HBSE Class 12th Biology Important Questions with Answer 2024

Haryana Board Class 12th Biology Important Questions with Answer 2024. HBSE Class 12 Biology Important Questions 2024. BSEH Class 12 Biology vv important Questions 2024. Class 12 Biology Most important questions for Board Exam 2024. हरियाण बोर्ड कक्षा 12 जीव विज्ञान के अति महत्वपूर्ण प्रश्न 2024.

HBSE Class 12th Biology Important Questions with Answer 2024


Objective Questions

1. Birth rate is called :
(a) Mortality
(b) Emigration
(c) Inmigration
(d) Natality
Answer – (d) Natality

2. The coconut water from tender coconut is :
(a) Cellular endosperm
(b) Free nuclear endosperm
(c) Both cellular and nuclear endosperm
(d) Free nuclear embryo
Answer – (b) Free nuclear endosperm

3. Apomictic embryos in citrus arise from :
(a) Diploid egg
(b) Synergids
(c) Nucellus
(d) Antipodal cells
Answer – (c) Nucellus

4. A pregnant women is having prolonged labour pains and childbirth has to fastened it is advisable to administer a hormone that can :
(a) increase the metabolic rate
(b) release glucose in blood
(c) stimulates the ovary
(d) activate smooth muscles
Answer – (d) activate smooth muscles

5. A procedure that finds use in testing for genetic disorders but is also misused for female foeticide is :
(a) Lactational amenorrhea
(b) Amniocentesis
(c) Artificial insemination
(d) Parturition
Answer – (b) Amniocentesis

6. In human beings where genotype AABBCC represents dark skin colour, aabbcc represents light skin colour and AaBbCc represents in intermediate skin colour the pattern of genetic inheritance can be termed as :
(a) Pleiotropy and codominance
(b) Pleiotropy and incomplete
(c) Polygenic and qualitative inheritance
(d) Polygenic and quantitative inheritance
Answer – (d) Polygenic and quantitative inheritance

7. Chromosomal theory of inheritance was proposed by :
(a) Watson and Crick
(b) Sutton and Boveri
(c) Bateson and Punnet
(d) T.H Morgan
Answer – (b) Sutton and Boveri

8. All of the following are part of an operon except :
(a) Structural genes
(b) An enhancer
(c) An operator
(d) A promoter
Answer – (b) An enhancer

9. The equivalent of structural gene is :
(a) Operon
(b) Recon
(c) Mutan
(d) Cistron
Answer – (d) Cistron

10. Evolution of life shows that life forms had a trend of moving from :
(a) land to water
(b) dryland to wetland
(c) freshwater to sea water
(d) Water to land
Answer – (d) Water to land

11. Palaentological evidences for evolution refer to the :
(a) Development of embryo
(b) Homologous organs
(c) Fossils
(d) Analogous organs
Answer – (c) Fossils

12. Which of the following would appear as the pioneer organisms on bare rock?
(a) Green algae
(b) Lichens
(c) Liverworts
(d) Mosses
Answer – (b) Lichens

13. Which one of the following is not a method of in situ conservation of biodiversity?
(a) Biosphere Reserve
(b) Wildlife Sanctuary
(c) Botanical Garden
(d) Sacred Grove
Answer – (c) Botanical Garden

14. The maximum growth rate occurs in :
(a) Stationary phase
(b) Senescent phase
(c) Lag phase
(d) Exponential phase
Answer – (d) Exponential phase

15. Organisms capable of maintaining constant body temperature are :
(a) Stenothermal
(b) Homeothermal
(c) Poikilothermal
(d) Conformers
Answer – (b) Homeothermal

16. Triploid tissue in angiosperms is :
(a) Nucellus
(b) Endosperm
(c) Endothecium
(d) Tapetum
Answer – (b) Endosperm

17. Pollen grains are well preserved as fossils because of the presence of :
(a) Sporopollenin
(b) Cellulose
(c) Lignocellulose
(d) Pecto-Cellulose
Answer – (a) Sporopollenin

18. The correct sequence of harmone secretion from the beginning of menstruation cycle is :
(a) FSH, Progesterone, Estrogen
(b) Estrogen, FSH, Progesterone
(c) FSH, Estrogen, Progesterone
(d) Estrogen, Progesterone, FSH
Answer – (c) FSH, Estrogen, Progesterone

19. The mode of action of the copper ions in an IUD is to :
(a) Increase the movement of sperms
(b) Decrease the movement of sperms
(c) Make the uterus unsuitable for implantation
(d) Make the cervix hostile to the sperms
Answer – (b) Decrease the movement of sperms

20. The term Nuclein for genetic material was used by :
(a) Mendel
(b) Franklin
(c) Meischer
(d) Chargaff
Answer – (c) Meischer

21. A woman has an “X” linked condition on one of her “X” chromosomes. This chromosomes can be inherited by :
(a) Only sons
(b) Only grand children
(c) Only daughter
(d) Both sons and daughters
Answer – (d) Both sons and daughters

22. The DNA finger printing pattern of child is :
(a) Exactly similar to both of the parents
(b) 100% similar to father’s DNA print
(c) 100% similar to the mother’s DNA print
(d) 50% bands similar to father and rest similar mother
Answer – (d) 50% bands similar to father and rest similar mother

23. What is the genetic disorder in which an individual has an overall masculine development gynecomastia and is sterile?
(a) Tuner’s syndrome
(b) Klinefelter’s syndrome
(c) Edward syndrome
(d) Down’s syndrome
Answer – (b) Klinefelter’s syndrome

24. Which type of selection is observed in industrial melanism in moth, Biston bitularia :
(a) Stabilising
(b) Directional
(c) Disruptive
(d) Artificial
Answer – (b) Directional

25. (p+q)² = p² + 2pq + q² = 1 Represents an equation used in :
(a) Population genetics
(b) Mendelian genetics
(c) Biometrics
(d) Molecular genetics
Answer – (a) Population genetics

26. Earthworm is a :
(a) Herbivore
(b) Secondary consumer
(c) Tertiary consumer
(d) Detrivore
Answer – (d) Detrivore

27. Secondary metabolites such as nicotine strychnine and caffeine are produced by plants for their :
(a) Nutritine value
(b) Growth response
(c) Defence action
(d) Effect on reproduction
Answer – (c) Defence action

28. The relationship when one species is harmed and other remain unaffected.
(a) Amensalism
(b) Predation
(c) Symbiosis
(d) Parasitism
Answer – (a) Amensalism

29. ………………. is not generally seen in biodiversity hotspots.
(a) Endemism
(b) Species richness
(c) Loss of diversity
(d) Lesser interspecific competition
Answer – (d) Lesser interspecific competition

30. The structure of bilobed anther consists of :
(a) 2 thecae, 2 sporangia
(b) 4 thecae, 4 sporangia
(c) 4 thecae, 2 sporangia
(d) 2 thecae, 4 sporangia
Answer – (d) 2 thecae, 4 sporangia

31. The thalamus contributes to the fruit formation in :
(a) Banana
(b) Orange
(c) Strawberry
(d) Guava
Answer – (c) Strawberry

32. What is present in the middle piece of sperm :
(a) Acrosome
(b) Mitochondria
(c) Nucleus
(d) Proximal centriole
Answer – (b) Mitochondria

33. A female undergoing IVF treatment has blocked fallopian tubes. The technique by which the embryo with more than 8 blastomeres will be transferred into the female for further development is :
(a) ZIFT
(b) GIFT
(c) IUT
(d) AI
Answer – (c) IUT

34. How many types of gametes would be produced if the genotype of a parent is AaBB?
(a) 1
(b) 2
(c) 3
(d) 4
Answer – (b) 2

35. In Antirrhinum, RR is phenotypically red flower rr is white and Rr is pink. Select the correct phenotypic ratio in F1 generation when a cross is performed between RR × Rr :
(a) 1 red : 2 pink : 1 white
(b) 2 pink : 1 white
(c) 2 red : 2 pink
(d) AU pink
Answer – (c) 2 red : 2 pink

36. Which of the following RNA is not required for the synthesis of protein?
(a) siRNA
(b) mRNA
(c) tRNA
(d) rRNA
Answer – (a) siRNA

37. AGGTATCGCAT is a sequence from the coding strand of a gene. What will be the corresponding sequence of the transcribed mRNA?
Answer – (c) AGGUAUCGCAU

38. How many mya, the jawless fish probably evolved?
(a) 320
(b) 350
(c) 400
(d) 500
Answer – (b) 350

39. Coelacanth was a :
(a) Invertebrate
(b) Fish
(c) Amphibian
(d) Reptile
Answer – (b) Fish

40. The amount of nutrients such as carbon, nitrogen, phosphorus and calcium present in the soil at any given time is referred as :
(a) Standing crop
(b) Climax
(c) Climax community
(d) Standing state
Answer – (d) Standing state

41. If a population of 50 paramecia present in a pool increase to 150 after an hour what would be the growth rate of population?
(a) 50 per hour
(b) 200 per hour
(c) 5 per hour
(d) 100 per hour
Answer – (d) 100 per hour

42. In the equation GPP-R=NPP, R represents :
(a) Respiration losses
(b) Radiant energy
(c) Retardation factor
(d) Environment factor
Answer – (a) Respiration losses

43. Which one of the following plants shows a very close relationship with a species of moth where none of the two can complete its life cycle without the other?
(a) Yucca
(b) Banana
(c) Hydrilla
(d) Viola
Answer – (a) Yucca

44. Pollen grain of which plant cause allergy :
(a) Parthenium
(b) Coriander
(c) Triticum
(d) None of these
Answer – (a) Parthenium

45. Cotyledon of maize grain is called :
(a) Plumule
(b) Coleorhiza
(c) Placenta
(d) Scutellum
Answer – (d) Scutellum

46. Androgens are synthesized by :
(a) Sertoli cells
(b) Leydig cells
(c) Seminal vesicles
(d) Bulbourethral gland
Answer – (b) Leydig cells

47. In which of the following techniques the embroys are transferred to assist those females who cannot conceive.
(a) ZIFT and IUT
(b) GIFT and ZIFT
(c) ICSI and ZIFT
(d) GIFT and ICSI
Answer – (a) ZIFT and IUT

48. A couple has two daughter. What is the probability that the third child will also be a female?
(a) 25%
(b) 50%
(c) 75%
(d) 100%
Answer – (b) 50%

49. Down’s syndrome is caused by an extra copy of chromosome number 21. What percentage of Offsprings produced by an affected mother and a normal father would be affected by this disorder?
(a) 50%
(b) 25%
(c) 100%
(d) 75%
Answer – (a) 50%

50. The experimental proof for semi conservative replication of DNA was first shown in a :
(a) Bacterium
(b) Plant
(c) Fungus
(d) Virus
Answer – (a) Bacterium

51. Fossils are generally found in :
(a) Sedimentary rocks
(b) Igneous rocks
(c) Metamorphic rocks
(d) Any type of rock
Answer – (a) Sedimentary rocks

52. Analogous organs arise due to :
(a) Divergent evolution
(b) Artificial selection
(c) Genetic drift
(d) Convergent evolution
Answer – (d) Convergent evolution

53. The rate of decomposition is faster in the ecosystem due to following factor except :
(a) Detritus richer in lignin and chitin
(b) Detritus rich in sugars
(c) Warm and moist environment
(d) Presence of aerobic soil microbes
Answer – (c) Warm and moist environment

54. Inspite of inter specific competition in nature which mechanism the competing species might have evolved for their survival?
(a) Predation
(b) Resource partitioning
(c) Competitive Release
(d) Mutualism
Answer – (b) Resource partitioning

55. A species which was introduced for ornamental value but has become a troublesome weed in India :
(a) Trapa spinosa
(b) Parthenium hysterophoru
(c) Eichhornia crassipes
(d) Prosopis juliflora
Answer – (c) Eichhornia crassipes

56. Choose the right one among the statements given below :
(a) IUDs are generally inserted by user herself.
(b) IUDs increase phagocytosis reaction in uterus.
(c) IUDs suppress gametogensis.
(d) IUDs once inserted need not be replaced
Answer – (b) IUDs increase phagocytosis reaction in uterus.

57. Hormones released by placenta are :
(a) hPL, hCG, oxytocin
(b) hCL, hPL, prolactin
(c) hCG, hPL, estrogen, progestrone
(d) hPL, hCG, estrogen, progestrone, relaxin
Answer – (d) hPL, hCG, estrogen, progestrone, relaxin

58. Test cross involves :
(a) crossing of F1 hybrid with a homozygous recessive genotype.
(b) crossing between F1 hybrids.
(c) crossing between two genotype with recessive traits.
(d) crossing between two genotype with dominant traits.
Answer – (a) crossing of F1 hybrid with a homozygous recessive genotype.

59. Human chromosomes with highest and least number of genes are :
(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

60. Evolutionary history of any organism is known as :
(a) Palaeontology
(b) Phylogeny
(c) Ontology
(d) Ancestry
Answer – (b) Phylogeny

61. AIDS is caused by HIV. HIV does not spread by which of the following mean :
(a) Transfusion of contaminated blood.
(b) Sharing of infected needles.
(c) Shaking hands with infected person.
(d) Sexual contact with infected person.
Answer – (c) Shaking hands with infected person.

62. An example of endomycorrhiza :
(a) Glomus
(b) Rhizobium
(c) Agaricus
(d) Nostoc
Answer – (a) Glomus

63. PCR is most useful in :
(a) DNA synthesis
(b) Protein synthesis
(c) DNA amplification
(d) Amino acid synthesis
Answer – (c) DNA amplification

64. A transgenic animal has :
(a) Foreign DNA in its cells
(b) Foreign RNA in its cells
(c) Foreign DNA in some of its cells
(d) Both (b) and (c)
Answer – (a) Foreign DNA in its cells

65. A protozoan reproduce by binary fission. What will be the number of protozoan after six generation :
(a) 24
(b) 128
(c) 64
(d) 32
Answer – (c) 64

66. Interaction between fig tree and wasp is :
(a) Parasitism
(b) Mutualism
(c) Commensalism
(d) Predation
Answer – (b) Mutualism

67. Red Data book contains :
(a) Useful plants
(b) Useful animals
(c) Endangered species
(d) Both (a) and (b)
Answer – (c) Endangered species

68. Which of the following is a false fruit :
(a) Banana
(b) Orange
(c) Apple
(d) Mango
Answer – (c) Apple

69. Sickle cell anemia is an example of :
(a) Point mutation
(b) Autosomal recessive disorder
(c) Mendelian disorder
(d) All of these
Answer – (d) All of these

70. Death rate is called :
(a) Mortality
(b) Emigration
(c) Inmigration
(d) Natality
Answer – (a) Mortality



Assertion-Reason Based Questions

These question consists of two statements each printed as Assertion and Reason. While answering these questions you are required to choose any one of the following responses.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.

1. Assertion (A) : Vaccination is also called preventive inoculation.
Reason (R) : A vaccine prevents the formation of antibodies inside the body.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer –(c) A is true and R is false.

2. Assertion (A) : DNA fingerprinting involves identifying differences in some specific regions DNA sequence.
Reason (R) : In repetitive DNA sequences a small stretch of DNA is repeated many times.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (b) Both A and R are true, R is not correct explanation of A.

3. Assertion (A) : Genetic engineering is essentially the alteration of the genetic make up of cells by deliberate and artificial means.
Reason (R) : It involves transfer or replacement of genes to create recombinant DNA.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (a) Both A and R are true, R is correct explanation of A.

4. Assertion (A) : BOD indicates the extent of water pollution by organic wastes.
Reason (R) : Increase in BOD decreases dissolved oxygen of waste water.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (b) Both A and R are true, R is not correct explanation of A.

5. Assertion (A) : Round worm is endoparasite of human intestine.
Reason (R) : Improperly cooked food is the source of intestinal infections.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (b) Both A and R are true, R is not correct explanation of A.

6. Assertion (A) : Antibodies have proved effective in lowering mortality rate.
Reason (R) : Antibodies are used for preservation of food like fresh meat, fish and poultry feed.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (c) A is true and R is false.

7. Assertion (A) : Discovery of penicillin by Alexander Fleming was a discovery by chance.
Reason (R) : Fleming was working on Penicilliumnotatum along with staphylococcus bacteria.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (c) A is true and R is false.

8. Assertion (A) : There is no chance of transmission of malaria to a man by the bite of a male Anopheles mosquito.
Reason (R) : It carries a non virulent strain of plasmodium.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (c) A is true and R is false.

9. Assertion (A) : Interferons are a type of antibodies produced by cells infected by bacteria.
Reason (R) : Interferons stimulate inflammation at the site of injury.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) Both A and R are false.
Answer – (d) Both A and R are false.

10. Assertion (A) : Insulin is a type of antibiotic
Reason (R) : It is synthesized by the process of fermentation.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) Both A and R are false.
Answer – (d) Both A and R are false.

11. Assertion (A) : Nitrogen fixing bacteria of legume nodules live in O2-depleted cells.
Reason (R) : Leghaemoglobin completely remove O2 from nodule cells.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (a) Both A and R are true, R is correct explanation of A.

12. Assertion (A) : A person who has received a cut and is bleeding needs to be given anti-tetanus treatment.
Reason (R) : Anti-tetanus injection provides immunity by introducing antibodies for tetanus.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (a) Both A and R are true, R is correct explanation of A.

13. Assertion (A) : ELISA is widely used for the detection of infectious diseases like AIDS
Reason (R) : ELISA is very sensitive and selective test and needs very small amount of reagents.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (b) Both A and R are true, R is not correct explanation of A.

14. Assertion (A) : Genetic engineering is also called Recombinant DNA technology.
Reason (R) : It brings about improvement of genetic make up of an organism.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (b) Both A and R are true, R is not correct explanation of A.

15. Assertion (A) : Baculo viruses are biocontrol agents of genus Nucloeopolyhedro virus.
Reason (R) : They are effective against plant pathogens.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (c) A is true and R is false.

16. Assertion (A) : Cannabinoids are drugs of abuse.
Reason (R) : They affect cardiovascular and central nervous system activity.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (a) Both A and R are true, R is correct explanation of A.

17. Assertion (A) : A community constitute the biotic component of ecosystem.
Reason (R) : Different type of organism’s i.e. plants and animals together makes a community.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (a) Both A and R are true, R is correct explanation of A.

18. Assertion (A) : Chemical pesticides are comparatively hazardous than biopesticides.
Reason (R) : Biopesticides degrade the environment quickly.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (c) A is true and R is false.

19. Assertion (A) : One gene one enzyme hypothesis is applicable universally.
Reason (R) : One enzyme may contain one and more than one polypeptide chains.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (d) A is false and R is true.

20. Assertion (A) : All the individuals of purelines are heterozygous.
Reason (R) : A heterozygous individual has two dissimilar forms of an allele.
(a) Both A and R are true, R is correct explanation of A.
(b) Both A and R are true, R is not correct explanation of A.
(c) A is true and R is false.
(d) A is false and R is true.
Answer – (d) A is false and R is true.



Subjective Questions

1. Write scientific name of fruit fly.
Answer – Drosophila melanogaster

2. Name the type of immunity the colostrum provides to a new born baby.
Answer – Passive immunity

3. Name a free living and a symbiotic bacterium that serve as bio fertilizer.
Answer – Free living Bacterium : Azospirillum, Azotobacter
Symbiotic bacterium : Rhizobium

4. Give full form of ELISA, on which principle it works.
Answer – Enzyme Linked Immuno Sorbent Assay.
Principle : Antigen antibody association.

5. DNA is better genetic material than RNA. Give two reasons.
Answer – DNA is better genetic material because It is chemically and structurally stable and It is undergoing slow changes that is required for evolution.

6. What is PCR.
Answer – Polymerase chain reaction (PCR) is a reaction carried in vitro to amplify the DNA or gene of interest and create its multiple copies. It involves three steps – Denaturation, annealing and extension.

7. What is megasporogenesis?
Answer – The process of formation megaspores from the megaspore mother cell is called as megasporogenesis.

8. What are plasmids?
Answer – Plasmids are extra nucleoid circular DNA present in bacteria which are useful in genetic engineering.

9. What is baker’s yeast? Give its application.
Answer – The strains of yeast used to make beer, bread, and wine come from the species of yeast called baker’s yeast or Saccharomyces cerevisiae. It’s responsible for the fermentation that makes beer alcoholic.

10. What is translation?
Answer – The process of formation of protein as per the information on mRNA is called as translation.

11. Name the plant source of the drug commonly called “Smack”. How does it affect the body of abuser.
Answer – Papaver somniferum.
It deprressant and slows down body functions.

12. Name the bacterium responsible for large holes seen in “Swiss Cheese”. What are those holes due to.
Answer – Propiunibacterium Sharmanii.
These holes are due to production of large amount of CO2.

13. What is the source of cyclosporin-A?
Answer – Trichoderma Polysporum

14. Name the first transgenic cow.
Answer – The first transgenic cow is Rosie.

15. What is pleiotropy?
Answer – In genetics, Pleiotropy is defined as the expression of multiple traits by a single gene.

16. What is spermatogenesis?
Answer – Spermatogenesis is the synthesis of sperms it takes place in testis.

17. What is oogenesis?
Answer – Oogenesis is the synthesis of egg it takes place in ovary.

18. Write a short note on in-situ conservation of bio-diversity .
Answer – Conservation in hot spot regions which leads to endemism.
• Conservation in Biosphere reserves national parks and wild life sanctuaries
• Conservation of sacred groves

19. Expand the name of enzyme ADA. Why is this enzyme essential in human body?
Answer – ADA means adenosine deaminase.
It is essential for production of immunity in human body.

20. Why tropics have greater species diversity ?
Answer – Tropics have greater amount of sunlight throughout the year. It has ample rainfall. It do not face any natural environmental disturbances, so it shows greater biodiversity.

21. Which is better method of conservation of biodiversity according to you in-situ or ex-situ ?
Answer – According to me in-situ conservation is better mode as it follows the conservation of organism in its natural condition so help to maintain the ecological balance in the biosphere.

22. What are interferons? How do interferons check infection of new cells?
Answer – Virus infected cells secrete proteins called interferons. Interferons protect non-infeeted cells from further viral infection.

23. Name the microbes used for production of :
(A) Lactic acid (B) Aceticacid
Answer – (A) Lactobacillus (B) Acetobacteracete

24. What is triple fusion? Name the nuclei involve in it.
Answer – Fusion of two polar nuclei and one male gamete is called triple fusion. It occurs in embryo sac.

25. Differentiate between benign tumour and malignant tumour.
Answer –

Benign Tumour Malignant Tumour
1. Remains confined to original location. 1. Invade and damage the surrounding normal tissues.
2. They are not cancerous. 2. They are cancerous.
3. The cells of this tumour are not metastatic. 3. The cells of this tumour are metastatic.
4. These are harmless. 4. These are harmful.


26. Differentiate between active and passive immunity.
Answer –

Active Immunity Passive Immunity
1. Immediate relief from ailment is not there. 1. Immediate relief from ailment.
2. Active role of sufferer in production of immunity. 2. Role of sufferer is not active.
3. Antibodies are produced on exposure to antigen. 3. Antibodies are injected.
4. Mother’s milk does not provide active immunity. 4. Mother’s milk provides passive immunity.


27. Name the enzyme produced by streptococcus bacterium. Explain its importance in medical science.
Answer – Streptokinase is produced by streptococcus.
It is a clot buster which removes clots from blood vessels of patients who have undergone myocardial infection leading to heart attack.

28. Write four advantages of GMO.
Answer – (i) More tolerant to abiotic stresses.
(ii) Reduce reliance on chemical pesticides.
(iii) Helped to reduce post harvest losses .
(iv) Increased efficiency of mineral usage by plants.

29. Differentiate between Genotype and Phenotype.
Answer : Genotype – Genetic composition for e.g Pure tall pea plant can be written as TT.
• Phenotype – Appearance of a living thing e.g Black colour of hair here black is Phenotype.

30. What is DNA polymorphism? Why is it important to study it?
Answer – DNA polymorphism, mean different forms of DNA i.e DNA of one organism is different form the other due to difference in repetitive DNA sequences.
Importance : Basis of genetic mapping and basis of DNA fingerprinting.

31. How do Darwin’s finches illustrate adaptive radiation?
Answer – Adaptive radiation means the process of evolution of different species in a given geographical area starting from a point literally radiating to other areas of habitat .
Darwin’s finches were originally seed eating but depending upon variety of habitats they evolved their beaks for insectivorous and vegetarian finches.

32. Why is haemophilia generally observed in human males? Explain the conditions under which a human female can be haemophilic.
Answer – Haemophila is sex linked recessive disease. The gene responsible for haemophilia is present on X chromosome. In males only one “X” chromosome is there, so if mutated gene is present on X chromosome then the male will certainly be sufferer.

33. Describe flow of energy in an ecosystem.
Answer – The flow of energy in ecosystem is unidirectional that is from producers to consumers it takes place by means of 10% law that is from one trophic level only 10% of energy is transferred to the next level, rest of the energy is either used in metabolic reactions of a particular trophic or dissipated as free energy in environment.

34. Write any three causes of Biodiversity loss.
Answer – Three cause of biodiversity loss are :
(i) Over use : Due to over exploitation by humans speices like passenger pigeon are extinct.
(ii) Habitat loss : Due to deforestation of forest some spices are extinct.
(iii) Invaison of alien species
(iv) Co-exctions

35. Differentiate between convergent and divergent evolution.
Answer –

Convergent Evolution Divergent Evolution
1. Structure of analogous organs show convergent evolution. 1. Structure of homologous organs show divergent evolution.
2. Example : Wings of birds Insects and Bat. 2. Example : Vertebrate fore-limbs.


36. Give three types of ecological pyramids with example of each type.
Answer – Pyramids are of three types :
(i) Pyramid of number – Always upright
(ii) Pyramid of Biommass – can be upright & inverted
(iii) Pyramid of energy – upright

37. Name the two types of immune systems in a human body. Why are they called so?
Answer – Cell mediated immunity because cells involved in production of immunity.
Humoral immunity because immunity producing antibodies are released in blood.

38. Write four feature of genetic code.
Answer – (i) Gentic code is triplet
(ii) It is specific and unambiguous
(iii) It is degenerate
(iv) It is universal and continuous

39. Write difference between homologous and analogous organs.
Answer : Homologous organs – Which are different in appearance but anatomically same for e.g forelimbs of vertebrates.
• Analogous organs – Which are similar in appearance but different in origin and anatomically e.g wings of insects and wings of birds.

40. What are anti biotics? Name the organism from which penicillin was first extracted.
Answer – Antibiotics are chemical compounds produeced by certain useful microbes and employed to kill certain harmful microbes.
Penicllin was extracted from the fungus Penicllium notatum.

41. What is test cross ? What can be its one use.
Answer – A cross which is used to access the genotype of an individual in it the individual to be tested is crossed with homozygous recessive parent if the progeny are showing only dominant feature then the parent (which was tested) is homozygous, if the progeny are showing both dominant and recessive feature it means the parent is homozygous.

42. Distinguish between Euchromatin and Heterochromatin.
Answer : Euchromatin – It is lightly stained and transcriptionally active.
• Heterochromatin – It is darkly stained and transcriptionally in active.

43. Explain the different modes of pollination that can occur in chasogamous flower.
Answer : Auto gamy – Transfer of pollen grains from anther to stigma of the same flower.
• Geitonogamy – Transfer of pollen grain from anther to stigma of the other flower on the same plant.
• Xenogamy – Transfer of pollen grain from anther to stigma of the other flower on the different plant.

44. Write different between grazing food chain and amd detritus food chain.
Answer – Grazing food chain starts with plants. The primary consumer are herbivore
• Detritus food chain starts with dead organic matter. The primary consumer are decompsers.

45. Write a short note on ex-situ conservation of biodiversity.
Answer – Ex-situ conservation is the technique of conservation of all levels of biological diversity outside their natural habitats through different techniques like zoo, captive breeding, aquarium, botanical garden, and gene bank.

46. Name the organic material found in exine layer of cell wall of pollen grain? Write down its advantage of it for pollen grain.
Answer – ‘Sporopollenin’ is found in exine layer of cell wall of pollen grain. Exine protect the pollen from dessication, acids and extreme weather condition thus increase its viability.

47. What is point mutation? Give example of it.
Answer – The mutation that is caused by addition, deletion or substitution of single base pair is called point mutation. Example: sickle cell anemia is caused by point mutation where single base substitution changes codon GAC to GUG.

48. Wings of a bird and wings of butterfly are either analogous or homologous organ? Also tell the kind of evolution they represent.
Answer – Wings of a bird and wings of butterfly are analogous organs. These show convergent evolution where different structures are evolved for same function.

49. What is GEAC? Write down its objectives.
Answer – GEAC refers to ‘Genetic Engineering Approval Committee’. GEAC made decision regarding validation of GMO research and safety of introducing these GMO for public service.

50. If we don’t follow genetic barriers while creating GMO, it can be dangerous. Do you agree with this statement ?
Answer – Yes, we agree with this statement as if genetic barriers are not used for creating GMO this can be dangerous as these organism can cause a threat to natural flora and fauna may lead to loss of biodiversity, cause ecological imbalance pose threat to our environment.

51. A person is advised antiretroviral therapy, which infection is he suffering from? Name the causative organism for this disorder.
Answer – The person may be affected by AIDS (Acquired Immuno Deficiency Syndrome). AIDS is caused by HIV-virus (Human immunodeficiency virus). It has RNA as genetic material i.e. it is a retrovirus.

52. Write in brief about ‘Implantation’.
Answer – After fertilization the zygote undergo cleavages in the oviduct and it forms 16 cells called blastomeres this stage is called morula. The morula continues to divide and transform in to blastocyst. In blastocyst outer layer of blastomeric form trophoblast and inner cell form inner cell mass. Trophoblast get attached to endometrium and after attachment the uterine cells divide rapidly so the blastocyst become embedded in endometrium this is called implantation.

53. Write in brief about ‘Male accessory ducts’.
Answer – Male accessory gland includes seminal vesicles prostate gland and bulbourethral glands. Secretion of these glands constitutes seminal plasma that has fructose calcium and may enzymes. Secretion of bulbourethral gland helps in lubrication of penis.

54. Why apomixis is preferred to produce seeds in hybrid crops?
Answer – Apomixis is preferred to produce seeds in hybrid crops as in this technique as :
• seeds are formed without fertilization so no segregation of useful character.
• cost and time of seed production is reduced.

55. Explain how XXY individuals can arise in human beings? Name the disorder and its symptoms?
Answer – XXY karyotype can be produced by gaining extra copy of X chromosome. This is known as Klinefelter Syndrome. Such individual are males with feminine characters like Gynaecomastia. They are generally sterile.

56. How Hugo De Vries theory of evolution differs from Darwin Theory of evolution?
Answer – Hugo De Vries believe in sudden or random mutation at large scale that cause speciation. He proposed saltation as basis of evolution.
On other hand Darwin theory of Natural selection is based on slow and inheritable mutation. These mutations form the basis of variation in population. Nature select the fittest organism.

57. Why diseases like Tuberclosis, cholera, typhoid spread more commonly in crowded areas?
Answer – T.B, Cholera are communicable diseases that spread via air, water so in crowded areas there transmission can happen easily.

58. What are vectors and pathogens?
Answer : Vectors – Vectors are the organisms like insects that help in transmission of the pathogen e.g. flies, mosquitoes etc.
Pathogens – Pathogens are diseases causing micro organisms e.g. Salmonella typhi that causes typhoid.

59. What is advantage of genetically synthesized insulin over traditionally synthesized insulin? Name the organism used to produce this insulin?
Answer – Genetically synthesized insulin does not cause allergy. Easy and economical production by rDNA technology. Insulin is produced by transgenic E.coli.

60. Name the nematode that infests the tobacco plant and the part that it infests.
Answer – Meloidegyne incognito (Roots)

61. How is Agrobacterium used to protect tobacco plant from this attack?
Answer – By using Agrobacterium vector nematode specific genes were introduced into host plant, introduction of DNA produce both sense and anti-sense strand of RNA that being complementary to each other, this ds RNA initiated RNAi and silenced the specific mRNA of nematode, hence parasite could not survive in host.

62. Which approach of biodiversity conservation do you feel is more comprehensive to understand the importance of biodiversity broad utilitarian or narrow utilitarian?
Answer – The broad utilitarian approach for biodiversity conservation is more comprehensive as it considers the ecological relationship between different communities hence give us a broader approach to understand the environment. For example, it helps to understand :
• the relationship of pollinator and plant
• relationship like predation and competition
• to maintain ecological balance
• relationship of forest with rainfall and soil erosion etc.

63. Explain Promoter.
Answer – The sequence that is located upstream means 5′ end of structural gene that provide binding site of RNA polymerase. The presence of promoter marks the template strand as it is present on template strand.

64. Explain Coding strand.
Answer – The strand of DNA that has polarity 5′ to 3′ is displaced during transcription and it does not code for RNA is called coding strand.

65. Explain Polymorphism.
Answer – Polymorphism is variation at genetic level due to mutation. These mutations in germ cell are inheritable. These mutations keep on accumulating and form the basis of polymorphism. When such inheritable mutation are observed in a population at high frequency this is called DNA polymorphism. Polymorphism may range from single nucleotide to large scale.

66. How are reporter enzyme help to monitor transformed cells in addition to selectable marker ?
Answer – The reporter gene help to select the transformant cells by insertional inactivation of the enzyme gene. For example, the insertional inactivation of enzyme β galactosidase in E.coli leads to formation of colourless colonies when grown on a chromogenic substrate while non transformant produce blue colonies.

67. Explain gel electrophoresis.
Answer : Gel electrophoresis – Process to separate the DNA fragments according to their molecular size by applying electric field across the agarose gel. DNA is negatively charged that will moves towards anode, smaller sized fragments move faster, fragments can be visualized under UV radiation as bright orange band due to dye Ethidium bromide. Desired DNA is obtained by elution process.

68. What is menstrual cycle? Explain the various phases of menstrual cycle.
Answer –

69. Draw a labelled diagram of bioreactor.
Answer –

70. Draw a labelled diagram of a typical anatropous ovule.
Answer –

71. Draw a well labeled diagrammatic sectional view of mammary gland.
Answer –

72. Describe the structure of a sperm with the help of labelled diagram.
Answer –

73. Why energy pyramids in a food chain are never inverted although pyramids of number can be inverted? Explain.
Answer – The energy that passes from one trophic level to next trophic level is only 10%. This is called 10% law of energy. So the amount of energy at first level will greater as compared to the energy at last tropic level that why energy pyramids are always upright.

74. What are the phases of menstrual cycle? What happens if an egg is fertilized ?
Answer – Three phases of menstrual cycle are :
(a) Menstrual phase –
• Discharge of mucous blood and endometrial lining through vagina.
• Occurs for 3-5days.
• Mark the start of menstrual cycle.
(b) Follicular phase –
• one of the primary follicles in ovary grows to mature Graafian follicle.
• Endometrium proliferate.
• Estrogen level increases and reaches the peak level in the middle of the cycle (14th day).
(c) Luteal phase –
• Gratian follicle rupture and ovum is released (ovulation).
• Corpus luteum formed to release progesterone.
• Endometrium continue to proliferate under effect of progesterone.
(d) If fertilization occurs it leads to implantation otherwise the unfertilized egg is released and it marks the beginning of another cycle.

75. What is semi conservative mode of replication? Explain Messelson and Stahl experiment to prove semi conservative replication ?
Answer – During DNA replication each newly synthesized DNA has one parental strand and one newly synthesized strand. This is called semi conservative replication. Since nitrogen is a part of DNA so Stahl and Messelson use heavy nitrogen in place of normal nitrogen
(a) Meselson and Stahl grew E.coli on heavy Nitrogen isotope for many generations. So that N¹⁵ is incorporated into its DNA. Then transferred E.coli to medium containing N¹⁴ and allow them to grow.
(b) The DNA in first generation has intermediate density as compared to parental DNA. The density was measured by cesium chloride density gradient method
(c) DNA in second generation has half normal density and half intermediate density DNA strand. This shows semi conservative replication.

76. Look at the diagram and identify the process. Explain the process and also write its applications.

Answer – The technique shown in picture is PCR (Polymerase chain reaction). PCR is used to amplify the DNA fragments of interest. DNA polymerase used in process is obtained from bacterium Thermophilus aquaticus that does not get denatured and polymerise at high temperature.
• Denaturation : heating of DNA at high temp (94-98° Celsius) to isolate both strands
• Annealing : annealing of primers for synthesis of new strands
• Extension : DNA polymerase binds to primer and polymerise new strands
• Detection of pathogenic micro organism
• Amplification of DNA
• in DNA analysis



Case Study Based Questions

1. A woman unable to conceive after many years of regular unprotected coitus went to specialised Infertility clinic. On complete examination woman has found to be normal while male partner was diagnosed with infertility. Male partner his unable to copulate the female. Couple was advised to opt for assisted reproductive technology (ART).
Questions :
(i) Name the technique which can be beneficial for the couple.
Answer – The technique which can be beneficial for the couple is GIFT.

(ii) What is meant by unprotected coitus.
Answer – Unprotected coitus means coitus without any intrauterine devices

(iii) What is the use IVF for the couple.
Answer – Since the male is unable to copulate, his sperms can be collected and used for in-vitro and the couple can have offsprings.


What is the cause of infertility in male in above case.
Answer – The male is not able to copulate, the sperms are not available for fertilisation so inspite of production of sperms the male is considered in fertile.

2. A group of teenagers was involved in drug abuse. They used syringes and needles to inject drugs. They indulged in this habit when they became adults. Administration of drugs through needles became a piece of cake for them. Raj was the most active drug abuser amongst them and use to take drugs in high profile parties. In a span of time he started losing weight and suffered Persistent Diarrhoea. He developed constant low grade fever and used to catch opportunistic infection. When he consulted a doctor he got himself tested for HIV in his blood and finally diagnosed with AIDS.
Questions :
(i) What is the cause of Raj’s weight loss?
Answer – The cause of Raj’s weight loss is that he is suffering from AIDS.

(ii) Is HIV a virus or bacteria.
Answer – HIV is virus.

(iii) Write the cause of AIDS.
Answer – The cause of AIDS are : Unprotected sex, Due to infected syringes, From suffering mother to foetus, Sex with multiple partners.


Write the symptoms of AIDS.
Answer – Weight loss and Inability to recover from infections.

3. X and Y are communicable disease whereas W and Z are non-communicable disease. X is transmitted through vectors whereas Y is transmitted through droplet infection. W is caused due to hormone deficiency whereas Z is a degenerative disease.
Questions :
(i) Give an example of Commiunicable disease and non-commiunicable disease.
Answer – Communicable disease : common cold
• Non-communicable disease : cancer

(ii) What is vector? Name a vector transmitted disease.
Answer – Vector is an animal in which a part of life cycle of pathogen is completed in it, female anaphloes mosquito a vector for malaria.

(iii) How wiil you differentiate between commiunicable and non-commiunicable disease.
Answer – Communicable disease are those which are transferred from the sufferer to a healthy person, for example covid.
While non-communicable disease is that which is not transferred from sufferer to healthy person, for example cancer.


Write the different modes of transmissions of commiunicable disease.
Answer – Different modes of transmission of a communicable disease are : Direct contact, in-direct contact

4. Aditya went to his hometown located in countryside along with his parents during the summer vacations. His grandparents house is surrounded by farmland from all sides lots of crops were growing nearby and Aditya was very excited to visit the crop fields. He seeked permission from his mother to play in farmland along with his friends and then went to play in the fields. On returning back he had running nose, watering eyes and continuous sneezing which was very frequent. The symptoms worsened with time.
Questions :
(i) What symptoms were observed when Aditya visited the crop fields?
Answer – The symptoms observed in Aditya when he visited the crop fields are running nose, watering eyes and continuous sneezing.

(ii) What is the cause of the symptoms Aditya was suffering from?
Answer – Aditya was hypersensitive towards the crop in the farmland.

(iii) How the symptoms can be over come?
Answer – The symptoms can be overcomed by avoiding the crop fields and by using anti allergic drugs.


Why Aditya suffred on visiting the farm land?
Answer – Aditya suffered on visiting the farmland because of oversensivity towards the allergens produced by the crop fields.

5. A technique known as amniocentesis is used to determine fetal abnormalities. This test based on the Chromosomal pattern in amniotic fluid. However this technique is legally banned now.
Questions :
(i) Name the blue coloured content in the figure.
Answer – The blue coloured contain in the figure is amniotic fluid.

(ii) The developing foetus is enclosed in ……………..
Answer – The developing foetus is enclosed in uterus.

(iii) Why the shown technique is banned.
Answer – The shown is banned because it is misused for detecting the sex of foetus.


What is the prime aim of this techinique.
Answer – The prime aim of this technique is to find out chromosomal abnormality.

6. Siddharth is a chain smoker. He got into this habit in early adolescence due to peer pressure and gradually got addicted to this habit. Its now almost 20 years, he is into the habit of smoking. Since few months, he is experiencing pain in chest, shortness of breath, wheezing and chronic cough with phlegm. He seeked advice of a medical practitioner who diagnosed with him lung cancer.
Questions :
(i) What is the cause of sufferings of Siddharth.
Answer – The cause of his suffering is his chain smoking nature.

(ii) Why Siddharth became a chain smoker.
Answer – Siddharth became chain smoker due to peer pressure.

(iii) What are the symptoms of Siddharth’s are sufferings.
Answer – The symptoms of his sufferings are pain in chest, shortness of breath wheezing and chronic cough.


Write the ill effect of chain smoking.
Answer – The ill effects of chain smoking are pain in chest, shortness of breath wheezing chronic cough.

7. Overall ability to fight the disease causing agents is called immunity. It is of two types. One is of non specific type and another is of specific type. Immune response in specific type of immunity is because of two type of lymphocytes. One of these cells produce protein bodies called antibodies which counteract the pathogen. When a host is exposed to antigen, antibodies are produced in its body. Preformed antibodies are administered to develop immunity in some cases. Sometime immune system shows exaggerated response to certain antigen. These antigens are called allergens.
Questions :
(i) What are interferons ?
Answer – Interferons are the proteins that activate the immune system and helps to destroy the tumors.

(ii) Name the anti body found in colostrum ?
Answer – Antibody IgG

(iii) Name the lymphocytes that produce antibodies ?
Answer – B lymphocytes produce antibodies. T lymphocytes help B lymphocyte to produce antibodies.


Differentiate between active immunity and passive immunity ?
Answer – Active immunity is based upon principle of antigen antibody reaction where organism produce antibody on interaction with antigen. Readymade antibodies are given to protect the body in passive immunity.

8. Reproductive Health refers to a total well being in all aspect of reproduction. i.e. physical, social, imotional and behavioral. Our nation was the first nation in the world to initiate various action plan at world level towards attaining reproductively healthy society. Counselling and creating awareness among people about reproductive organs,adolescence and associated changes, safe and hygienic sexual practices, sexually transmitted diseases is the primary step towards reproductive health. Providing facilities to control STDs, medical termination of pregnancy, birth control, infertility, delivery, post natal child and maternal management is another aspect of reproduction and child care health.
Questions :
(i) In which year the family planning programs were initiated ?
Answer – In year 1952

(ii) What do you think that awareness regarding reproductive health can help to prevent STDs ?
Answer – Awareness regarding reproductive health can help the individual to better understand the etiology of STDs, hence help him to protect from these.


Write major task of RCH programme.
Answer – The major task of RCH programme is to create awareness about a reproduction aspect and providing facilities for building a reproductively healthy society.

(iii) Name any STD.
Answer – Syphilis and Gonorrhea


HBSE Class 12th Biology Important Questions with Answer 2024


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