Plus 2 Biology Question Paper (PDF) with Answers

Biology Model Exam SET 2023

SECOND YEAR HIGHER SECONDARY
MODEL EXAMINATION, FEBRUARY 2023

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PART A: BOTANY

I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3 x 1=3)

01. Choose the correct answer. The innermost wall layer of microsporangium that gives nutrition to pollen grain is called:

(a) Epidermis

(b) Endothecium

(d) Middle layer

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✅ (c) Tapetum

02. Name the first transgenic cow that produced human protein enriched milk.

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✅ Rosie

03. Fill in the blank: The natural interconnection of different food chains is called ……….

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✅ Food web

04. Choose the correct answer. Which of these enzymes removes nucleotides from the ends of a DNA?

(a) Exonuclease

(b) Endonuclease

(d) DNA Polymerase

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✅ (a) Exonuclease

05. Fill in the blank: The population interaction in which one species is harmed whereas the other is unaffected is known as ……….

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✅ Amensalism

II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9 X 2 = 18)

06. Write two roles of Predators in an ecosystem.

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✅ Answer:

1. They keep prey populations under control.

2. They help in maintaining species diversity by reducing competition among prey species.

07. (a) What is emasculation?

(b) Write the significance of this step in Artificial hybridization.

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✅ Answer:

(a) The removal of anthers from the flower bud before they dehisce using a pair of forceps.

(b) It prevents self-pollination in the female parent.

08. Bt-toxin does not kill Bacillus, but it kills insects. Write the reason.

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✅ Answer:

In Bacillus, the Bt-toxin exists as an inactive protoxin. In the insect gut, the alkaline pH solubilizes the crystals and converts the protoxin into its active form, which kills the insect.

09. (a) Write the name of the ecological pyramid given in the figure.

(b) This pyramid is always upright. Why?

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✅ Answer:

(a) Pyramid of Energy.

(b) According to the 10% law, only a small fraction of energy is transferred to the next trophic level, as most of it is lost as heat. Thus, energy at a lower level is always higher than at a higher level.

10. How can we visualize DNA fragments in Gel electrophoresis?

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✅ Answer:

By staining the DNA with Ethidium bromide and exposing it to UV radiation. The fragments appear as bright orange-colored bands.

11. (a) Expand ELISA.

(b) What is the principle of this process?

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✅ Answer:

(a) Enzyme-Linked Immunosorbent Assay.

(b) It is based on the principle of Antigen-Antibody interaction.

12. Observe the figure of Monocot seed and label the parts marked as A, B, C & D.

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✅ Answer:

A: Endosperm

B: Scutellum

C: Plumule

D: Radicle

13. Write the difference between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP).

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✅ Answer:

Gross Primary Productivity (GPP): The total rate of production of organic matter during photosynthesis.

Net Primary Productivity (NPP): The biomass available for the consumption of heterotrophs. It is calculated as NPP = GPP - R (where R is respiration loss).

14. Nₜ₊₁ = Nₜ + [(B + I) - (D + E)] is the equation to find the population density at a given time. What does B, I, D and E stand for?

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✅ Answer:

B: Natality (Birth rate)

I: Immigration

D: Mortality (Death rate)

E: Emigration

15. (a) Which enzymes are known as ‘molecular scissors’?

(b) What is the use of these enzymes in Genetic engineering?

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✅ Answer:

(a) Restriction enzymes (Restriction endonucleases).

(b) They are used to cut DNA at specific base sequences to create recombinant DNA.

16. Match the following:

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✅ Answer:

Fragmentation: Breakdown of detritus into smaller particles.

Leaching: Water soluble inorganic nutrients go down into the soil.

Catabolism: Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.

Mineralisation: Formation of inorganic nutrients from humus.

III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3 X 3 = 9)

17. (a) Observe the figure and write the name of two population growth curves marked as A & B.

(b) What does K and r stands for?

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✅ Answer:

(a) A: Exponential growth curve. B: Logistic growth curve.

(b) K: Carrying capacity. r: Intrinsic rate of natural increase.

18. Write three adaptations of insect pollinated flowers.

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✅ Answer:

• Flowers are large, colorful, and fragrant to attract insects.

• They produce nectar as a floral reward.

• Pollen grains are generally sticky.

19. (a) Write the name of the process given in the figure.

(b) What is the purpose of this process in rDNA technology?

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✅ Answer:

(a) PCR (Polymerase Chain Reaction).

(b) To amplify (make multiple copies of) a specific gene of interest.

20. Write three uses of Transgenic animals.

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✅ Answer:

• To study the normal physiology and development of the body.

• To test the safety of vaccines (e.g., polio vaccine).

• To produce biological products like human protein (α-1-antitrypsin).

PART B: ZOOLOGY

I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3 x 1=3)

01. Write the part of fallopian tube where fertilization takes place in human beings.

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✅ Ampullary region.

02. Select the completely curable sexually transmitted infections (STIs) from the following:

Genital herpes, Syphilis, Chlamydiasis, Hepatitis - B

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✅ Syphilis and Chlamydiasis.

03. Observe the given figure showing global magnitude of biodiversity in vertebrates. Identify the group of animals labelled as A.

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✅ Fishes.

04. Expand: (a) UTR (b) VNTR

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✅ (a) Untranslated Regions.

(b) Variable Number of Tandem Repeats.

05. Identify the first word pair relationship and fill the blank with suitable word for second pair.

Opioid receptors: Gastro intestinal tract

Cannabinoid receptors: ...................

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✅ Brain (Central Nervous System).

II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9 X 2 = 18)

06. (a) Define placenta.

(b) Write any 2 hormones secreted from placenta.

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✅ Answer:

(a) A structural and functional unit between the developing embryo (foetus) and the maternal body.

(b) hCG (human Chorionic Gonadotropin) and hPL (human Placental Lactogen).

07. Biodiversity loss is dangerous threat facing planet earth in present days. Write the four reasons of Biodiversity loss given as evil quartet.

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✅ Answer:

(a) Habitat loss and fragmentation.

(b) Over-exploitation.

(d) Co-extinctions.

08. (a) Define homologous organs.

(b) Analogous structures are a result of the ................... evolution.

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✅ Answer:

(a) These are the organs which have fundamental similarities in structure and origin but perform different functions.

(b) Convergent.

09. Name the microbes which produce the following bioactive molecules and write use of (a) and (b).

(a) Cyclosporin A

(b) Statin

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✅ Answer:

(a) Produced by Trichoderma polysporum. Use: Immunosuppressive agent in organ-transplant patients.

(b) Produced by Monascus purpureus. Use: Blood-cholesterol lowering agent.

10. Compete the table by filling (A) and (B).

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✅ Answer:

(A) Tubectomy.

(B) IUDs (Intrauterine Devices).

11. Identify the given symbols of Pedigree.

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✅ Answer:

(a) Male

(b) Female

(d) Mating between relatives (Consanguineous mating).

12. (a) Identify the given structure.

(b) Name (A) and (B).

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✅ Answer:

(a) Nucleosome.

(b) (A) DNA (B) Histone octamer.

13. Complete the given representation:

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✅ Answer:

(A) Skin / Mucus coating.

(B) Physiological barriers.

(D) Cytokine barriers.

14. (a) A man with blood group ‘AB’ marries a woman with blood group ‘O’. Write the possible genotypes of blood groups AB and O.

(b) Write the possible genotypes of their offspring by using Punnett Square.

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✅ Answer:

(a) Genotype of Blood Group AB: IᴬIᴮ

Genotype of Blood Group O: ii.

(b) The offspring will have genotypes Iᴬi (Blood Group A) and Iᴮi (Blood Group B).

15. Match the following: (George Gamow, Alec Jeffreys, Frederick Griffith, Taylor and Colleagues)

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✅ Answer:

George Gamow: Genetic Code.

Alec Jeffreys: DNA fingerprinting.

Frederick Griffith: Transformation experiment.

Taylor and Colleagues: DNA replication.

16. Using the given terms in brackets complete the evolutionary stages of man:

(Modern man, Ramapithecus, Homo erectus, Neanderthal man)

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✅ Answer:

(A) Ramapithecus

(B) Homo erectus

(D) Modern man

III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3 X 3 = 9)

17. (a) Name the embryonic stages in figure A and B.

(b) In figure B outer layer is trophoblast, and inner group of cells attached to trophoblast is ……….

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✅ Answer:

(a) A – Morula; B – Blastocyst.

(b) Inner cell mass.

18. (a) Complete the given representation: DNA → (A) → RNA → (B) → Protein.

(b) Categoric the following bases into Purines and Pyrimidines: Adenine, Cytosine, Uracil, Guanine.

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✅ Answer:

(a) (A) Transcription; (B) Translation.

(b) Purines: Adenine, Guanine

Pyrimidines: Cytosine, Uracil

19. (a) Cancer causing agents are called ……….

(b) Differentiate between benign tumour and malignant tumour.

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✅ Answer:

(a) Carcinogens.

(b) Benign tumours remain confined to their original location and do not spread; Malignant tumours are masses of proliferating cells that invade and damage surrounding tissues (metastasis).

20. (a) Identify and write genetic disorder in (A), (B) and (C).

(b) Write any three Mendelian disorders.

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✅ Answer:

(a) (A) Down's syndrome; (B) Klinefelter's syndrome; (C) Turner's syndrome.

(b) Haemophilia, Sickle-cell anaemia, and Color blindness.

Plus 2 Biology Question Paper (PDF) with Answers | 2023 March Model Exam