CBSE Class 12 Biology Important Questions All In One PDF – Free PDF Download

CBSE Important Questions for Class 12 Biology are prepared by the subject experts and are extensively helpful for students in their exam preparations. These important questions provide a strategy to prepare for various board examinations and other competitive exams.

Biology is the most important subject for students preparing for medical entrance exams, including  AIIMS, NEET, etc. Students aspiring to excel in the board and entrance examinations require deep knowledge and a thorough understanding of this subject. Therefore, the important questions for CBSE Class 12 Biology are essential for students to prepare for their exams.

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Biology MCQ Test Questions

Sexual Reproduction in Flowering Plants Class 12 Biology MCQs Pdf

Question 1.
What is the function of filiform apparatus in an angiospermic embryo sac?
(a) Brings about opening of the pollen tube
(b) Guides the pollen tube into a synergid
(c) Prevents entry of more than one pollen tube into a synergid
(d) None of these
Answer:
(b) Guides the pollen tube into a synergid

Question 2.
The female gametophyte of a typical dicot at the time of fertilisation is
(a) 8 – celled
(b) 7 – celled
(c) 6 – celled
(d) 5 – celled
Answer:
(b) 7 – celled

Question 3.
Polygonum type of embryo sac is
(a) 8 – nucleate, 7 – celled
(b) 8 – nucleate, 8 – celled
(c) 7 – nucleate, 7 – celled
(d) 4 – nucleate, 3 – celled
Answer:
(a) 8 – nucleate, 7 – celled

Question 4.
Both chasmogamous and cleistogamous flowers are present in
(a) Helianthus
(b) Commelina
(c) Rosa
(d) Gossypium
Answer:
(b) Commelina

Question 5.
Even in absence of pollinating agents seed-setting is assured in
(a) Commelina
(b) Zostera
(c) Salvia
(d) Fig
Answer:
(a) Commelina

Question 6.
Male and female flowers are present on different plants (dioecious) to ensure xenogamy, in
(a) papaya
(b) bottle gourd
(c) maize
(d) all of these.
Answer:
(a) papaya

Question 7.
Feathery stigma occurs in
(a) pea
(b) wheat
(c) Datura
(d) Caesalpinia
Answer:
(b) wheat

Question 8.
Plants with ovaries having only one or a few ovules are generally pollinated by
(a) bees
(b) butterflies
(c) birds
(d) wind
Answer:
(d) wind

Question 9.
Which of the following is not a water pollinated plant ?
(a) Zostera
(b) Vallisneria
(c) Hydrilla
(d) Cannabis
Answer:
(d) Cannabis

Question 10.
Spiny or sticky pollen grains and large, attractively coloured flowers are associated with
(a) hydrophily
(b) entomophily
(c) ornithophily
(d) anemophily
Answer:
(b) entomophily

Human Reproduction Class 12 Biology MCQs Pdf

Question 1.
Ovulation in the human female normally takes place during the menstrual cycle
(a) at the mind secretory phase
(b) just before the end of the secretory phase
(c) at the beginning of the proliferative phase
(d) at the end of the proliferative phase.
Answer:
(d) at the end of the proliferative phase.

Question 2.
After ovulation Graafian follicle regresses into
(a) corpus atresia
(b) corpus callosum
(c) corpus luteum
(d) corpus albicans
Answer:
(c) corpus luteum

Question 3.
Immediately after ovulation, the mammalian egg is covered by a membrane known as
(a) chorion
(b) zona pellucida
(c) corona radiata
(d) vitelline membrane.
Answer:
(c) corona radiata

Question 4.
Which one of the following events is correctly matched with the time period in a normal menstrual cycle ?
(a) Release of egg : 5 th day
(b) Endometrium regenerates : 5 – 10 days
(c) Endometrium secretes nutrients for implantation: 11 – 18 days
(d) Rise in progesterone level : 1 – 15 days
Answer:
(b) Endometrium regenerates : 5 – 10 days

Question 5.
If mammalian ovum fails to get fertilised, which one of the following is unlikely ?
(a) Corpus luteum will distintegrate.
(b) Progesterone secretion rapidly declines.
(c) Estrogen secretion increases.
(d) Primary follicle starts developing.
Answer:
(c) Estrogen secretion increases.

Question 6.
A human female reaches menopause aroung the age of
(a) 50 years
(b) 15 years
(c) 70 years
(d) 25 years.
Answer:
(a) 50 years

Question 7.
A reaction of granules content which harden the zona pellucida and ensures sure block to polyspermy is
(a) acrosomal reaction
(b) cortical reaction
(c) acrosin reaction
(d) bindin reaction.
Answer:
(b) cortical reaction

Question 8.
Which part of the sperm plays an important role in penetrating the egg membrane ?
(a) Allosome
(b) Tail
(c) Autosome
(d) Acrosome
Answer:
(d) Acrosome

Question 9.
In oocyte secondary maturation occurs in
(a) ovary
(b) abdominal cavity
(c) Fallopian tube
(d) uterus.
Answer:
(c) Fallopian tube

Question 10.
Besides activating the egg another role of a sperm is to carry to egg
(a) RNA
(b) mitochondria
(c) DNA
(d) ribosomes.
Answer:
(c) DNA

Reproductive Health Class 12 Biology MCQs Pdf

Question 1.
Which of the following is ART?
(a) IUDs
(b) GIFT
(c) ZIFT
(d) Both (b) & (c)
Answer:
(d) Both (b) & (c)

Question 2.
The technique called Gamete Intra Fallopian Transfer (GIFT) is recommended for those females
(a) who cannot produce an ovum
(b) who cannot retain the foetus inside uterus
(c) who cannot provide suitable environment for fertilisation
(d) all of these
Answer:
(a) who cannot produce an ovum

Question 3.
Which method can be used for women that cannot produce ovum but can provide suitable environment ?
(a) IUD
(b) GIFT
(c) IUI
(d) ICSI
Answer:
(b) GIFT

Question 4.
Which of these can be used to cure infertility in couples where male partner has very low sperm count ?
(a) IUD
(b) GIFT
(c) IUI
(d) None of these
Answer:
(c) IUI

Question 5.
The method of directly injecting a sperm into ovum in assisted reproductive technology is called
(a) GIFT
(b) ZIFT
(c) ICSI
(d) ET
Answer:
(c) ICSI

Question 6.
Increased IMR and decreased MMR in a population will
(a) cause rapid increase in growth rate
(b) result in decline in growth rate
(c) not cause significant change in growth rate
(d) result in an explosive population.
Answer:
(b) result in decline in growth rate

Question 7.
Intensely lactating mothers do not generally conceive due to the
(a) suppression of gonadotropins
(b) hypersecretion of gonadotropins .
(c) suppression of gametic transport
(d) suppression of fertilisation.
Answer:
(a) suppression of gonadotropins

Question 8.
A national level approach to build up a reproductively healthy society was taken up in our country in
(a) 1950s
(b) 1960s
(c) 1980s
(d) 1990s
Answer:
(a) 1950s

Question 9.
Emergency contraceptives are effective if used within,
(a) 72 hrs of coitus
(b) 72 hrs of ovulation
(c) 72 hrs of menstruation
(d) 72 hrs of implantation.
Answer:
(a) 72 hrs of coitus

Question 10.
From the sexually transmitted diseases mentioned below, identify the one which does not specifically affect the sex organs.
(a) Syphilis
(b) AIDS
(c) Gonorrhea
(d) Genital warts
Answer:
(b) AIDS

Principles of Inheritance and Variation Class 12 Biology MCQs Pdf

Question 1.
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is
(a) autosomal dominant
(b) autosomal recessive
(c) sex-linked dominant
(d) sex-linked recessive.
Answer:
(d) sex-linked recessive.

Question 2.
In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine ?
(a) GGG
(b) A AG
(c) G A A
(d) GUG
Answer:
(d) GUG

Question 3.
Person having genotype IA IB would show the blood group as AB. This is because of
(a) pleiotropy
(b) co-dominance
(c) segregation
(d) incomplete dominance.
Answer:
(b) co-dominance

Question 4.
ZZ/ZW type of sex determination is seen in
(a) platypus
(b) snails
(c) cockroach
(d) peacock
Answer:
(d) peacock

Question 5.
A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents ?
(a) TT and Tt
(b) Tt and Tt
(c) TT and TT
(d) Tt and It
Answer:
(b) TtandTt

Question 6.
In a dihybrid cross, if you get 9 : 3 : 3 : 1 ratio it denotes that
(a) the alleles of two genes are interacting with each other
(b) it is a multigenic inheritance
(c) it is a case of multiple allelism
(d) the alleles of two genes are segregating independently.
Answer:
(d) the alleles of two genes are segregating independently.

Question 7.
Which of the following will not result in variations among siblings ?
(a) Independent assortment of genes
(b) Crossing over
(c) Linkage
(d) Mutation
Answer:
(c) Linkage

Question 8.
Mendel’s Law of independent assortment holds good for genes situated on the
(a) non-homologous chromosomes
(b) homologous chromosomes
(c) extra nuclear genetic element
(d) same chromosome.
Answer:
(b) homologous chromosomes

Question 9.
Occasionally, a single gene may express more than one effect. The phenomenon is called
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny.
Answer:
(c) pleiotropy

Question 10.
In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are
(a) phenotypes – 4; genotypes – 16
(b) phenotypes – 9; genotypes – 4
(c) phenotypes – 4; genotypes – 8
(d) phenotypes – 4; genotypes – 9.
Answer:
(d) phenotypes – 4; genotypes – 9.

Molecular Basis of Inheritance Class 12 Biology MCQs Pdf

Question 1.
In a DNA strand the nucleotides are linked together by
(a) glycosidic bonds
(b) phosphodiester bonds
(c) peptide bonds
(d) hydorgen bonds.
Answer:
(b) phosphodiester bonds

Question 2.
The net electric charge on DNA and histones is
(a) both positive
(b) both negative
(c) negative and positive, respectively
(d) zero.
Answer:
(c) negative and positive, respectively

Question 3.
Which of the following statements is the most appropriate for sickle cell anaemia ?
(a) It cannot be treated with iron supplements.
(b) It is a molecular disease.
(c) It conferes resistance to acquiring malaria.
(d) All of the above.
Answer:
(d) All of the above.

Question 4.
The first genetic material could be
(a) protein
(b) cabohydrates
(c) DNA
(d) RNA.
Answer:
(d) RNA.

Question 5.
The human chromosome with the highest and least number of genes in them are respectively
(a) chromosome 21 and Y
(b) chromosome 1 and X
(c) chromosome 1 and Y
(d) chromosome X and Y.
Answer:
(c) chromosome 1 and Y

Question 6.
Who amongst the following scientist had no contribution in the development of the double helix model for the structure of DN A ?
(a) Rosalind Franklin
(b) Maurice Wilkins
(c) Erwin Chargaff
(d) Meselson and Stahl
Answer:
(b) Maurice Wilkins

Question 7.
Which of the following steps in transcription is catalysed by RNA polymerase ?
(a) Initiation
(b) Elongation
(c) Termination
(d) All of the above
Answer:
(d) All of the above

Question 8.
Control of gene expression takes place at the level of
(a) DNA-replication
(b) transcription
(c) translation
(d) none of the above.
Answer:
(b) transcription

Question 9.
Which was the last human chromosome to be completely sequenced ?
(a) Chromosome 1
(b) Chromosome 11
(c) Chromosome 21
(d) Chromosome X
Answer:
(a) Chromosome 1

Question 10.
In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called
(a) A – DNA
(b) B – DNA
(c) cDNA
(d) rDNA.
Answer:
(c) cDNA

Evolution Class 12 Biology MCQs Pdf

Question 1.
The theory of spontaneous generation stated that
(a) life arose from living forms only
(b) life can arise from both living and non-living
(c) life can arise from non-living things only
(d) life arises spontaneusly, neither from living nor from the non-living.
Answer:
(c) life can arise from non-living things only

Question 2.
Animal husbandry and plant breeding programmes are the examples of
(a) reverse evolution
(b) aritifical selection
(c) mutation
(d) natural selection.
Answer:
(d) natural selection.

Question 3.
Palaentological evidences for evolutaion refer to the
(a) development of embryo
(b) homologous organs
(c) fossils
(d) analogous organs.
Answer:
(c) fossils

Question 4.
The bones of forelimbs of whale, bat, cheeah and man are similar in structure, because
(a) one organism has given rise to another
(b) they share a common ancestor
(c) they perform the same function.
(d) the have biochemical similarities.
Answer:
(b) they share a common ancestor

Question 5.
Analogous organs arise due to
(a) divergent evolution
(b) artificial selection
(c) genetic drift
(d) convergent evolution.
Answer:
(d) convergent evolution.

Question 6.
(p+q)2 = p2 + 2pq + q2 = 1 represents an equation used in
(a) population genetics
(b) Mendilian genetics
(c) biometircs
(d) molecular genetics.
Answer:
(a) population genetics

Question 7.
Appearnace of antibiotic-resistant bacteria is an example of
(a) adaptive radiation
(b) transduction
(c) pre-existing variation in the population
(d) divergent evolution.
Answer:
(c) pre-existing variation in the population

Question 8.
Fossils are generally found in
(a) sedimentasry rocks
(b) igneous rocks
(c) metamorphic rocks
(d) any type of rock.
Answer:
(a) sedimentasry rocks

Question 9.
Which type of selection is industrial melanism observed in moth, Biston betularia?
(a) Stabilising
(b) Directional
(c) Disruptive
(d) Artificial
Answer:
(b) Directional

Question 10.
Which of the following is an example for link species ?
(a) Lobe fish
(b) Dodo bird
(c) Seaweed
(d) Chimpanzee
Answer:
(a) Lobe fish

Human Health and Disease Class 12 Biology MCQs Pdf

Question 1.
AIDS is caused by HIV. Among the following, which one is not a mode of transmission of HIV?
(a) Transfusion of contaminated blood.
(b) Sharing the infected needles.
(c) Shaking hands with infected persons.
(d) Sexual contact with infected persons.
Answer:
(c) Shaking hands with infected persons.

Question 2.
‘Smack’ is a drug obtained from the
(a) latex of Papever somniferum
(b) leaves of Cannabis saliva
(c) flowers of Datura
(d) fruits of Erythroxyl coca.
Answer:
(a) latex of Papever somniferum

Question 3.
The substance produced by a cell in viral infection that can protect other cells from further infection is
(a) serotonin
(b) colostrum
(c) interferon
(d) histamine.
Answer:
(c) interferon

Question 4.
Antibodies present in colostrum which protect the new born from certain diseases is of
(a) IgG type
(b) IgA type
(c) IgD type
(d) IgE type.
Answer:
(b) IgA type

Question 5.
Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be
(a) nicotine
(b) tannic acid
(c) curaimin
(d) catechin.
Answer:
(a) nicotine

Question 6.
Antivenom against snake poison contains
(a) antigens
(b) antigen-antibody complexes
(c) antibodies
(d) enzymes
Answer:
(c) antibodies

Question 7.
Which of the following is not a lymphoid tissue ?
(a) Spleen
(b) Tonsils
(c) Pancreas
(d) Thymus
Answer:
(c) Pancreas

Question 8.
Which of the following glands is large sized at birth but reduces in size with ageing ?
(a) Pineal
(b) Pituitary
(c) Thymus
(d) Thyroid
Answer:
(c) Thymus

Question 9.
Haemozoin is a
(a) precursor of haemoglobin
(b) toxin released from Streptococcus infected cells
(c) toxin released from Plasmodium infected cells
(d) toxin released from Haemophilus infected cells.
Answer:
(c) toxin released from Plasmodium infected cells

Question 10.
One of the following is not the causal organism for ringworm.
(a) Microsporum
(b) Trichophyton
(c) Epidermophyton
(d) Macrosporum
Answer:
(d) Macrosporum

Biotechnology: Principles and Processes Class 12 MCQs Questions with Answers

Question 1.
Micro-organisms can be grown in the bioreactors by
(a) Support growth system
(b) Agitated growth system
(c) Suspended .growth system
(d) Both (a) and (c)

Answer

Answer: (d) Both (a) and (c)


Question 2.
Name the drug used in cancer treatment produced by using biotechnology
(a) Terramycin
(b) HGH
(c) Insulin
(d) TSH
(e) Enterferon

Answer

Answer: (b) HGH


Question 3.
During ‘gene cloning’ which is called as ‘gene taxi’?
(a) Vaccine
(b) Plasmid
(c) Bacterium
(d) Protozoa

Answer

Answer: (b) Plasmid


Question 4.
Hybridoma technology has been successfully used in
(a) production of somatic hybrids
(b) synthesis of monoclonal antibodies
(c) synthesis of haemoglobin
(d) production of alcohol in bulk

Answer

Answer: (b) synthesis of monoclonal antibodies


Question 5.
Introduction of food plants developed by genetic engineering is not desirable because
(a) These products are less tasty as compared to the already existing products
(b) The method is costly
(c) Economy of developing countries may suffer.
(d) There is danger of entry of viruses and toxins with introduced crop

Answer

Answer: (a) These products are less tasty as compared to the already existing products


Question 6.
Hybridoma cells are
(a) Nervous cells of frog
(b) Hybrid cells resulting from myeloma cells
(c) Only cells having oncogenes
(d) Product of spore formation in bacteria

Answer

Answer: (b) Hybrid cells resulting from myeloma cells


Question 7.
The new strain of bacteria produced by biotechnology in alcohol industry is
(a) Escherichia coli
(b) Saccharomyces cerevisiae
(c) Bacillus sabtilis
(d) Pseudomonas putida

Answer

Answer: (d) Pseudomonas putida


Question 8.
Important objective of biotechnology in agriculture section is
(a) To produce pest resistant varieties of plants
(b) To increase the nitrogen content
(c) To decrease the seed number
(d) To increase the plant weight

Answer

Answer: (a) To produce pest resistant varieties of plants


Question 9.
The two vitamins manufactured biotechnologically are
(a) Vitamin B12 and Vitamin B6
(b) Vitamin B12 and Vitamin B2
(c) Vitamin B6 and Vitamin B2
(d) Vitamin B12 and Vitamin B9

Answer

Answer: (b) Vitamin B12 and Vitamin B2


Question 10.
Some pathogenic bacteria develop resistance to antibiotics by
(a) Modifying their cell walls
(b) Developing such enzymes which modify antibiotics
(c) Alter the antibiotics target due to spontaneous mutation
(d) All the above.

Answer

Answer: (d) All the above.



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