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Class 12 Biology Question Answers

Question Answer

Class 12

Biology

Master Class 12 Biology: Engag...

Last updated date: 17th Sep 2024

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Class 12 Biology Question Answers

What is Biological Magnification ?

Give 10 examples of unisexual and bisexual flowers

Flowering in Pineapple is promoted byA. GAB. IAAC. EthyleneD. Both B and C

What are stomata? Write its functions?

Which one of the following has maximum genetic diversity in India?A. TeakB. MangoC. WheatD. Tea

Xenia and metaxenia terms are related toA. Pollen cultureB. Only endospermC. Xylem and phloem D. Pollen and endosperm

Parbhani Kranti a variety of bhindi (lady’s finger) is resistant toA. Bacterial blightB. Yellow mosaic virusC. Black rotD. Leaf curl

The sex chromosomes of both male and female are respectivelyA) YY XXB) YX XYC) XY XXD) All of the above

Most widely used bioweapon is A. Bacillus subtilis B. Pseudomonas putida C. Bacillus anthracis D. None of the above

Describe the importance of variation.

Body of Euspongia is mainly composed of(a) Calcareous spicules(b) Spongin fibers(c) Siliceous spicules(d) Mesoglea

Which is the most abundant plant pigment in the world?A. Chlorophyll aB. Chlorophyll bC. Chlorophyll cD. Chlorophyll d

Mendel observed 7 pairs of contrasting characters in Pisum sativum. One of the following is not a part of that. Find out.A. Tall and dwarf stemB. Yellow and green seed colorC. Terminal and axial flowerD. Smooth and rough stem

The major function of the contractile vacuole isa. Excretionb. Storagec. Osmoregulationd. Circulation

An aggregate fruit is one which developed froma. Multicarpellary syncarpous gynoeciumb. Multicarpellary apocarpous gynoeciumc. Complete inflorescenced. Multicarpellary superior ovary

Would there be bacteria present in the aquarium?

A characteristic of angiosperm isa) Flowersb) Rootsc) Seedd) All of these

How many hotspots of biodiversity in the world have been identified till date by Norman Myers? A) 34B) 43C) 17D) 25

Genetic drift operates in(a) Non-reproduction population(b) Slow reproduction population(c) Small isolated population(d) Large isolated population

Give two examples of microbial pesticides with their hosts.

Acrosome reaction in sperm is triggered byA. CapacitationB. Release of lysineC. Influx of Na+D. Release of fertilizin

All types of successions leads to. A. Xeric climax community B. Hydric climax community C. Mesic climax community D. Any climax community depending on the nature of the habitat

Rarely in angiosperms the pollen tube develops further in the embryo sac. The abnormality is called as-A. MetaxeniaB. Nemec phenomenonC. XeniaD. Mesogamy

Theory of pangenesis was given byA. KerensB. MendelC. De VriesD. Darwin

The raw materials for photosynthesis areA. CO$_2$ and O$_2$B. Sunlight O$_2$ and CO$_2$C. Water and chlorophyll.D. CO$_2$ and water.

A homozygous inflated pod shaped variety of pea plant (I) is crossed with a constricted variety of pea plant (i). Answer the question that follows:State the Mendel’s law of dominance.

Recurrent apomixis is a. Parthenogenesis b. Diploid parthenogenesis c. Haploid parthenogenesis d. None of the above

Which weed is known as the “terror of Bengal”? Why is it very difficult to get rid of them from the water bodies?

The kernel color of wheat is determined by _______ gene-a. Oneb. Twoc. Threed. Five

The first clinical gene therapy was done for the treatment of ______.(A) AIDS(B) Cancer(C) Cystic fibrosis(D) SCID (Severe Combined Immuno Deficiency resulting from deficiency of ADA)

Dolphins and whales have gills to breathe in water.a. Trueb. False

stone canal of starfish is-?A.Reproductive canalB. Respiratory canalC. Excretory canalD. None of the above

The mutation theory of evolution was proposed by:a. Darwinb. Hugo de Vriesc. Lamarckd. Huxley

The egg is returned to mother’s body during test tube baby formation when it reachesa. 8 cell stageb. 16 cell stagec. 8 or 16 cell staged. None of the above

Anti-venom injection contains preformed antibodies while polio drops that are administered into body contain(a) Activated pathogens(b) Harvested antibodies(c) Gamma globulin(d) Attenuated pathogens

Natural reservoir of phosphorus isA. Animal bonesB. RockC. FossilsD. Sea water

CAT stands forA) Computerised axial tomographyB) Computerised automated tomographyC) Computational axial tomographyD) None of the above

Red Blood Cells are known as A) ErythrocytesB) LeukocytesC) NeurocytesD) Oxycytes

Norin-10 is famous for the A. Gigas effect.B. Dwarfine effect.C. Aromatic effect.D. Early maturation effect.

What is the Full Form of DNA and RNA ?

What is the basic difference between binary fission and budding?A. In budding the parents’ identity is lost while in binary fission it is maintained.B. In binary fission the parent identity is lost while it is maintained in budding.C. There is a fusion of daughter cells in binary fission while in budding genetically non-identical daughter cells are produced.D. In binary fission two dissimilar individuals (daughter cells) are forced while in budding daughter and parent cells are similar.

Explain biomagnification of DDT in an aquatic food chain. How does it affect the bird population?

Tendrils in plants are an example of A. Convergent evolutionB. RadiationC. DivergentD. Coevolution

The microbe Pseudomonas denitrificans produces which vitamin?(a) K(b) D(c) B2(d) B12

In a type of apomixis known as adventive embryony embryos develop directly from the(a) Nucellus or integuments(b) Synergids or antipodals in an embryo sac(c) Accessory embryo sacs in an ovule (d) Zygote

Most abundant immunoglobulin is A. IgAB. IgEC. IgGD. IgM

Parthenocarp is a fruitA. Formed from a superior ovaryB. Formed from an inferior ovaryC. Consisting of ripened ovary and thalamusD. Which does not possess seeds

Describe the life cycle of Plasmodium vivax in a man?

Select the secondary consumer.a. A fish that feeds on algae.b. A hawk that feeds on a mouse that feeds on an insect.c. A plant that is parasitic to another plant.d. A lion that eats a gazelle that feeds on grass.e. A beetle that feeds on nectar.

Vegetative reproduction in cycas occurs by (a) Sporophyll(b) Bulbils(c) Scaly leaves(d) Fragmentation

Describe any two applications of tissue culture technique.

Basic event in reproduction is the creation of DNA copy.A. TrueB. False

Sketch and label seminiferous tubules in the TS of testis.

Describe Avery McLeod and McCarty's experiment. State its significance.

Which of the following is polygamous plant?A. MangoB. Pink flowerC. RoseD. Gossypium

Mention the respiratory quotient (RQ) value for carbohydrates fats and protein during aerobic respiration.

Scientific name of green gram isA) Vigna mungoB) Vigna radiataC) Phaseolus mungoD) Phaseolus sinensis

The bacterium which reduces the fertility of soil isA) NitrosomonasB) Bacillus denitrificansC) Azotobacter sp.D) Nitrobacter

The linkage map of X chromosome of fruit fly has $66$ units with yellow body gene (y) at one end and bobbed hair (b) gene at the other end. The recombination frequency between these two genes (y and b) should beA. $60%$ B. $50%$ C. $\\le 50%$D. $100%$

The absence of which of the following clotting factors leads to haemophilia A?A. Factor VIIB. Factor VIIIC. Factor IXD. Factor X

The total set of DNA present in a cell is called as: a. Genomeb. Codonc. Anticodond. Gene

Teeth in frog areA)HomodontB)AcrodontC)Heterodont D)Both A and B

Transcription in eukaryotic cell takes place in A) NucleusB) RibosomeC) Endoplasmic reticulumD) Golgi bodyE) Cytoplasm

The thermostable enzymes Taq and Pfu isolated from thermophilic bacteria are A. RNA polymerasesB. DNA LigasesC. DNA polymerasesD. Restriction endonucleases

Lactobacillus mediated conversion of milk to curd results because ofA) Coagulation and partial digestion of milk fats.B) Coagulation and partial digestion of milk proteinsC) Coagulation of milk proteins and complete digestion of milk fatsD) Coagulation of milk fats and complete digestion milk protein.

Explain how a hydrarch succession progresses from hydric to mesic condition and forms a stable climax community.

Compound apocarpous gynoecium is found inA. Lily AB. HollyhockC. Lotus or RanunculusD. Pumpkin

Infective stage of plasmodium isa. Trophozoiteb. Merozoitec. Schizontd. Sporozoite

Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present.

Why should we conserve biodiversity?A. We should preserve the biodiversity we have inheritedB. A loss of diversity may lead to a loss of ecological stabilityC. Both A and BD. None of these

8 shaped nervous system belongs toA. PilaB. UnioC. AnodontaD. All of the above

What are the homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

Why is earthworm considered a farmer’s friend? Explain humification and mineralisation occurring in a decomposition cycle.

Why is a starter culture added to set the milk to curd? Explain?

Spinal cord originates from cerebellum(a) True(b) False

When a cell reproduces what happens to its DNA? Is it copied and incorporated into offspring?

Ectophloic siphonostele is found in (a) Adiantum and Cucurbitaceae (b) Osmunda and Equisetum (c) Marsilea and Botrychium (d) Dicksonia and Adiantum

Brain sugar isA) LactoseB) GlucoseC) FructoseD) Galactose

Write a note on the coagulation of blood.

What do you think – Is vegetative reproduction also a type of asexual reproduction? Why do you say so? Is the term clone applicable to the offspring formed by vegetative reproduction?

Name the instrument used to measure heartbeat.

Choose the correct option:The heterosporous pteridophytes are _______________.a) Lycopodium and Pterisb) Selaginella and Psilotumc) Selaginella and Salviniad) Dryopteris and Adiantum

Which climatic zone of the Earth has more animals and why?

Which site of a tRNA molecule forms hydrogen bonds with mRNA?A) CodonB) AnticodonC) 5’ end of the tRNAD) 3’ end of the tRNA

Choose the correct option:In an ecosystem decomposers includea) Microscopic organisms b) Algae c) Bacteria Fungi d) All plants

Explain the difference between nucleoside and nucleotide.

Which of the following is a long day plant(a) Poppy(b) Xanthium(c) Paddy(d) Soybean

Free nuclear division occurs in.a) Flowerb) Gametesc) Endospermd) Fruit

Formation of the ozone hole is maximum over (a) India (b) Antarctica(c) Europe(d) Africa

The hormone injected to cows for excessive milk production is:A. OestrogenB. ProgesteroneC. OxytocinD. Testosterone

In which part of the cell is DNA concentrated?

Which of the following is a protozoan disease?(a)Malaria(b)Typhoid(c)AIDS(d)Cholera

What is poor health?

How many sperm and ova will be produced from 25 primary spermatocytes and 25 primary oocytes respectively?a. 100 sperm and 50 ovab. 50 sperm and 25 ovac. 100 sperm and 100 ovad. 100 sperm and 25 ova

Which of the following is incorrectly paired?a. SRY gene-X chromosomeb. 2n-2- Nullisomicc. Nucleoid Prokaryoticd. Polytene chromosome-Drosophilae. Trisomy - Down's syndrome

Smallest man like ape isA) ChimpanzeeB) OrangutanC) SlothD) Gibbon

English physician who first observed blood circulation wasA) J.C. BoseB) A. VesaliusC) Wiliam HarveyD) H.G.Khorana

Combination of apoenzyme and coenzyme producesa) Prosthetic groupb) Holoenzymes c) Enzyme substrate complexd) Enzyme- product complex

Draw the structure of the chromosome and label its parts.

The two accessory photosynthetic pigments present in the leaves are A. Carotene and chlorophyll B. Xanthophyll and chlorophyllC. Anthocyanin and carotene D. Xanthophyll and carotene

What is Biological Magnification ?

Give 10 examples of unisexual and bisexual flowers

Flowering in Pineapple is promoted byA. GAB. IAAC. EthyleneD. Both B and C

What are stomata? Write its functions?

Which one of the following has maximum genetic diversity in India?A. TeakB. MangoC. WheatD. Tea

Xenia and metaxenia terms are related toA. Pollen cultureB. Only endospermC. Xylem and phloem D. Pollen and endosperm

Parbhani Kranti a variety of bhindi (lady’s finger) is resistant toA. Bacterial blightB. Yellow mosaic virusC. Black rotD. Leaf curl

The sex chromosomes of both male and female are respectivelyA) YY XXB) YX XYC) XY XXD) All of the above

Most widely used bioweapon is A. Bacillus subtilis B. Pseudomonas putida C. Bacillus anthracis D. None of the above

Describe the importance of variation.

Body of Euspongia is mainly composed of(a) Calcareous spicules(b) Spongin fibers(c) Siliceous spicules(d) Mesoglea

Which is the most abundant plant pigment in the world?A. Chlorophyll aB. Chlorophyll bC. Chlorophyll cD. Chlorophyll d

The major function of the contractile vacuole isa. Excretionb. Storagec. Osmoregulationd. Circulation

An aggregate fruit is one which developed froma. Multicarpellary syncarpous gynoeciumb. Multicarpellary apocarpous gynoeciumc. Complete inflorescenced. Multicarpellary superior ovary

Would there be bacteria present in the aquarium?

A characteristic of angiosperm isa) Flowersb) Rootsc) Seedd) All of these

How many hotspots of biodiversity in the world have been identified till date by Norman Myers? A) 34B) 43C) 17D) 25

Genetic drift operates in(a) Non-reproduction population(b) Slow reproduction population(c) Small isolated population(d) Large isolated population

Give two examples of microbial pesticides with their hosts.

Acrosome reaction in sperm is triggered byA. CapacitationB. Release of lysineC. Influx of Na+D. Release of fertilizin

All types of successions leads to. A. Xeric climax community B. Hydric climax community C. Mesic climax community D. Any climax community depending on the nature of the habitat

Rarely in angiosperms the pollen tube develops further in the embryo sac. The abnormality is called as-A. MetaxeniaB. Nemec phenomenonC. XeniaD. Mesogamy

Theory of pangenesis was given byA. KerensB. MendelC. De VriesD. Darwin

The raw materials for photosynthesis areA. CO$_2$ and O$_2$B. Sunlight O$_2$ and CO$_2$C. Water and chlorophyll.D. CO$_2$ and water.

A homozygous inflated pod shaped variety of pea plant (I) is crossed with a constricted variety of pea plant (i). Answer the question that follows:State the Mendel’s law of dominance.

Recurrent apomixis is a. Parthenogenesis b. Diploid parthenogenesis c. Haploid parthenogenesis d. None of the above

Which weed is known as the “terror of Bengal”? Why is it very difficult to get rid of them from the water bodies?

The kernel color of wheat is determined by _______ gene-a. Oneb. Twoc. Threed. Five

The first clinical gene therapy was done for the treatment of ______.(A) AIDS(B) Cancer(C) Cystic fibrosis(D) SCID (Severe Combined Immuno Deficiency resulting from deficiency of ADA)

Dolphins and whales have gills to breathe in water.a. Trueb. False

stone canal of starfish is-?A.Reproductive canalB. Respiratory canalC. Excretory canalD. None of the above

The mutation theory of evolution was proposed by:a. Darwinb. Hugo de Vriesc. Lamarckd. Huxley

The egg is returned to mother’s body during test tube baby formation when it reachesa. 8 cell stageb. 16 cell stagec. 8 or 16 cell staged. None of the above

Anti-venom injection contains preformed antibodies while polio drops that are administered into body contain(a) Activated pathogens(b) Harvested antibodies(c) Gamma globulin(d) Attenuated pathogens

Natural reservoir of phosphorus isA. Animal bonesB. RockC. FossilsD. Sea water

CAT stands forA) Computerised axial tomographyB) Computerised automated tomographyC) Computational axial tomographyD) None of the above

Red Blood Cells are known as A) ErythrocytesB) LeukocytesC) NeurocytesD) Oxycytes

Norin-10 is famous for the A. Gigas effect.B. Dwarfine effect.C. Aromatic effect.D. Early maturation effect.

What is the Full Form of DNA and RNA ?

Explain biomagnification of DDT in an aquatic food chain. How does it affect the bird population?

Tendrils in plants are an example of A. Convergent evolutionB. RadiationC. DivergentD. Coevolution

The microbe Pseudomonas denitrificans produces which vitamin?(a) K(b) D(c) B2(d) B12

Most abundant immunoglobulin is A. IgAB. IgEC. IgGD. IgM

Parthenocarp is a fruitA. Formed from a superior ovaryB. Formed from an inferior ovaryC. Consisting of ripened ovary and thalamusD. Which does not possess seeds

Describe the life cycle of Plasmodium vivax in a man?

Vegetative reproduction in cycas occurs by (a) Sporophyll(b) Bulbils(c) Scaly leaves(d) Fragmentation

Describe any two applications of tissue culture technique.

Basic event in reproduction is the creation of DNA copy.A. TrueB. False

Sketch and label seminiferous tubules in the TS of testis.

Describe Avery McLeod and McCarty's experiment. State its significance.

Which of the following is polygamous plant?A. MangoB. Pink flowerC. RoseD. Gossypium

Mention the respiratory quotient (RQ) value for carbohydrates fats and protein during aerobic respiration.

Scientific name of green gram isA) Vigna mungoB) Vigna radiataC) Phaseolus mungoD) Phaseolus sinensis

The bacterium which reduces the fertility of soil isA) NitrosomonasB) Bacillus denitrificansC) Azotobacter sp.D) Nitrobacter

The absence of which of the following clotting factors leads to haemophilia A?A. Factor VIIB. Factor VIIIC. Factor IXD. Factor X

The total set of DNA present in a cell is called as: a. Genomeb. Codonc. Anticodond. Gene

Teeth in frog areA)HomodontB)AcrodontC)Heterodont D)Both A and B

Transcription in eukaryotic cell takes place in A) NucleusB) RibosomeC) Endoplasmic reticulumD) Golgi bodyE) Cytoplasm

The thermostable enzymes Taq and Pfu isolated from thermophilic bacteria are A. RNA polymerasesB. DNA LigasesC. DNA polymerasesD. Restriction endonucleases

Explain how a hydrarch succession progresses from hydric to mesic condition and forms a stable climax community.

Compound apocarpous gynoecium is found inA. Lily AB. HollyhockC. Lotus or RanunculusD. Pumpkin

Infective stage of plasmodium isa. Trophozoiteb. Merozoitec. Schizontd. Sporozoite

Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present.

Why should we conserve biodiversity?A. We should preserve the biodiversity we have inheritedB. A loss of diversity may lead to a loss of ecological stabilityC. Both A and BD. None of these

8 shaped nervous system belongs toA. PilaB. UnioC. AnodontaD. All of the above

What are the homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

Why is earthworm considered a farmer’s friend? Explain humification and mineralisation occurring in a decomposition cycle.

Why is a starter culture added to set the milk to curd? Explain?

Spinal cord originates from cerebellum(a) True(b) False

When a cell reproduces what happens to its DNA? Is it copied and incorporated into offspring?

Ectophloic siphonostele is found in (a) Adiantum and Cucurbitaceae (b) Osmunda and Equisetum (c) Marsilea and Botrychium (d) Dicksonia and Adiantum

Brain sugar isA) LactoseB) GlucoseC) FructoseD) Galactose

Write a note on the coagulation of blood.

What do you think – Is vegetative reproduction also a type of asexual reproduction? Why do you say so? Is the term clone applicable to the offspring formed by vegetative reproduction?

Name the instrument used to measure heartbeat.

Choose the correct option:The heterosporous pteridophytes are _______________.a) Lycopodium and Pterisb) Selaginella and Psilotumc) Selaginella and Salviniad) Dryopteris and Adiantum

Which climatic zone of the Earth has more animals and why?

Which site of a tRNA molecule forms hydrogen bonds with mRNA?A) CodonB) AnticodonC) 5’ end of the tRNAD) 3’ end of the tRNA

Choose the correct option:In an ecosystem decomposers includea) Microscopic organisms b) Algae c) Bacteria Fungi d) All plants

Explain the difference between nucleoside and nucleotide.

Which of the following is a long day plant(a) Poppy(b) Xanthium(c) Paddy(d) Soybean

Free nuclear division occurs in.a) Flowerb) Gametesc) Endospermd) Fruit

Formation of the ozone hole is maximum over (a) India (b) Antarctica(c) Europe(d) Africa

The hormone injected to cows for excessive milk production is:A. OestrogenB. ProgesteroneC. OxytocinD. Testosterone

In which part of the cell is DNA concentrated?

Which of the following is a protozoan disease?(a)Malaria(b)Typhoid(c)AIDS(d)Cholera

What is poor health?

How many sperm and ova will be produced from 25 primary spermatocytes and 25 primary oocytes respectively?a. 100 sperm and 50 ovab. 50 sperm and 25 ovac. 100 sperm and 100 ovad. 100 sperm and 25 ova

Which of the following is incorrectly paired?a. SRY gene-X chromosomeb. 2n-2- Nullisomicc. Nucleoid Prokaryoticd. Polytene chromosome-Drosophilae. Trisomy - Down's syndrome

Smallest man like ape isA) ChimpanzeeB) OrangutanC) SlothD) Gibbon

English physician who first observed blood circulation wasA) J.C. BoseB) A. VesaliusC) Wiliam HarveyD) H.G.Khorana

Combination of apoenzyme and coenzyme producesa) Prosthetic groupb) Holoenzymes c) Enzyme substrate complexd) Enzyme- product complex

Draw the structure of the chromosome and label its parts.

The two accessory photosynthetic pigments present in the leaves are A. Carotene and chlorophyll B. Xanthophyll and chlorophyllC. Anthocyanin and carotene D. Xanthophyll and carotene