PYSP 2006/Class XII
1
BIOLOGY 2006
(Delhi Region)
Time Allowed : 3 hours

Max. Marks: 70
General Instructions :
(i)
All questions are compulsory.
(ii)
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.
(iii)
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.
(iv)
Wherever necessary, the diagrams drawn should be neat and properly labeled.
(v)
Question No. 1-8 are to be answered in one word or one sentence each.
(vi)
Question No. 9-18 are to be answered in approximately 20-30 words each.
(vii)
Question No. 19-27 are to be answered in approximately 30-50 words each.
(viii)
Question No. 28-30 are to be answered in approximately 80-120 words each.
SECTION ‘A’
Q.1
What is the nature of component of bacterial chromosome ?
Ans.
Nucleoid or chromatin body histone protein is absent.
Q.2
Name the disease against which DPT vaccine produces immunity.
Ans.
Dipthesia, Pertursis, Tetanus.
Q.3
What is carcinogen ?
Ans.
Cancer causing agent are called carcinogens.
Q.4
Approximately how many years ago did the first life on earth originate.
Ans.
800 millions years ago
Q.5
Expand the term TLC, DLC.
Ans.
TLC = Total Leucocyte Count
DLC = Differential Leucocyte Count
Q.6
Which technique can be used for improved varieties of rose ?
Ans.
Bud grafting
Q.7
Name two basic processes involved in sexual reproduction
Ans.
There are gametogenesis & syngamy.
Q.8
E – Wartes are referred to
Ans.
(i)
radioactive waste
(ii)
nuclear waste
(iii)
can be both (i) & (ii)
(iv)
electronic waste
(iv)
Electronic waste
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PYSP 2006/Class XII
2
SECTION ‘B’
Q.9
What advantage does the sea anemone get in the sea anemone-hermit crab facultative mutualism?
Given an alternative term for this kind of mutualism.
Ans.
In the facultative mutualism, sea anemone rests on the back of Hermit crab and captures food in the
form of fishes & insects. It is also referred to as commensalisms.
Q.10
In a wheat field, some broad-leaved weeds were found by a farmer. Which phytohormone can be used
to eradicate them?
Ans.
2, 4-D and 2, 4, 5-T are the weeds that act as Weedicides.
Q.11
Correct the statement given below with respect to brazzein : “Brazzein is a high colorie carbohydrate”.
Ans.
Brazzein is a low calorie carbohydrate with more protein.
Q.12
How is polyspermy prevented in humans ?
Ans.
It is prevented with the help of sperm lysins like hyaluronic acid that surrounds the wall of sperms and
kills them.
Q.13
Write the full form of ELISA ? Give an example of the clinical application of ELISA test.
Ans.
ELISA stands for „Enzyme Linked Immonosorbant Assay‟. It is ammuno-chemical test. This bio-medical
diagnostic test is performed for the detection of Aids, HIV and Cancer.
Q.14
What is Translocation & Duplication in regard to chromosome.
Ans.
If exchange of gametic material takes place between non sister.
OR
Define ageing ?
Ans.
Gradual and slow deterioration of body cells, tissue and patch leading to inactivity of an organism and
ultimate death.
Q.15
What is common in Nepenther, Utricularia and Drosera in regard to special mode of Nutrition ?
Ans.
All the three plants are insectivorous in their mode of nutrition they desire (Obtain) N 2 from animal
protein i.e. insects.
Q.16
What is nitrification ?
Ans.
Oxidation of NH3 by bacteria producing NO2
Q.17
Name the hormone which induces Milk Secretion ?
Ans.
1. Prolactien or Leuteotropic hormone. (L.H.) It secret from the Posterior lobe of the Pituitary gland.
Q.18
Who finally proved that life can originate from pre-existing life. Name the experiment.
Ans.
(i)
Louis Pasteur
(ii)
Name of experiment is longneck flarte experiment.
–1
(Nitrates).
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PYSP 2006/Class XII
3
SECTION ‘C’
Q.19
Draw a diagrammatic sketch of the microscopic view of a mammalian sperm and label any four parts in
it.
Ans.
For labeled diagram of sperm :
Plasma
membrane
Acrosome
Nucleus containing
chromosomal material
Head
Neck
Middle piece
Mitochondria
(energy source for swimming)
Tail
Structure of a Sperm
20.
What would happen to the successive trophic levels in the pyramid of energy if the rate of reproduction
of phytoplankton was slowed down ? Suggest two factors which could cause such a reduction in
phytoplankton reproduction.
Ans.
When reproduction of phytoplanktons is slowed down, being producer level, the successive levels of
food pyramids will get energy. Top most levels may even perish for want of energy. Factors responsible
for reduction in reproduction of phytoplanktons are oxygen concentration (BOD) in water and water
pollution by pesticides & other chemicals.
Q.21
What is cryopreservation ? Give its one use.
Ans.
Cryos means freezing or very low temperature condition preservation the things under very low
temperature or freezing condition preservation of body organs before grafting or transfusing like blood,
cornea of eye, kidney of body organs before grafting or transfusing like blood, cornea of eye, kidney etc.
Q.22
What is dagamospermy ? How is agamospermy different from parthenogenesis and parthenocarpy?
Ans.
Agamospermy – Agamo – means without sperms or seeds. It is a special mode of reproduction in
plants. Some times a diploid embryo sac is developed from diploid spore mother cell. It is developed
parthenogenetically. In parthenocarpy or parthenogenesis unfertilized haploid ovary is developed in to
an individual .
Q.23
Ans.
(i)
How can haploid plants be raised in the laboratory ?
(ii)
Name the plant first used in India to produce haploid plants.
(iii)
Can haploid plants raise their own progeny ? Give reason.
(i)
Haploid means having „x‟ or „n‟ no. of chromosomes (even number) in a cell. Haploid is also
called pollen grain.
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PYSP 2006/Class XII
(ii)
4
Culture, wheat, rice, maize, rubber plants are produced by developing embryoids from their
anthers.
(iii)
Haploid varieties of these plants are superior to then parental plants but such plants can not raise
their progeny.
Q.24.
Name the explain any three adaptations of mangrove to the following conditions prevailing in the
Sunderbans (West Bengal).
Ans.
Mangroves of Sunderbans of West Bengal have undergone following adaptations :
(i)
Change in skin colour due to temperature.
(ii)
Change in the slope of mouth and face.
(iii)
Change in the shape size of tail.
(v)
Tolerance limit.
Q.25
Define senescence. Explain the „programmed senescence theory‟ of ageing.
Ans.
Senescence is programmed changes in the structure of cells and then function in the body of an
organism (plant, animal or human being) programmed theory of ageing is
(i)
Morphological and physiological changes in the body organs.
(ii)
Decline in the reproductivity.
(iii)
Cellular changes – Decreases in Mitochondria – number in activity in the protoplasm of the cell.
(iv)
Accumulation of polysaccharides, calcium, lactic acid in the body organs.
(v)
Weak eye sight and hearing capacity.
(vi)
Stuffness of joints, formation of permanent cells.
(vii)
Weak nervous & muscular system.
(viii)
Weak digestive & absorptive system.
(ix)
Loss of regeneration.
(x)
Loss of body hair.
Q.26
What are Carcinogens ? Give example why disease caused by them is so dread ?
Ans.
Cancer causing agent care called carcinogens. Two examples are :
1.
Tobacco Tar and Benze Plyrene.
2.
Radiactive rays.
Cancer the diseased caused by them is dreaded in Crecerable and fatal.
OR
Giive an account of the three drawbacks in the use of chemical fertilizer.
Ans.
27.
The drawbacks of using chemical fertilizers.
(a)
The fertilizers applied to the crop are lost to the surface run off and pollutes the soil and water
resources.
(b)
These chemicals post a danger to the activity of soil microbes.
(c)
They either make the soil alkaline or acidic & subsequently unfit for the growth of crops.
Draw a labeled diagrams of L.S. Pistil (Carpel).
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PYSP 2006/Class XII
5
Ans.
Pollen tube
Antipodal
Polar nuclei
Egg cell
Synergid
Longitudinal section of a flower
showing growth of pollen tube
L.S. Pistil showing path of pollen tube growth
Q.28
Draw a labeled diagram for Asexual reproduction in the following:
(i)
Budding yeast
(ii)
Binary fission in Amoeba
Ans.
Nucleus
Daughter cell
Bud
Nucleus
Daughter cells
(b)
Parent cell
(a)
Mother cell
Cell division in unicellular organism : (a) Budding in yeast;
(b)Binary fission in Amoeba
OR
Discuss the causes and effects of global warming. What measures need to be taken to control global
warming ?
Ans.
Causes of global warming :
(a)
Increase use of fossil fuels and burning of toxic materials.
(b)
Afforestation.
(c)
Increase in human population these by leading to deforestation.
(d)
Increase in emission of green house gases in to the atmosphere
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PYSP 2006/Class XII
6
Effects of global warming :
(a)
Rise in temperature leading to deleterious changes in the environment.
(b)
Result in odd climatic changes.
(c)
Lead to increased melting of polarize caps as well as of other places like the Himalayan snow
caps.
(d)
Rise in sea level that can submerge many coastal areas.
Measures to control global warming ?
Q.29
(a)
Cutting down of fossil fuels.
(b)
Improving efficiency of energy usage, reducing deforestation.
(c)
Planting trees.
(d)
Slowing down the growth of human population.
(e)
Reduction of emission of green house gases into the atmosphere.
How did Hershey and Chase differentiate between DNA and Protein in their experiment while proving
that DNA is the genetic material ?
Ans.
Assessments by Vriti
PYSP 2006/Class XII
7
Hershey and Chase (1952) conducted their experiment on T2 phase which attacks the bacterium E.coli.
35
32
The phage particles were prepared by using radioisotopes of S and P.
In the phage particles with radioactive protein, the bacterial pallets have almost nil radioactivity
indicating that protein have failed to migrate into bacterial all. So it was concluded that DNA must have
entered the bacteria.
OR
Using a Punnett square workout the distribution of a phenotypic features in the first filial
generation after a cross between a homozygous female and a heterozygous male for a single
locus.
Ans.
A Punnett square used to understand a typical monohybrid cross conducted by
Mendel between true-breeding tall plants and true-breeding dwarf plants
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PYSP 2006/Class XII
8
From the Punnett square it can be seen that 1/4 th of the random fertilization lead to TT, ½ lead to Tt
and 1/4 th to tt. Though the F1 have a genotype of Tt, but the phenotype character seen is tall. At F 3, ¾
th of the plants are tall. Where some of them are TT while others are Tt, within the genophytic pair Tt
only are character „T‟ tall is expressed. Hence the character „T‟ or tall is said to dominant over the allele
„t‟ or dwarf character Tt is thus due to this dominance of the character over the other that all the F 1, are
th
tall of F2 – 3/4 of the plant are tall.
Q.30
Describes the Replication of Retrovirus by the draw.
Ans.
Retrovirus
Viral DNA core
Virus infects
normal cell
Viral protein
coat
Animal cell
Plasma
membrane
Viral RNA is introduced into cell
Viral DNA is
produced
by reverse
transcriptase
Cytoplasm
Viral DNA incorporates
into host genome
New viral RNA
is produced by
the infected cell
New viruses
are produced
DNA
Nucleus
New viruses
can infect other cells
Note: Infected Cell can survive while viruses
are being replicated and released
Replication of retrovirus
Define the term expanded form :
Ans.
(i)
RCH
(ii)
ET
(iii)
AIDS
(iv)
IUDS
(v)
ZIFT
(i)
RCH : Reproductive and Child Health care programmes
(ii)
ET : Embryo Transfer Technique
(iii)
AIDS : Acquired Immuno Deficiency Syndrome.
(iv)
IUDS: Intra Uterine Devices
(v)
ZIFT: Zygote Intra Fallopian Transfer.
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