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Published on: 02/11/2025
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.
Reproductive isolation between segments of a single population is termed
sympatry
allopatry
population divergence
disruptive divergence
2.
Amphibians were dominant during
Carboniferous
silurian
ordovician
cambrian
jurassic
3.
Positive feedback loop signals from fully developed fetus and placenta ultimately lead to parturition which requires the release of
estrogen from the placenta
relaxing from placenta
oxytocin from fetal pituitary
oxytocin from maternal pituitary
4.
The embryo at 16 celled stage is known as
morula
gastrula
blastula
blastomere
5.
Hardy-Weinberg equilibrium is known to be affected by
evolution
limiting factors
saltation
natural selection
6.
One of the following is not a green house gas:
CO2
CH4
Ethane
N2O
7.
Which one of the following is incorrect about the characteristics of protobionts (coacervates and microspheres) as envisaged in the abiogenic origin of life?
they were partially isolated from the surroundings
they could maintain an internal environment
they were able to reproduce
they could separate combinations of molecules from the surroundings
8.
Transposons are:
house keeping genes
jumping genes
transporting genes
stationary genes
9.
Amniocentesis is a technique used to
Determine errors in amino acid metabolism in embryo
Pinpoint specific cardiac ailments in embryo
Determine any hereditary/genetic abnormality in embryo
All of these
10.
If global warming continues, the organism which may face more severe threat is
cow
banana
snow leopard
dolphin
11.
While analysing the DNA of an organism a total number of 5386 nucleotides were found out of which the proportion of different bases were: Adenine=29%, Guanine=17%, Cytosine=32%, Thymine=17%. Considering the Chargaffs rule it can be concluded that:
it is a double stranded circular DNA
it is single stranded DNA
it is a double stranded linear DNA
No conclusion can be drawn
12.
The correct sequence of spermatogenic stages leading to the formation of sperms in a mature human testis is
spermatogonia-spermatid-spermatocyte-sperms
spermatocyte-spermatogonia-spermatid-sperms
spermatogonia-spermatocyte-spermatid-sperms
spermatid-spermatocyte-spermatogonia-sperms
13.
In an aquatic ecosystem, the trophic level equivalent to cows in grasslands is
phytoplankton
zooplankton
nekton
benthos
14.
Mass of living matter at a trophic level in an area at any time is called
standing crop
detritus
humans
standing state
15.
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
16.
In a polluted environment, the maximum pollutant will occur to
primary produces
tertiary consumers
secondary consumers
primary consumers
17.
Which one of the following pairs of organisms are exotic species introduced in India?
Lantana camera, Water hyacinth
Water hyacinth, Prosopis cinereria
Nile perch, Ficus religiosa
Ficus religiosa, Lantana Camara
18.
Cuscuta is an example of
ectoparasitism
brood parasitism
predation
endoparasitism
19.
More than 70% of world's fresh water is contained in
polar ice
glaciers and mountains
Antarctica
Greenland
20.
Amensalism is an association between two species where:
one species is harmed and other is benefitted
one species is harmed and other is unaffected
one species is benefitted and other is unaffected
both the species are harmed
21.
A person with sickle cell anemia is
More prone to malaria
More prone to typhoid
Less prone to malaria
Less prone to typhoid
22.
Which one of the following processes results in the formation of clone of bacteria?
Transformation
Transduction
Binary Fission
Conjugation
23.
Which one of the following is a pair of endangered species?
Garden lizard and Mexican poppy
Rhesus monkey and sal tree
Indian peacock and Carrot grass
Hornbill and Indian Aconite
24.
In your opinion, which is the most effective way to consrve the plant diversity of an area?
by creating a biosphere reverse
by creating botanical gardens
By developing seed bank
By tissue culture method
25.
There are various types of reproduction. The type of reproduction adopted by an organism depends on:
The habitat and morphology of the organism
Morphology of the organism
Morphology and physiology of the organism
The organism's habitat, physiology and genetic makeup
26.
Sexual reproduction in fungi may occur by means of
Zporangiospore
Zoospore, oospore and ascospore
Sporangiospore, ascospore and basidiospore
Oospore, ascospore and basidiospore
27.
To speed up the malting process in brewing industry, the growth hormone used is
auxin
gibberellic acid
kinetin
ethylene
28.
A pea plant parent having violet colour flowers with unknown genotype was crossed with a plant having white colour flowers, in the progeny 50% flowers were violet and 50% were white. The genotypic constitution of the parent having violet colour flower was
Homozygous
Merozygous
Heterozygous
Hemizygous
29.
The popultation of an insect species show an explosive increase in numbers during rainly season followed by its disappearance at teh end of the season. What does this show?
the food plants mature and die at the end of the rainy season
its population growth curve is of J-type
the population of its predators increase
S-shaped or sigmoid growth of this insect.
30.
Which one of the following species of bees is used for the commercial production of honey?
Apis dorsata
Apis indica
Apis florea
Apis mellifera
31.
Match the following and choose the correct answer.
| column I | column II |
| A. Phobia | 1. Maladaptive hait |
| B. Neurosis | 2. Undue concern about health |
| C. Hypochondria | 3. Lack of sleep |
| D. Insomnia | 4. Intense feat |
A-2, B-1, C-4, D-3
A-2, B-1, C-3, D-4
A-4, B-1, C-3, D-2
A-3, B-4, C-2, D-1
A-4, B-1, C-2, D-3
32.
Select the statement which explains best parasitism.
One organism is benefitted.
Both the organisms are benefitted
One organism is benefitted, other is not affected
One organism is benefitted, other is affected.
33.
Embryo sac is to ovule __________ is to an anther
Stamen
Filament
Pollen grain
Androecium
34.
What is true about Bt toxin?
Bt toxin exists as active toxin in the Bacillus
The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication
The concerned Bacillus has anti toxins
The inactive prototoxin gets converted into active form in the insect gut
35.
Which of the following is commonly used in transfer of foreign DNA into crop plants?
Meloidogyne incognita
Agrobacterium tumefaciens
Penicillium expansum
Trichoderma harzianum
36.
Polyethylene glycol method is used for
Biodiesel production
Seedless fruit production
Energy production from sewage
Gene transfer without a vector
37.
The biggest constraint of plant breeding is :
availability of desirable gene in the crop and its wild relatives
infrastructure
trained manpower
transfer of genes from unrelated sources
38.
Golden rice is a promising transgenic crop. When released for cultivation, it will help in
Producing a petrol-like fuel from rice
alleviation of vitamin A
pest resistance
heribcide tolerance
39.
The two polynucleotide chains in DNA are
Discontinuous
Antiparallel
Semiconservative
Parallel
40.
The plant in which hugo de vries introduced the concept of multation
Oenothera lamarkiana
Pisum sativum
Allium cepa
Mirabilis jalapa
41.
Which one of the following is surrounded by a callose wall?
Male gamete
Egg
Pollen grain
Microspore mother cell
42.
Molecular scissors which cut DNA at specific site is
Pectinase
Polymerase
Restriction endonuclease
Ligase
43.
Indicate, the inheritance of which of the following is controlled by multiple alleles
Colour blindness
Sickle cell anaemia
Blood group
Phenylketoneuria
44.
Which one is the most important role of microorganism of the well being of humans?
sewage treatment
production of methane
production of SO2
conversion of milk to curd
45.
The linking of antibiotic resistance gene with the plasmid vector became possible with
DNA polymerase
Exonuclease
DNA ligase
Enonucleases
46.
Somaclonal variation appears in plants:
Growing in polluted soil or water
Exposed to gamma rays
Raised in tissue culture
Transformed by recombinant DNA technology
47.
In-vitro fertilization is a technique that involves transfer of which one of the following into the fallopian tube??
Zygote only
Embryo only, upto 8 cell stage
Either zygote or early embryo foetus
embryo of 32 cell stage
48.
If you suspect major deficiency of antibodies in a person, to which of the following would you look for confirmatory evidence?
Serum globulins
Fibrinogen in the plasma
Haemocytes
Serum albumins
49.
The correct surgical procedure as a contraceptive method is:
Ovariectomy
Hysterectomy
Vasectomy
Castration
50.
Morphine obtained from Opium is
Latex
Pome
Alkaloid
Tannin
51.
Anthesis is a phenomenon which refers to
Formation of pollen
Development of anther
the opening of a flower bud
Reception of pollen by stigma
52.
Initiator (starting) codon in eukaryotes is
AUG
AAG
CCU
GGC
53.
Given below are the four methods and their modes of action in achieving contraception.Select their correct matching from the four options that follows.
|
control measures |
Mode of Action |
| (A) Pill | 1. Prevents sperms reaching cervix |
| (B) Condom | 2. Prevents implication |
| (C)Vasectomy | 3. Prevents ovulation |
| (D) Copper T | 4. Semen contains no sperms |
| A | B | C | D |
| 3 | 4 | 1 | 2 |
| A | B | C | D |
| 2 | 3 | 1 | 4 |
| A | B | C | D |
| 3 | 1 | 4 | 2 |
| A | B | C | D |
| 4 | 1 | 2 | 3 |
54.
When a cluster of genes show linkage behaviour they
Do not show independent assortment
Do not show a chromosome map
Show recombination during meiosis
Induce cell division
55.
Cyclosporin-A an immunosuppressive drug is produced by
Aspergillus niger
Manascus purpureus
Penicillium notatum
Trichoderma polysporum
56.
The plant part which consists of two generations one within the other is
Germinated pollen grain
seed
Unfertilized ovule
Embryo
57.
Viral genome incorporated into host DNA is called
Prophase
Prophage
Bacteriophage
None of these
58.
In order to obtain disease-free plants through tissue culture techniques, the best method is
Embryo rescue
Anther culture
Protoplast culture
Meristem culture
59.
Bio fertilisers include:
Blue-green algae, rhizobia, other nitrogen fixing bacteria and mycorrhiza fungi
Blue-green algae, rhizobia and other nitrogen fixings bacteria
Rhizobia, other nitrogen fixing bacteria and mycorrhiza fungi
Blue green algae, rhizobia and mycorrhiza fungi
1.
(a)
sympatry
2.
(a)
Carboniferous
3.
(d)
oxytocin from maternal pituitary
4.
(c)
blastula
5.
(d)
natural selection
6.
(c)
Ethane
7.
(c)
they were able to reproduce
8.
(b)
jumping genes
9.
(c)
Determine any hereditary/genetic abnormality in embryo
10.
(c)
snow leopard
11.
(b)
it is single stranded DNA
12.
(c)
spermatogonia-spermatocyte-spermatid-sperms
13.
(b)
zooplankton
14.
(a)
standing crop
15.
(c)
energy transfer from lower trophic level to higher trophic level
16.
(b)
tertiary consumers
17.
(a)
Lantana camera, Water hyacinth
18.
(a)
ectoparasitism
19.
(a)
polar ice
20.
(c)
one species is benefitted and other is unaffected
21.
(c)
Less prone to malaria
22.
(c)
Binary Fission
23.
(d)
Hornbill and Indian Aconite
24.
(a)
by creating a biosphere reverse
25.
(d)
The organism's habitat, physiology and genetic makeup
26.
(d)
Oospore, ascospore and basidiospore
27.
(b)
gibberellic acid
28.
(c)
Heterozygous
29.
(b)
its population growth curve is of J-type
30.
(d)
Apis mellifera
31.
(e)
A-4, B-1, C-2, D-3
32.
(d)
One organism is benefitted, other is affected.
33.
(c)
Pollen grain
34.
(d)
The inactive prototoxin gets converted into active form in the insect gut
35.
(b)
Agrobacterium tumefaciens
36.
(d)
Gene transfer without a vector
37.
(d)
transfer of genes from unrelated sources
38.
(b)
alleviation of vitamin A
39.
(b)
Antiparallel
40.
(a)
Oenothera lamarkiana
41.
(d)
Microspore mother cell
42.
(c)
Restriction endonuclease
43.
(c)
Blood group
44.
(a)
sewage treatment
45.
(c)
DNA ligase
46.
(c)
Raised in tissue culture
47.
(c)
Either zygote or early embryo foetus
48.
(a)
Serum globulins
49.
(c)
Vasectomy
50.
(c)
Alkaloid
51.
(c)
the opening of a flower bud
52.
(a)
AUG
53.
(c)
| A | B | C | D |
| 3 | 1 | 4 | 2 |
54.
(a)
Do not show independent assortment
55.
(d)
Trichoderma polysporum
56.
(b)
seed
57.
(b)
Prophage
58.
(d)
Meristem culture
59.
(a)
Blue-green algae, rhizobia, other nitrogen fixing bacteria and mycorrhiza fungi
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