VEDA VYASA D . A .V . PUBLIC SCHOOL
CLASS XII
BIOLOGY
Time : 3 Hrs
MM: 70
General Instructions :
(i) All questions are compulsory.
(ii) This question paper consists of four Sections A, B, C and D. Section A contains 8
questions of one mark each, Section B is of 10 questions of two marks each, Section
C is of 9 questions of three marks each and Section D is of 3 questions of five 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 such questions.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
SECTION A
1. A son has blood group O. What is true of the inheritance of this blood group in his case?
(a) His mother should be with AB blood group.
(b) Both his parents should be heterozygous A group.
(c) His father could be homozygous B group.
(d) His mother could be homozygous A group
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2.If a double stranded DNA has 40% guanine calculate the % of adenine in the DNA.
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3. How do zoological parks differ from National park concerned with species conservation?
4. What is Primer? What is its role in PCR?
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5. In Griffith’s experiment, how did the non virulent strain of Streptococcus Pneumoniae
become virulent?
6. Differentiate between gaseous and sedimentary cycles.
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7.. What is allergy? Name the antibody responsible for it.
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8.Which stage is common between hydrarch and xerarch succession?
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SECTION B
9. What type of population interaction is shown in A,B,C, D between the species A and B as per
the tabular column given below.
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10 Polar regions are usually inhabited by large sized animals. Small sized animals are
generally rare. What is the disadvantage of being small in polar regions?
11 Five species of warblers co-existed on a tree without any sort of competition
How did they avoid competition?
12. Label A, B, C and D in the given diagram
13. The following is the diagrammatic representation of decomposition cycle in a terrestrial
ecosystem, answer and complete the cycle.
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2
.2
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14. What do you mean by SNPs and its significance with respect to human genome?
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15.Night blindness and colour blindness is usually seen in human males? Can human female also
develop this disorder? Explain it
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16..In terrestrial ecosystem DFC and GFC are interlinked at certain level. Jusify the
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statement
17. In a simple ecosystem, there exists a field of clover. Mice eat the clover and
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skunks eat the mice. The skunks are in turn eaten by wolves. If 10,000 calories are
available from clover plants, how much energy would each of the organism in the
food chain receive.
18. In the pyramid of biomass drawn name the two crops.
(i) One which is supported.
(ii) One which supports.
(iii) In which ecosystem is such a pyramid found.
OR
. Biofortification can solve the problems of hidden hunger to a large extent. Prove it.
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SECTION C
19.(i) From the graph of species richness and area relationship write the equation for‘A’and ‘B’.
(ii) How is biodiversity useful to modern agriculture ?
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20 (i)Mass extinction of species has been witnessed even before humans appeared
on the earth . But how is the sixth extinction presently in progress different
from the previous episodes?
(ii) Mention any two consequences of such an extinction.
21 (i)
Water
Zooplanktons
Small fish
Fish eating birds
DDT
(0.003ppm)
(0.04ppm)
(0.5ppm)
(5ppm)
Why is the concentration of DDT increasing from the producers to consumers in the
above food chain?
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(ii) How do foam and ecosan help in waste water treatment?
22 Differentiate inbreeding and out breeding. What type of danger is associated with
inbreeding? Name two animal breeds which are developed by cross breeding.
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23 Complete the following
(i) The pathogens which are transformed to make them non virulent are called
________pathogens.
(ii) To isolate DNA from fungus cells, the later are treated with _________.
(iii) The culture system where in the used medium is drained out from one side , while fresh
medium is added from the other is called _________.
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24.(i) A person suffering from Elephantiasis has an abnormally increased swelling in his lower
limbs. What could be the reason for the swelling?
(ii) Master X has the habit of taking pain killers for mild headache. He is advised not to take
painkillers frequently by his family doctor. What could be the probable reason
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25. Classify the following under the four types of barriers in innate immunity.
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1. Interferons
2. P M N L neutrophils
3. Saliva in mouth
4. Acid in Stomach
5. Mucous coating in Windpipe
6. Natural killer cells
26. (a) Draw a longitudinal sectional view of a typical anatropous ovule to show the site where
double-fertilization takes place. Label any four major parts of the ovule.
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OR
Draw a neat labelled diagram of transverse section of an anther
2 7You have been deputed by your school principal to train local villagers in the use of biogas
plant. With the help of a labelled sketch explain the various parts of the biogas plant.
3.
SECTION D
28.Observe the following diagram and answer the questions at the end
a. Name the gases.
b. Comment on the consequences of increase in the level of each gas (any three)
OR
The figure below shows an ozone hole which develops over Antartica every year between late
August and early October.
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(a) If ozone gas is continuously formed by the action of UV rays on molecular oxygen , then
why are we worried about ozone depletion ?
(b) What are the units for measuring the thickness of ozone ?
(c) How is an ozone hole formed and what are its harmful effects?
(d) What efforts are being taken at the international level to prevent ozone hole formation?
29. (A) what is the number of chromosomes in the following cells of a human male?
(a) Sertoli cells (b) Spermatogonial cells.
(B) Mention the function of leydig cells.
(C) Draw diagrams of T.S of testis and explain the process of spermatogenesis
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OR
( a) What is Amniocentesis?
(b) Name the hormones influencing
(1) Ovulation
(2) Development of corpus Luteum
(c ) Draw well Labeled diagram of female reproductive system in human being.
30. Explain the Lac Operon System with the help of a neat labelled diagram.
OR
Explain DNA finger printing process with diagram
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