Plus Two Biology (Bot + Zoo) | Practice Model Question Paper PDF with Answer key | SET 7

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PART A: BOTANY

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

1) After syngamy and triple fusion in embryo sac, embryo will be diploid and ……………… will be triploid.

✅ Endosperm

2) Natural interlinked food chains are called ……………….

✅ Food web

3) Fill in the blank:

Alpha I-antitrypsin is used to treat the disease ...............

✅ Emphysema

4) Write the name of technique used to remove the DNA from the gel.

✅ Elution

5) Note the relationship of first pair and fill up the blank suitably.

Mortality: No. of deaths in the population during a given period.

……………….: No. of births in the population during a given period.

✅ Natality

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

6) Write any three parts of a monocot embryo and write one peculiarity of each of these three parts.

✅ Answer

Scutellum: Single cotyledon.

Radicle: Lower end of the embryonal axis.

Coleorhiza: Sheath that encloses radicle.

7) A list of organisms is given. Place them in different trophic levels.

Grass, Man, Fishes, Birds, Lion, Grasshopper, Zooplankton, Trees

✅ Answer

• First trophic level (Producers): Grass, Trees

• Second trophic level (Primary Consumers): Grasshopper, Zooplankton

• Third trophic level (Secondary Consumers): Birds, Fishes

• Fourth trophic level (Tertiary Consumers): Lion, Man

8) Name the interaction between sea anemone and clown fish. Justify your answer with suitable explanation.

✅ Answer

Name of the interaction: Commensalism.

Clown fish protection from predators because predators stay away from the stinging tentacles of sea anemone. But sea anemone does not get any benefit from clown fish.

9) How does the inactive protoxin of Bacillus thuringiensis gets converted into active toxin when an insect ingests it?

✅ Answer

When an insect ingests the toxin, it becomes active due to alkaline pH of the gut which solubilise the crystals. Toxin binds to surface of epithelial cells creating pores. It causes death of the insect.

10) Synergids have a special cellular thickening at micropylar tip. Write the name of name and function of the structure.

✅ Answer

Filiform apparatus. It guides pollen tube into the synergids.

11) A biologist studied the population of rats in a barn.

He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30.

Calculate the net increase in population with suitable explanation.

✅ Answer

The net increase in population can be calculated as follows:

Net Increase= (Natality + Immigration) − (Mortality + Emigration)

Substituting the given values:

Net Increase= (250 + 20) − (240 + 30) = 0

So net increase in population is zero.

12) Given below is a data showing number of individuals and dry weight of different trophic levels in a grassland ecosystem. Construct,

a. Pyramid of number.

b. Pyramid of biomass.

✅ Answer

(a) Pyramid of number:

(b) Pyramid of biomass:

13) Many countries encourage the cultivation of Genetically Modified Crops (G. M. Plants). Write any two advantages of GM plants.

✅ Answer

GM plants are

a. Tolerant to abiotic stresses.

b. Pest resistant

14) Match the items of column A with B:

✅ Answer

15) Pyramid of energy is never been inverted. Why?

✅ Answer

When energy flows from a trophic level to the next higher trophic level, some energy is always lost as heat at each step.

16) Restriction endonuclease recognises a specific sequence in the DNA. Name that sequence and write its peculiarity.

✅ Answer

Palindromic nucleotide sequence.

Peculiarity: It is a sequence of base pairs that read the same on the two strands in 5' → 3' direction and in 3' → 5' direction.

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

17) Read the statements below and identify the mode of interaction between the species.

a. Tiger eating deer

b. Butterfly feeding pollen

c. Human liver fluke feed on snail

d. Lice on humans

e. Orchid attached to a tree

f. Mycorrhizal association of fungi and roots of higher plants

g. Sparrow eating seed

h. Egrets foraging close to cattle

✅ Answer

Modes of interaction:

a. Predation

b. Mutualism

c. Parasitism

d. Parasitism

e. Commensalism

f. Mutualism

g. Predation

h. Commensalism

18) A novel strategy to prevent nematode manifestation is based on ‘RNA interference’.

a. Explain RNA interference.

b. Can you suggest how it can be used for producing nematode resistant plant?

✅ Answer

(a) RNAi is a method of cellular defense in all eukaryotic organisms. It prevents translation of a specific mRNA (silencing) due to a complementary dsRNA molecule.

(b) Isolate Nematode-specific genes (DNA) and introduce into host plant using Agrobacterium vectors. It produces both sense & anti-sense RNA in host cells. These RNAs are complementary. So they form double stranded (ds) RNA. It initiates RNAi and silences the specific mRNA of nematode. Thus the parasite cannot survive in a transgenic host expressing specific interfering RNA.

19) Observe the diagram given below:

a. Identify the diagram and the parts A, B and C.

b. Briefly explain the applications of this technique.

✅ Answer

(a) It is the diagrammatic representation of recombinant DNA technology.

A= Vector DNA (plasmid)

B= Recombinant DNA molecule

C= Transformation

(b) It has applications in the field of agriculture (e.g., Bt cotton), medicine (e.g., genetically engineered insulin), transgenic animals etc.

20) Flowering plants evolved an array of adaptations to achieve pollination.

a. Explain 3 types of pollination.

b. Illustrate pollination in Vallisnaria.

✅ Answer

(a) 3 types of pollination:

• Autogamy: Transfer of pollen grains from the anther to the stigma of the same flower.

• Geitonogamy: Transfer of pollen grains from the anther to the stigma of another flower of the same plant.

• Xenogamy: Transfer of pollen grains from the anther to the stigma of a different plant.

(b) Pollination in Vallisnaria:

In Vallisneria, the female flower reaches the surface of water by the long stalk and the male flowers or pollen grains are released on to the surface of water. They are carried by water currents and reach the female flowers.

PART B: ZOOLOGY

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

1) Observe the relationship between first pair and write the missing one.

Menstrual phase: 1-5^th day

Ovulatory phase: ……………….

✅ 14^th day

2) Name the non-steroidal, once in a week pill developed by CDRI.

✅ Saheli

3) In a DNA sample, adenine is 22%. Find out the percentage of guanine.

✅ 28%

4) Name the confirmatory test for typhoid fever.

✅ Widal test

5) According to Global estimate of ………………., about 7 million species would have on earth.

a. Robert May

b. David Tilman

c. Edward Wilson

d. Alexander von Humboldt

✅ a. Robert May

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

6) (a) Complete the flow chart.

(b) What is the role of LH in female reproductive system?

✅ Answer

(a) A= FSH        B= Leydig cells.

(b) LH induces rupture of Graafian follicle and thereby ovulation.

7) India achieved a lot in reproductive health through RCH programme.

a. Expand RCH.

b. Write any 2 objectives of RCH programme.

✅ Answer

(a) Reproductive and Child Health care programme.

(b) ▪ Give awareness to people about reproduction related aspects for creating a reproductively healthy society.

▪ Educate about birth control, care of pregnant mothers, post-natal care of mother & child etc.

8) Haemophilia is more common in males than in females. Justify.

✅ Answer

Haemophilia is X -linked disease. In females, haemophilia is very rare because it happens only when mother is at least carrier and father haemophilic. But in case of males, there is only one X chromosome.

9) Two Pedigree charts are given below. Name the types of genetic traits shown in A & B and give suitable example for each.

✅ Answer

(A) Autosomal dominant trait. E.g. Myotonic dystrophy.

(B) Autosomal recessive trait. E.g. Sickle-cell anaemia.

10) Name the schematic structure and label A, B & C:

✅ Answer

Transcription unit.

A= Promoter

B= Terminator

C= Coding strand.

11) (a) Expand the term HGP.

(b) Name the two methodologies of HGP.

✅ Answer

(a) Human Genome Project.

(b) Expressed Sequence Tags (ESTs), Sequence Annotation.

12) p²+2pq+q²=1 is a binomial expression regarding an evolutionary principle.

a. Name the evolutionary principle.

b. Name any two factors affecting this evolutionary principle.

✅ Answer

(a) Hardy-Weinberg principle.

(b) Gene migration, Genetic drift, Mutation, Genetic recombination, Natural selection (Any two).

13) Name 2 examples for evolution due to anthropogenic action.

✅ Answer

Industrial melanism. Development of resistant varieties in organisms against herbicides, pesticides, antibiotics or drugs etc.

14) Fill in the blanks:

✅ Answer

(A) Cellular barrier.

(B) Cytokine barrier.

(C) Skin, Mucus coating.

(D) Gastric HCl, saliva, tear etc.

15) In sewage treatment plants, the Secondary treatment is also known as biological treatment. Write the steps involved in it.

✅ Answer

Primary effluent → Aeration tank → Action of flocs → BOD decreases → Settling tank → Effluent to water bodies → Sedimentation of flocs (activated sludge) → Anaerobic sludge digesters

16) When we move towards polar regions from tropical regions there is a gradual decrease in biodiversity. Give two reasons for this.

✅ Answer

Biodiversity (species richness) is higher in tropics than polar or temperate regions because

a. Tropics had more evolutionary time.

b. Relatively constant environment (less seasonal).

c. They receive more solar energy which contributes to greater productivity.

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

17) Placenta act as a physiological connection between mother and foetus.

a. Write any 2 functions of Placenta other than hormone secretion.

b. Name the placental hormones.

✅ Answer

(a) Supply O2, nutrients etc. from mother to foetus.

Remove CO2 and excretory wastes from foetus.

(b) Human chorionic gonadotropin (hCG), human placental lactogen (hPL), oestrogens, progesterone & relaxin.

18) Fill the columns appropriately.

✅ Answer

A= Down’s syndrome.

B= Short statured with small round head etc.

C= Klinefelter’s syndrome

D= 44 A + XXY

E= 44 A + X0

F= Sterile, Ovaries are rudimentary etc.

19) Diagram of lac operon is given:

a. Name the inducer of lac operon.

b. Redraw the lac operon in presence of inducer.

✅ Answer

(a) Lactose.

(b) Lac operon in presence of inducer:

20) (a) Carcinogens are cancer causing agents. Write different types of carcinogens.

(b) What is meant by metastasis?

✅ Answer

(a) Physical agents: E.g. Ionizing radiations like X-rays and gamma rays and non-ionizing radiations.

Chemical agents: Tobacco smoke, vinyl chloride, nicotine etc.

Biological agents: E.g. oncogenic viruses, c-onc (cellular oncogenes) etc.

(b) Cells sloughed from tumours reach other sites via blood where they form a new tumour. It is called metastasis.

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