Download BIOLOGY (THEORY) – 2008

PYSP 2007/Class XII
1
BIOLOGY 2007
(Delhi Region)
Time Allowed : 3 hours

Max. Marks: 70
General Instructions :
1.
All questions are compulsory.
2.
The question paper consists of four sections, A, B, C and D. Sections A contains 8 questions of 1 mark
each. Sections B is of 10 questions of 2 marks each, Section C has 9 questions of 3 marks each whereas
Section D is of 3 questions of 5 marks each.
3.
There is no overall choice. However, an internal choice has been provided in one question of 2 marks,
one question of 3 marks and all the three questions of 5 marks weightage. A student has to attempt only
one of the alternatives in all such questions.
4.
Wherever necessary, the diagrams drawn should be neat and properly labeled.
5.
Question No. 1-8 are to be answered in one word or one sentence each.
6.
Question No. 9-18 are to be answered in approximately 20-30 words each.
7.
Question No. 19-27 are to be answered in approximately 30-50 words each.
8.
Question No. 28-30 are to be answered in approximately 80-120 words each.
SECTION ‘A’
Q.1
Mention the scientific term used for modified form of reproduction in which seeds are formed without
fusion of gametes.
Ans.
The scientific term used for modified form of reproduction in which seeds are formed with fusion of
gametes (fertilization) is apomixes.
Q.2.
What does ecological niche of an organism represent ?
Ans.
The habitate together with function of a species is called niche or ecological niche.
Q.3.
It was diagnosed by a specialist that the immune system of the body of a patient has been suppressed.
Name the disease the patient has been suffering from and its causative agent.
Ans.
The patient has been suffering from AIDS (Acquired Immuno Deficiency Syndrome). The causative
agent of the disease is HIV-III (a virus)
Q.4
Name the disease characterized by the inflammation of joints.
Ans.
Ortho orthrites.
Q.5
Rearrange the following level in their correct organization sequence.
Ecosystem, Population, Biosphere.
Ans.
Organism  Species  Population  Community  Ecosystem  Landscape  Biosphere.
Q.6
Who suggested inborn errors in metabolism ?
Ans.
Archibold Garrod
Q.7
Write the biochemical reaction of yeast fermentation of molaxes for Alcohol Production.
Ans.
C6 H12O6
Zymare
(from yeast)
2C2 H5OH 2CO2
Expand IPM and VAM.
Ans.
IPM = Integrated Pest Management.
VAM = Vascular Arbuscular Mycorrhiza
Q.8
The first Transgenic crop was
1. Pea
Ans.
2. Tobacco
3. Flax
4. Cotton
Tobacco
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Landscape, Organism,
PYSP 2007/Class XII
2
SECTION ‘B’
Q.9
Explain the significance of the auxin / cytokinin ratio in plant tissue culture.
Ans.
According to Skoog & Miller. There should be auxins / cytokinin in ratio as growth regulator i.e. 2-4%.
They take part in shot in root formation and also cellus formation. Without growth hormones, poor
growth occurs in plant tissue culture.
Q.10
What does S-shaped pattern of population growth represent ? How is J-shaped pattern different form it
and why?
Ans.
In the sigmoid form of S-shaped form of growth the population in a favourable area, initially increases
slowly, then multiply or reproduce rapidly and finally slows down gradually due to carrying capacity
which provide environmental resistance. Yeast cells & Human population show S-shaped (sigmoid)
curve.
In J-shaped curve only two phases are there i.e. lag phases & exponental phase.
Q.11
What does secondary productivity in an ecosystem indicate ? List any two factors by which productivity
is limited in aquatic ecosystems.
Ans.
The Heterotrophic organisms obtain there energy by consuming organic matter from consumer. In such
organisms if there is more storage than consumption, the biomass of a population would be higher at
the end of a time period than at the beginning.
The rate of increase in the biomass of heterotrophs per unit time area is called secondary productivity.
Secondary productivity is generally limited by high and nutrients.
Q.12
How do viruses enter plant body and spread to long distances within it? Mention any two ways by which
viruses spread from one plant to another.
Ans.
Pathogene virus enter the plant body through diseased parts of plant or through diseased plant as a
whole (entire plant). These may also enter through secondary host and wild plants. They may enter
through soil (absorbed with wrote or through diseased seeds). So through eradication of diseased parts
or entire plant or secondary hosts, viral disease can be prevented.
Q.13
What is vernalisation? How is the process of vernalisation advantageous to plants ?
Ans.
Treatment of seeds or sapling at freezing part very low temperature condition to obtain desired modified
characters is called vernalisation. Of results in early seed germination and early flowering of plants.
Q.14
Write two examples of developmental evidence for evolution from plant kingdom ?
Ans.
(i)
Bryophytes are both aquatic & terrestrial with swimming sperms (Amphibious of plant kingdom).
(ii)
Pteridophytes are the intermediate stage between Bryophytes and Supermatophytes Chaving
developed vascular system.
OR
A particular techniques helps to diagnose chromosomal disorder in an unborn foetus, what is the name
of this techniques and how is it performed ?
Ans.
The name of technique is Ammocan testis. It is performed by examining the cells of Amniotic fluid.
Q.15
What is transgenics ?
Ans.
An organism which becomes genetically transformed by introducing a new DNA sequence into its
genome is called a transgenic organism (GMO) The transgenic crops are also called genetically
modified crops or GM crops. For example Bt cotton. It is a transgenic variety of cotton which contains a
foreign gene from Bacillus thuringiensis bacterium. But cotton has become insect resistant due to this
modification.
Q.16
Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do
you know any other plant that bears unisexual flowers.
Ans.
Students are advised to do it theselves with the help of their teacher corn, papaya produce unisexual
flowers.
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PYSP 2007/Class XII
3
Q.17
Define the term Transcription.
Ans.
It is a process of copying genetic information from one strand of the DNA in to RNA is termed as
transcription.
Q.18
Define Biotechnology.
Ans.
Biotechnology is the controlled use of biological agents, such as micro-organism or cellular components
like enzymes for the benefit of organisms.
SECTION ‘C’
Q.19
Describe the polygonum type of embryo sac. Why it is generally referred to as monosporic?
Ans.
In polygonum embryonic sac, villi are present in the form of belt or girdle. Over the chlorine e.g. dogs,
cats and rates placenta is erosion of uterine epithelium. In this four layers are present.
Q.20
What is obsessive-compulsive disorder ? How is it different form borderline personality disorder ? What
are the two most common obsessions that affect adolescents ?
Ans.
It is a disorder of cerebral functions which is characterized by the convulsions and person becomes
unconsciousness where as Border line personality disorder (BPD) is an emotionally unstable
personality disorder.
It is characterized by unpredictable moods, outbursts of emotions quarrel-some behaivour and conflicts
with others. They are highly reactive and suffer from depression, anxiety and irritability.
Q.21
What are second generation vaccines ?
Ans.
With the help of genetic engineering vaccines of immense importance are synthesized, called second
generation vaccines. These consist of a few antigen present on the surface of the infecting agents rather
than the whole inactivated organism (first generation vaccine). The surface antigens are produced in
large quantities with the help of recombinant DNA technique. These are injected in safer dozes to
healthy individuals for development of immunity. These are more uniform in quality and have less side
effects than first generation vaccines. For examine, vaccine for Hepatitis-B.
Q.22
What are cDNA libraries? How they are made ?
Ans.
A complete library of genome fagments is a set of independent clones, that contains the entire genome
among the recombinant DNA molecules. Genonomic libraries are also called gene hanks. Construction
of cDNA library involves following steps:
(i)
the generation of DNA segments,
(ii)
introduction of DNA fragments into a cloning vector like plasmid, cosmid or virus.
(iii)
introduction of cloned DNA into a bacterium like E.coli.
Q.23
What are steroids ?
Ans.
Steroids are complex crystallisable lipids of high molecular might, with a core structure of one-carbon
ring and three 6-carbon rings. They are present in plants as well as in animals. Several micro-organisms
like fungi, bacteria, actinomycetes, yeasts.
OR
Do eukaryotic cells have restriction endonucleases ? Justify your answer.
Ans.
Restriction enzymes restrict the infection of bacteria by some viruses like bacteriophages by degrading
the viral DNA without affecting viral DNA. These are present in some bacterias.
Eykaryotic cells do not have restriction endonucleases.
Q.24
State the relationship between biotic potential and environmental resistance.
Ans.
The inherent maximum capacity of an organism to reproduce or increase in number is called biotic
potential.
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PYSP 2007/Class XII
4
Where as the factors which do not allow all the organism of a population to reproduce together
constitute the environmental resistance. Both are contradictory.
Q.25
Pertaining to the process of ageing mention three major steps show the free radicals in the body lead to
progressive decline in the functioning of cells.
Ans.
During ageing, the brain loses some cells and others (neurons) are damaged. There is a decline in the
muscle mass. Moreover Programmed senescence theory, ageing is the result of sequential switching
on and off of certain genes causing programmed cell death or apotosis. The number of mitochondria in
the cells decreases.
Q.26
Describe the structure of immunoglobin (Ig) antibody. Draw a diagram showing the formation of antigen
antibody complex and label the parts.
Ans.
The protective chemicals produced by the body in response to antigens are know as antibodies.
Antibodies are a class of proteins called Immunoglobulin (Igs). They are complex proteins.
Antigen
Antibodies
Antigen-Antibody Reaction
Antigen – Antibody Reaction
Q.27
Draw a labeled structured of Human (Male) sperm.
Ans.
Plasma
membrane
Acrosome
Nucleus containing
chromosomal material
Head
Neck
Middle piece
Mitochondria
(energy source for swimming)
Tail
Structure of a Sperm
Q.28
Outline salient features of carbon cycling in an ecosystem.
Ans.
In the biosphere the major reservoirs of carbon are atmosphere, ocean and fossil fuels. Carbon
availability is a crucial factor in the maintenance of plants and animals. The main features of carbon
cycle are as follows: Carbon in the form of carbon dioxide is drawn from the biosphere by various
activities like
(i)
Photosynthesis by green plants, around 7 × 0
(ii)
By corals for making calcareous skeletons.
13
kg carbon is fixed by producers annually, and
Carbon is added to the biosphere by
(i)
Respiration in organisms
(ii)
Decay of organic wastes and dead organisms,
(iii)
Burning of fuel
(iv)
Weathering of rocks and
(v)
By volcanic activities. Carbon cycle can be thoroughly understood by following representation:
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PYSP 2007/Class XII
5
OR
List of briefly describe any three diagnostic technique by in ages based on the use of X-rays.
Ans.
(i)
C.T. Scan (Computed Tomography Scanning): It is a radio logic technique which combines with
use of X-rays with computer technology to obtain 2 or 3 dimensional image which is cross
sanctioned.
(ii)
MRI (Magnetic Resonance Imaging): It is also called NMR (Nuclear Magnetic Resonance)
spectroscopy. Here no radiation like X-rays are used. This technique also given 3 dimensional
images and is based on the principle than when H2 atoms of water and radio waves. H atoms
release protons.
(iii)
Barium X-ray examination: Working on the application of X-rays. It is useful in detecting the
disorders of digestive-track.
Q.29
Why is it generally difficult to transplant organs from one person to an other? How is the difficulty now
over come?
Ans.
In the technique of organ transplant lateral corneal transplantation has been successfully done. But
organ like kidney heart & lever it is difficult, it is because different blood supply and immune system of
the reciepient and donor. But now by the process of Cryogeneses (preserving organs under freezing
conditions) it is possible. The difficulty can be overcome by this.
OR
What is co-dominance ? How does it differ from in complete dominance?
Ans.
When trogenes in a pauses equally dominant separately express. Themselves e.v. Blood groups is man
is an example of codominance.
In the pair of two alleles as in Mirabilis galapa,
dominance.
a ratio 1 : 2 : 1 is obtained which shows incomplete
Q.30
Why is the process of fertilization in a flowering plant referred to as double fertilization?
Ans.
Fertilization in flowering plant is referred to as double fertilization because two male gametes from the
same microscope takes part in fusion.
Functions of flower as follows:(i)
Lowers are modified to perform the function of sexual reproduction.
(ii)
They are shaped variously to help in pollination.
(iii)
They provide seat for germination of pollen, development of pollen tube formation of gametes and
fertilization.
(iv)
Some floral parts help in dispersal of fruits and seeds.
(v)
The ovary transforms into fruit and ovules into seeds after fertilization in flowers.
OR
What is the gene therapy ? Illustrate using the example of adenosine deaminase (ADA) deficiency ?
Ans.
Treatment of a genetic disorder by manipulating genes is called gene therapy. It is the collection of
methods that allows correction of a genetic defect which is deaminase in a child or a embryo. For
example enzyme adenosine deaminase (ADA) is very critical for immune system to function. The
deficiency of ADA causes severe combined immuno deficiency disease (SCID). The patient lacks
function T-lymphocytes and fails to fight the infections pathogens. Using the gene therapy lymphocytes
are extracted from the patients done mallgou and a normal functional gene for ADA is introduced into
these lymphocytes with the help of retrovirus. These cells are introduced into the patients bone marrow.
There lymphocytes contain the functional ADA gene and reactivate the patients immune system.
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