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Published on: 25/10/2025
Download CBSE Class 12th Standard CBSE Biology question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 12th Standard CBSE Biology
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1.
2.
The DNA fragments produced by the use of restriction endonucleases can be separated by
polymerase chain reaction
gel electrophoresis
density gradient centrifugation
any of the above.
3.
Biolistics (gene gun) is suitable for
introducing rDNA into plant cells
introducing rDNA into animal cells
disarming the pathogen vectors
DNA fingerprinting.
4.
Pyamid of energy in a river ecosystem is
always upright
always erect
constant
declining
5.
The '10 per cent law' is related to
Mendelian genetics
non-mendelian genetics
energy transfer from lower trophic level to higher trophic level
energy consumption during photosynthesis in C4 plants
6.
Identify which one of the following is an example of incomplete ecosystem?
grassland
cave
river
wetland
7.
Which one of the following ecosystem types has the highest annual net primary productivity?
tropical deciduous forest
temperate evergreen forest
temperate deciduous forest
tropical rain forest
8.
Given is one of the types of ecological pyramids. This type represents
pyramid of numbers in a grassland
pyramid of biomass in a fallow land
pyramid of biomass in a lake
energy pyramid in a spring
9.
Which of the following is expected to have the highest value (gm/m2/yr) in a grassland ecosystem?
Tertiary production
Gross production
Net production
Secondary production
10.
The restriction enzyme(s) used in recombinant DNA technology that make staggered cuts in DNA leaving sticky ends is/are
Eco R I
Hind III
Bam H I
all of these
11.
Restriction enzyme Eco RI cuts the DNA between bases G and A only when sequence in DNA is
GATATC
GAATTC
GATTCC
GAACTT
12.
Biolistics (gene-gun) is suitable for
disarming pathogen vectors
transformations of plant cells
constructing recombinant DNA by joining with vectors
DNA fingerprinting
13.
What will be the correct gene expression pathway?
gene -> mRNA -> transcription - translation - protein
transcription - gene - translation - mRNA - protein
gene - transcription - mRNA - translation - protein
gene - translation -mRNA - transcription -protein
14.
Restriction anzymes
restrict elongation of DNA
cut DNA at specific locations
link tagether two pieces of DNA
restrict DNA replication
15.
Which one of the following pallindromic base sequences in DNA can be easily cut at about the middle by some particular restriction enzyme.
5' CACGTA 3' ; 3' CTCAGT 5'
5' CGTTCG 3' ; 3' ATGGTA 5'
5' GATATC 3' ; 3' CTACTA 5'
5' GAATTC 3' ; 3' CTTAAG 5'
16.
Who among the following was awarded the Nobel Prize for the development of PCR technique?
Herbert Boyer
Hargovind Khurana
Kary Mullis
Arthur Kornberg
17.
Which of the following bacteria is not a source of restriction endonuclease?
Haemophilus influenzae
Escherichia coli
Agrobacterium tumefaciens
Bacillus amyloli
18.
Molecular scissors which cut DNA at specific site is
Pectinase
Polymerase
Restriction endonuclease
Ligase
19.
Gel electrophoresis is used for
Construction of recombinant DNA by joining with cloning vectors
Isolation of DNA molecules
Cutting of DNA into fragments
Separation of DNA fragments according to their size
20.
The polymerase chain reaction is a technique that
Is used for in vivo replication of DNA
Is used for in vivo synthesis of mRNA
Is used for in vitro synthesis of mRNA
Is used for in vitro replication of specific DNA sequence using thermostable DNA polymerase
21.
The technique of genetic engineering includes
creation of recombinant DNA
use of gene cloning
gene transfer
All of these.
22.
One of the key factors, which makes the plasmid the vector in genetic engineering is that
It is resistant to antibiotics.
It is resistant to restriction enzymes.
Its ability to carry a foreign gene.
Its ability to cause infection in the host.
23.
Genetic engineering is possible because
the phenomenon of transduction in bacteria is well understood
we can see DNA by electron microscope
we can cut DNA at specific sites by endonucleases like DNAase 1
restriction endonucleases purified from bacteria can be used in vitro
24.
Two microbes found to be very useful in genetic engineering are
Crown gall bacterium and Coenorhabdities elegans
Escherichia coli and Agrobacterium tumefaciens
Vibria cholerae and a tailed bacteriophage
Diplococcus sp. and Pseudomonas sp.
25.
Viral genome incorporated into host DNA is called
Prophase
Prophage
Bacteriophage
None of these
26.
Restriction endonucleases are most widely used in recombinant DNA technology. They are obtained from
Bacteriophages
Bacterial cells
Plasmids
All prokaryotic cells
27.
Transgenic plants are developed by
clone and genetically modified genes
introduction of foreign genes
genetic engineering
purified genes
28.
What is the percentage of photosynthetically active radiation (PAR), if incident solar radiation is considered 100%?
100%
50%
1-5%
2-10%
29.
Second most important trophic level in a lake is
Phytoplankton
Zooplankton
Benthas
Fishes
30.
Which one of the following has the largest population in a food chain?
Producers
Primary consumers
Secondary consumers
Decomposers
1.
(c)
2.
(b)
gel electrophoresis
3.
(a)
introducing rDNA into plant cells
4.
(a)
always upright
5.
(c)
energy transfer from lower trophic level to higher trophic level
6.
(b)
cave
7.
(d)
tropical rain forest
8.
(c)
pyramid of biomass in a lake
9.
(b)
Gross production
10.
(d)
all of these
11.
(b)
GAATTC
12.
(b)
transformations of plant cells
13.
(c)
gene - transcription - mRNA - translation - protein
14.
(b)
cut DNA at specific locations
15.
(d)
5' GAATTC 3' ; 3' CTTAAG 5'
16.
(c)
Kary Mullis
17.
(c)
Agrobacterium tumefaciens
18.
(c)
Restriction endonuclease
19.
(d)
Separation of DNA fragments according to their size
20.
(d)
Is used for in vitro replication of specific DNA sequence using thermostable DNA polymerase
21.
(d)
All of these.
22.
(c)
Its ability to carry a foreign gene.
23.
(d)
restriction endonucleases purified from bacteria can be used in vitro
24.
(b)
Escherichia coli and Agrobacterium tumefaciens
25.
(b)
Prophage
26.
(b)
Bacterial cells
27.
(b)
introduction of foreign genes
28.
(b)
50%
29.
(b)
Zooplankton
30.
(a)
Producers
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