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

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PART A: BOTANY

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

1) In Maize, the chromosome number present in the meiocyte is 20. Give the number of chromosomes present in the following:

a. Maize pollen

b. Maize endosperm

✅ (a) 10 (b) 30

2) DNA fragments can be seen as bright orange-coloured bands when they are stained with ………………. and exposed to UV radiation.

✅ Ethidium bromide

3) Of the incident solar radiation, less than 50% is ……………….

✅ Photosynthetically active radiation (PAR).

4) Expand GEAC.

✅ Genetic Engineering Approval Committee

5) The expansion of distributional range of a species when the competing species is removed is called ……………….

✅ Competitive release.

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

6) Raju went to a Rice Research station on his study tour. There he noticed a scientist working on rice plants using scissors and forceps. To his surprise he saw the scientist covering the inflorescence with paper bags.

a. Name the techniques the scientist was doing.

b. Give the purpose of these techniques.

✅ Answer

(a) Emasculation and bagging for artificial hybridisation.

(b) Purpose of Emasculation: Removal of anthers from the bisexual flower bud of female parent before the anther dehisces.

Purpose of Bagging: Emasculated flowers are covered with a bag to prevent contamination of stigma with unwanted pollen.

7) Observe the diagram given below:

a. What does the given picture indicate?

b. In this process, three steps occur simultaneously. Name them.

✅ Answer

(a) Decomposition cycle in a terrestrial ecosystem

(b) Fragmentation, Leaching and catabolism.

8) In human beings, certain diseases are caused due to genetic disorders.

a. Name the method that allows the correction of a gene defect that has been diagnosed in a child or embryo.

b. How this method has been used for treating ADA (Adenosine deaminase) deficiency?

✅ Answer

(a) Gene therapy.

(b) Gene therapy for ADA deficiency: Collect lymphocytes from the patient’s blood and grow in a culture → Introduce a functional ADA cDNA into lymphocytes (using a retroviral vector) → return them to the patient.

9) Infection by nematodes causes threat to cultivation and yield loss of tobacco plants. A strategy has been developed at RNA level to control this infestation.

a. Name the process.

b. Explain how this process works at the molecular level.

✅ Answer

(a) RNA interference (RNAi) strategy.

(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.

10) What is meant by bioreactors? Name the most commonly used type of bioreactors.

✅ Answer

Bioreactors are the vessels in which raw materials are biologically converted to specific products, enzymes etc., using microbial, plant, animal or human cells. The most commonly used bioreactors are of stirring type (stirred-tank bioreactor).

11) In a marine ecosystem, a population of phytoplankton (150,000) supports a standing crop of fishes (40,000).

a. Draw the pyramid of biomass and

b. The pyramid of numbers in this ecosystem.

✅ Answer

12) Observe the diagram of enlarged view of a microsporangium showing wall layers. Label A, B, C & D.

✅ Answer

A= Endothecium

B= Middle layers

C= Microspore mother cells

D= Tapetum

13) Rashid isolated a natural plasmid from a bacterium and planning to facilitate cloning. What are the minimum requirements for considering the isolated plasmid as a vector?

✅ Answer

Origin of Replication (ori): This allows the plasmid to replicate independently within the host organism.

Selectable Marker: It allows for identification of transformed cells.

Multiple cloning Sites: It facilitates the insertion of foreign DNA.

14) Predators in nature are ‘prudent’. Explain.

✅ Answer

If a predator overexploits its prey, then the prey might become extinct. It results in the extinction of predator. Therefore, predators in nature are ‘prudent’.

15) Briefly explain Connell’s field experiments.

✅ Answer

Connell’s field experiments: On the rocky sea coasts of Scotland, there are 2 barnacle species: Balanus (larger & competitively superior) & Chthamalus (smaller).

Balanus dominates intertidal area and excludes Chthamalus. When Connell experimentally removed Balanus, Chthamalus colonized the intertidal zone.

16) Pond performs all the functions of an ecosystem. Justify.

✅ Answer

Pond performs all the functions of an ecosystem. For example,

• Autotrophs convert inorganic into organic material using solar radiant energy.

• Heterotrophs consume the autotrophs.

• Decomposition and mineralization of the dead matter to release them back for reuse by the autotrophs.

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

17) Copy the picture given below and mark the following:

a. Hilum

b. Funicle

c. Micropylar pole

d. Nucellus

e. Embryo sac

f. Chalazal pole

✅ Answer

18) Interspecific interaction arises from the interaction of populations of two different species. If we assign + for beneficial, - for detrimental and 0 for neutral interactions, copy and complete the following chart.

✅ Answer

19) Restriction endonucleases are the enzymes used to cut the DNA molecules.

a. Give the general terms for the specific sequences where these enzymes cut the DNA.

b. Name the enzyme that joins the foreign DNA and vector DNA.

c. Give any two procedures to introduce the recombinant DNA into the host cell.

✅ Answer

(a) Recognition sites or restriction sites.

(b) DNA ligase.

Biolistics (gene gun): In this, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA. This method is suitable for plants.

20) (a) What are the three critical research areas of biotechnology?

(b) Mention three options that can be thought for increasing food production.

✅ Answer

(a) Three critical research areas of biotechnology:

(i) Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.

(ii) Creating optimal conditions through engineering for a catalyst to act.

(iii) Downstream processing technologies to purify the protein/organic compound.

(b) Three options for increasing food production:

(i) agrochemical-based agriculture

(ii) organic agriculture

(iii) genetically engineered crop-based agriculture

PART B: ZOOLOGY

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

1) Note the relationship between the first pair and complete the second pair.

a. Natural selection: Darwin
Inheritance of acquired characters: …………

b. Heart of vertebrates: Homologous organs
Flippers of Penguin and Dolphin: ……………….

✅ a. Lamarck b. Analogous organs

2) Choose the odd one from the following and write the common features of others.

a. Estrogen b. Androgen

c. Relaxin d. Progesterone

✅ b. Androgen. Others are hormones present in female.

3) Identify the diagram and write how it acts.

✅ Copper T (CuT). It releases coper ions.

4) Expand the abbreviation UTRs.

✅ Untranslated Regions.

5) Morphine is extracted from latex of ……………….

✅ Papaver somniferum (poppy plant).

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

6) Complete the table using suitable terms.

✅ Answer

(a) 44A+X0

(b) Klinefelter’s syndrome

(d) Down’s syndrome

7) In pea plant the gene for yellow seed colour is dominant over green and round seed shape is dominant over wrinkled. Write the four types of gametes formed in a heterozygous pea plant with yellow and round seeds (YyRr).

✅ YR, Yr, yR and yr.

8) Arrange the following diseases in the following columns in a meaningful order.

Typhoid, Ringworms, Amoebiasis, AIDS, Malaria, Pneumonia, Common cold

✅ Answer

9) A transcription unit is given below. Observe it and answer the questions.

a. How can you identify the coding strand?

b. Write the sequence of RNA formed from this unit.

✅ Answer

(a) Coding strand would be in 5’→3’ direction.

(b) 5’-UCAGUACA-3’

10) In a class room discussion, a student argues that allergic reactions are more common in children of metro cities than in villages.

a. Do you agree with this statement?

b. Which type of immunoglobulin is responsible for allergic reactions?

c. Suggest two drugs which reduce allergic symptoms.

✅ Answer

(a) Yes. I agree.

(b) IgE type.

11) Match the columns B & C with respect to A.

✅ Answer

12) Some stages of the embryonic development are given below. Observe these diagrams and answer the questions.

a. What is A & B?

b. Which layer of blastocyst is attached to the endometrium? Name that process.

✅ Answer

(a) A= Blastomeres B= Morula

(b) Trophoblast. The process is called Implantation.

13) Distinguish between euchromatin and heterochromatin.

✅ Answer

• Euchromatin: Loosely packed and transcriptionally active region of chromatin. It stains light.

• Heterochromatin: Densely packed and inactive region of chromatin. It stains dark.

14) (a) State Hardy-Weinberg principle.

(b) What is meant by founder effect?

✅ Answer

(a) It states that allele frequencies in a population are stable and is constant from generation to generation in the absence of disturbing factors.

(b) The gene flow by chance causes change in frequency. Sometimes, the frequency change can lead to evolve into a different species. The original drifted population becomes founders. It is called founder effect.

15) Match the following:

✅ Answer

16) A collection of peppered moths made in England during different period is given below.

a. What is your observation?

b. Name the evolutionary process behind this phenomenon.

c. Write the reason for decreased number of white winged moth in 1920.

✅ Answer

(a) It denotes the variations in the number of white winged moths and dark winged moths in different periods.

(b) Natural selection.

(c) After industrialization (1920), the tree trunks became dark due to industrial smoke and soot. No growth of lichens. So white winged moths did not survive because the predators identified them easily. Dark winged moth survived because of suitable dark background.

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

17) The first child of a couple is affected with phenylketonuria. During the second pregnancy they visited a genetic counsellor and he prepared a pedigree chart of their family.

a. What is pedigree analysis?

b. Draw the symbols for

i. Normal male

ii. Affected female

iii. Sex unspecified

iv. Consanguineous mating

✅ Answer

(a) An analysis of genetic traits in several generations of a family is called pedigree analysis.

(b)

18) In E. coli, lactose catabolism is controlled by Lac operon. Lac operon in the absence of inducer (lactose) is given.

a. What is ‘P’?

b. Name the enzymes produced by the structural genes ‘Z’, ‘Y’ and ‘a’.

c. Redraw the diagram in the presence of an inducer.

✅ Answer

(a) Promoter.

(b) z gene: ꞵ-galactosidase,

y gene: permease

a gene: transacetylase

(c)

19) “STIs present a major health concern in both industrialized and developing countries.”

a. What do you mean by STIs?

b. Name two STIs.

c. Suggest two preventive measures.

✅ Answer

(a) Diseases or infections transmitted through sexual intercourse are called Sexually transmitted infections/ diseases (STDs or STIs).

(b) Gonorrhoea, syphilis, hepatitis-B, genital herpes etc.

• Always use condoms during coitus.

20) The given graph shows the distribution of insects in different latitudes of earth.

a. What is your observation?

b. List the three reasons for greater biodiversity in tropical regions.

c. Write two causes of biodiversity losses.

✅ Answer

(a) Insect species diversity decreases from the equator to the poles.

(b) Biodiversity (species richness) is highest in tropics because

• Tropics had more evolutionary time.

• Relatively constant environment (less seasonal).

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

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Plus Two Biology (Bot + Zoo) | Practice Model Question Paper PDF with Answer key | SET 5