HOLIDAY HOMEWORK CLASS XII BIOLOGY

HOLIDAY HOMEWORK
CLASS XII
BIOLOGY
A. SAMPLE PAPER
GENERAL INSTRUCTIONS:
1. All questions are compulsory.
2. This question paper consists of four sections A,B,C and D. Section A contains 8 questions
of 1 mark each, section 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 such questions.
4. Wherever necessary , the diagrams drawn should be neat
and properly labelled.
SECTION –A
1.
2.
3.
4.
5.
6.
7.
8.
Offsprings derived by asexual reproduction are called clones. Justify giving two
reasons.
A bilobed , dithecous anther has 100 microspore mother cells in a
microsporangium. How many male gametophytes this microsprangium can
produce?
Name any two vertebrate body parts that are homologous to human forelimbs.
1
Name the disorder with the following chromosome compliments:
(a)
22pairs of autosomes + XXY
(b)
22pairs ofautosomes + XO
What do you understand by flocs?
Name the nematode that infects the roots of tobacco plant.
Define brood parasitism.
Name any two metals which are used as catalyst in catalytic converter.
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SECTION-B
9.
10.
11.
12.
13.
14.
What is meant by “Hot Spots” in biodiversity? Name two hotspots of India.
(a) What are the ecosystem sevices?
(b) who attempted to put price tag on ecosystem
Services?
OR
List any four possibilities that help the living organisms cope with the various
situations.
Draw a well labelled diagram of an antibody molecule.
Do you think that friends can influence one to take alcohol/drugs? How can you
protect yourself from such influence?
Fill in the blank spaes 1,2,3, and 4 from the table given below.
Type of microbe scientific name commercialproduct
Yeast
1------------------ ethanol
2-----------lactobacillus
lactic acid
Bacterium
acetobacter
3---------------Fungus
4--------------citric acid
Define plant breeding. Name any two characters that breeders have tried to
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2
2
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2
15.
16.
17.
18.
incorporate to crop plants.
Expand the following abbreviations:
(a)
MALT
(b)NACO (c) HIV
2
(d) CMI
If a double stranded DNA has 20% of cytosine calculate the percent of adenine,
guanine and thymine.
Coconut palm is monoecious while date palm is dioecious. Why are they called
so?
(a) Expand IUD.
(b) Why is CuT considered a good contraceptive to space children.
2
2
2
SECTION-C
19.
20.
21.
22.
23.
24.
25.
With the help of labelled diagrams, depict the stages of a megaspore maturing
into a embryosac.
Answer the following questions based on Meselson and Stahl’s experiment :
(a)Write the name of chemicalsubstance used as a source of nitrogen in the
experiment by them.
(b)how did the scientists make it possible to distinguish the heavy DNA molecue
from the light DNA molecule? Explain.
(c)write the conclusion the scientists arrived at after completing the experiment.
A segment of DNA-3’-TTCACGGGGATG-5’ was translated into an oligopeptide
lysine-serine-proline-tyrosine in the respective sequence.
(i)
Write the codons for lysine and proline aminoacids.
(ii) If the second cytosine in the DNA segment is
substituted by thymine ,what will be the
sequence of aminoacids in the new
oligopeptide?
(iii) Write the anticodons for lysine and proline
aminoacids.
“A population has been exhibiting genetic equilibrium” . Answer the following
with regard to the above statement.
(i)
Explain the above statement.
(ii) Name the underlying principle.
(iii) List any two factors which would upset the
genetic equilibrium of the population.
OR
Stanley Miller performed an experiment by creating in the lab the probable
conditions of the atmosphere of the primitive earth.
(i) Whatwas the purpose of the experiment.
(ii)In what form was the energy supplied for the
chemical reaction to occur?
(iii)Give a diagrammatic representation of Miller’s
experiment.
(a)In case of Bt cotton, how does the toxic insecticide protein produced by the
bacterium kill the insect pest but not the cell of Bacillus thuringiensis where the
toxic protein is generated?
(b)What do you mean by cry and Cry?
How is a host cell made competent in introducing recombinant DNA? (any 3
methods)
Explain the importance of (a) ori (b)ampR (c) rop in the E.coli pBr322 vector .
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26.
3
Forest fire
27.
Plants
respiration
burning fossil fuels
The above diagram shows a simplied biogeochemical cycle.
(i)Name the compound whose cycle is depicted.
(ii)What adverse effect does its excess have on the
Environment?
(iii) Suggest two ways of reducing this effect.
Draw a diagrammatic representation to depict the multiplication of an HIV virus
in a host cell.
3
SECTION –D
28.
29.
30.
(a)Mention the arrangement of different genes that in bacteria is reffered to as
lac-operon.
(b) Draw a schematic labelled illustration lac operon in a switched on state.
(c)Describe the role of lactose in lac operon.
OR
(a)A true breeding homozygous pea plant with green pods and axial flowers as
dominant characters ,is crossed with a recessive homozygous pea plant with
yellow pods and terminal flowers. Work out the cross up to F2 generation giving
the phenotypic ratios of F1 and F2 generation respectively.
(b)State the mendelian principle which can be derived from such a cross and not
from monohybrid cross.
(a)Describe the stages of oogenesis in human females.
(b)Draw a labelled diagram of a human ovum released after ovulation.
OR
(a)When and where does spermatogenesis occur in a human male.
(b)Draw a diagam of a mature human male gamete. Label the following parts:
acrosome, nucleus, middle piece and tail.
(c)Mention the function of acrosome and middlepiece.
(a) Describe “The Evil Quartet” of biodiversity loss.
(b)Differentiate between in situ and ex situ approaches of conserving
biodiversity.(any two points)
OR
Define the following:
(a)
E-waste
(b)
Electrostatic precipitator
(c)
Scrubber
(d)
Eutrophication
(e)
Ozone hole
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