of DNA and RNA
[2]14

Name of parasite the causes filariasis in humans. Mention its two diagnostic symptoms. How is this transmitted to others?

Chapter: [3.01] Human Health and Diseases
Concept: Common Diseases in Humans
[2]15 | Attempt any one of the following
[2]15.1

Name the source of streptokinase. How does this bioreactor molecule function in our body?

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes in Industrial Production
[2]15.2

How do mycorrhizae act as biofertilizers? Explain.

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

Name a genus of fungi that forms a mycorrhizal association with plants.

Chapter: [3.03] Microbes in Human Welfare
Concept: Microbes as Biocontrol Agents
[2]16

State the difference between meiocyte and gamete with respect to chromosome number.

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

Why is a whiptail lizard referred to as parthenogenetic?

Chapter: [1.01] Reproduction in Organisms
Concept: Sexual Reproduction - Fertilisation
[2]17

Explain the work carried out by Cohen and Boyer that contributed immensely in biotechnology.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Principles of Biotechnology
[2]18

Where is sporopollenin present in plants?

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

State the sporopollenin significance with reference to its chemical nature.

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Pre-fertilisation - Structures and Events - Stamen, Microsporangium and Pollen Grain
[3]19 | Attempt any one of the following
[3]19.1

It is established that RNA is the first genetic material. Explain giving three reasons

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Search for Genetic Material - Properties of Genetic Material (DNA Versus RNA)
[3]19.2

Name the enzyme responsible for the transcription of tRNA and the amino acid the initiator tRNA gets linked with.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Transcription - Introduction of Transcription

Explain the role of initiator tRNA in the initiation of protein synthesis.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Transcription - Introduction of Transcription
[3]20

State the theory of Biogenesis. How does Miller’s experiment support this theory?

Chapter: [2.03] Evolution
Concept: Origin of Life
[3]21

Name the two different categories of microbes naturally occurring in sewage water.

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

Explain the role of microbes in cleaning sewage water into usable water.

Chapter: [5.04] Environmental Issues
Concept: Water Pollution and Its Control - Introduction of Water Pollution and Its Control
[3]22

Write the function of the following:- (Oviducal) Fimbriae

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Post-fertilisation : Structures and Events - Embryo

Write the function of the following:- Coleoptile

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Post-fertilisation : Structures and Events - Embryo

Write the function of the following:- Oxytocin

Chapter: [1.02] Sexual Reproduction in Flowering Plants
Concept: Post-fertilisation : Structures and Events - Embryo
[3]23

Name the genes responsible for making Bt cotton plants resistant to bollworm attack. How do such plants attain resistance against bollworm attacks? Explain.

Chapter: [4.02] Biotechnology and Its Application
Concept: Biotechnological Applications in Agriculture
[3]24

Study a part of the life cycle of malarial parasite given below. Answer the questions that follow:

(a) Mention the roles of ‘A’ in the life cycle of the malarial parasite.

(b) Name the event ‘C’ and the organ where this event occurs.

(c) Identify the organ ‘B’ and name the cells being released from it.

Chapter: [3.01] Human Health and Diseases
Concept: Common Diseases in Humans
[3]25

Given below is the representation of amino acid composition not the relevant translated portion of β-chain of haemoglobin, related to the shape of human red blood cells

(a) Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.

(b) What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?

(c) Who are likely to suffer more from the defect related to the gene represented the males, the females or both males and females equally? And why?

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Genetic Disorders - Mendelian Disorders
[3]26

By the end of 2002 the public transport of Delhi switched over to a new fuel. Name the fuel. Why is this fuel considered better? Explain.

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

Draw a schematic sketch of pBR 322 plasmid and label the following in it:

(a) Any two restriction sites.

(b) Ori and rop genes.

(c) An antibiotic resistant gene.

Chapter: [4.01] Biotechnology - Principles and Processes
Concept: Tools of Recombinant Dna Technology - Cloning Vectors
[5]28 | Attempt any one of the following
[5]28.1

Explain the carbon cycle with the help of a simplified model.

Chapter: [5.02] Ecosystem
Concept: Nutrient Cycling
[5]28.2

Explain how does a primary succession start on a bare rock and reach a climax community?

Chapter: [5.02] Ecosystem
Concept: Ecological Succession

Explain how does the algal bloom eventually choke the water body in an industrial area?

Chapter: [5.04] Environmental Issues
Concept: Water Pollution and Its Control - Introduction of Water Pollution and Its Control
[5]29 | Attempt any one of the following
[5]29.1

The following is the illustration of the sequence of ovarian events (a − i) in a human female

(i) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.

(ii) Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.

(iii) Explain the changes that occur in the uterus simultaneously in anticipation.

(iv) Write the difference between ‘c’ and ‘h’.

(v) Draw a labeled sketch of the structure of a human ovum prior to fertilization.

Chapter: [1.03] Human Reproduction
Concept: Gametogenesis
[5]29.2

How does the megaspore mother cell develop into 7-celled, 8 nucleate embryo sac in an angiosperm?

Chapter: [1.03] Human Reproduction
Concept: Embryo Development Upto Blastocyst Formation

Draw a labeled diagram of a mature embryo sac.

Chapter: [1.03] Human Reproduction
Concept: Embryo Development Upto Blastocyst Formation
[5]30 | Attempt any one of the following
[5]30.1

What is the inheritance pattern observed in the size of starch grains and seed shape of Pisum sativum? Workout the monohybrid cross showing the above traits. How does this pattern of inheritance deviate from that of Mendelian law of dominance?

Chapter: [2.01] Principles of Inheritance and Variation
Concept: Deviations from Mendelism - Incomplete Dominance, Co-dominance, Multiple Alleles and Inheritance of Blood Groups, Pleiotropy
[5]30.2

State the aim and describe Messelson and Stahl’s experiment.

Chapter: [2.02] Molecular Basis of Inheritance
Concept: Transcription - Introduction of Transcription
S