PART – A

I. Select the correct alternative from the choices given below:

1 x 15 = 15

1. Select the correct sequence of events in microsporogenesis

a) Sporogenous tissue → Microspore mother cell → Microspore tetrad → Microspores

b) Microspores → Microspore mother cell → Microspore tetrad → Sporogenous tissue

c) Sporogenous tissue → Microspore tetrad → Microspores → Microspore mother cell

d) Microspores → Sporogenous tissue → Microspore tetrad → Microspore mother cell

Ans: a) Sporogenous tissue → Microspore mother cell → Microspore tetrad → Microspores

2. Statement I: The process of release of sperms from the seminiferous tubule is called spermatogenesis.

Statement II: The spermatids are transformed into spermatozoa by the process called spermiogensis.

Choose the correct answer from the options given below:

a) Both statement I and statement II are correct

b) Both statement I and statement II are incorrect

c) Statement I is correct but statement II is incorrect

d) Statement I is incorrect but statement II is correct

Ans: d) Statement I is incorrect but statement II is correct

3. The function of myometrium layer present in the uterine wall is to

a) Undergo cyclical changes during menstrual cycle.

b) Exhibit strong uterine contraction during parturition.

c) Give protection to the uterus.

d) Help in the implantation process.

Ans: b) Exhibit strong uterine contraction during parturition.

4. The ________ hormone is secreted by the ovary in the later phase of pregnancy.

a) Androgens

b) Estrogens

c) Relaxin

d) Progestogens

Ans: c) Relaxin

5. Sperms produced by the seminiferous tubules are transported through accessory ducts. Which duct should be tied and cut for male sterilization?

a) Vas deferens

b) Vasa efferentia

c) Rete testis

d) Epididymis

Ans: a) Vas deferens

6. Reasons for human population explosion are given below:

i) Rapid decline in maternal mortality rate.

ii) Rapid decline in infant mortality rate.

iii) Rapid increase in death rate.

iv) Increase in the number of people in reproducible age.

Select the correct answer statements from the options given below:

a) i), ii) and iii) only

b) i) and ii) only

c) i), ii) and iv) only

d) iii) and iv) only

Ans: c) i), ii) and iv) only

7. In a dihybrid cross in pea plants, Mendel got 9:3:3:1 phenotypic ratio. It denotes that

a) The alleles of two genes are interacting with each other.

b) It is a polygenic inheritance.

c) It is a multiple allelic inheritance.

d) The alleles of two genes are segregating independently.

Ans: b) It is a polygenic inheritance.

8. A DNA segment has a total of 1000 nucleotides, out of which 240 of them are adenine containing nucleotides. How many pyrimidines bases this DNA segement possesses?

a) 480

b) 500

c) 760

d) 260

Ans: b) 500

9.  (p + q)2 = p2 + 2pq + q2 represents an equation used in:

a) Population genetics

c) Molecular genetics

b) Mendelian genetics

d) Biometrics

Ans: a) Population genetics

10. A farmer working in a field was bitten by poisonous snake. Doctor gave him an antivenom treatment that contain preformed antibodies. This type of immunisation is known as

a) Autoimmunity

b) Passive immunisation

c) Innate immunity

d) Active immunisation

Ans: b) Passive immunisation

11. An agriculture labour was spraying some powder mixed with water onto fruit trees to get rid of insect larvae. Which of the following biocontrol agent could have been used here?

a) Bacillus thuringiensis

b) Trichoderma

c) Dragonflies

d) Ladybird

Ans: a) Bacillus thuringiensis

12. Choose the correct sequence of polymerase chain reaction steps from the following:

a) Annealing → Denaturation → Extension

b) Extension → Annealing → Denaturation

c) Denaturation → Extension → Annealing

d) Denaturation → Annealing → Extension

Ans: d) Denaturation → Annealing → Extension

13. Use of bioresources by multinational companies and other organisations without proper authorisation and compensatory payment is referred as

a) Biopiracy

b) Biofortification

c) Bioprospecting

d) Bioprocessing

Ans: a) Biopiracy

14. An example for ex situ conservation is

a) National parks

b) Sacred groves

c) Biosphere reserves

d) Zoological parks

Ans: d) Zoological parks

15. The graph given below shows species-area relationships. 

Which of the following equation correctly represent the curve?

a) S = CAZ

b) Log S= log C + Z log A

c) Bioprospecting

d) Log Z = log C + S log A

Ans: a) S = CAZ

II. Fill in the blanks by choosing the appropriate word/Words from those given below:

1 x 5 = 5

(Primary productivity, Coelacanth, Secondary productivity, Glomus, Amniocentesis, Plasmid)

16. Statutory ban on amniocentesis is required to check increasing female foeticides.

17. A fish thought to be extinct and caught in South Africa in 1938 is Coelacanth.

18. An example for mycorrhiza forming fungi is Glomus.

19. Autonomously replicating circular extra-chromosomal DNA of bacteria is known as Plasmid.

20. Rate of formation of new organic matter by consumers is referred as Secondary productivity.

PART - B

III. Answer any FIVE of the following questions in 3 – 5 sentences wherever applicable:

2 x 5 = 10

21. Differentiate between geitonogamy and xenogamy. 

22. Write a short note on sex determination method in birds.

Ans: 

Sex determination in birds – ZZ – ZW method.

In birds, males produce sperms of only one type i.e. ZZ – male homogametic. All sperms will have Z chromosome.

Females produce ova of two different type i.e. ZW – female heterogametic.

50% ova with Z chromosome and another 50% ova with W chromosome. Hence they show Female heterogamety. Sex of the new born depends on the type gametes are involved in fertilization.

23. Mention the levels where gene expression can be regulated in eukaryotes.

Ans: 

1. Transcriptional level (formation of primary transcript),

2. Processing level (regulation of splicing),

3. Transport of mRNA from nucleus to the cytoplasm,

4. Translational level.

   
   

24. Write a short note on Neanderthal man.

Ans:

• The Neanderthal man with a brain size of 1400cc.

• Lived in near east and central Asia between 1,00,000-40,000 years back.

•  They used hides to protect their body and buried their dead.

25. Draw the structure of an antibody molecule.

Ans:

26. Write the functions of genes cryIAb and cryIIAb.

Ans:  The toxin is coded by a gene named cry.  The proteins encoded by the genes,

cryIAc and cryIIAb - control the cotton bollworms, and

cryIAb controls - corn borer.

27. Briefly explain the significance of David Tilman’s long-term ecosystem experiments using outdoor plots. 

Ans: Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity.

PART - C

IV. Answer any FIVE of the following questions in 40 – 80 words each wherever applicable:

3 x 5 = 15

28. Draw a L.S. of grass embryo diagram and label the following parts:

a) Scutellum b) Coleoptile c) Shoot apex d) Radicle e) Root cap f) Coleorrhiza

Ans:

29. In the figure given below, parts A and B show the level of hormones which influence the menstrual cycle. Study the figure and answer the questions that follow:

a) Name the organs/glands which secrete the hormones represented in labelled parts A and B. (1M)

b) State the role of hormones secreted from part B on the uterus of human female during menstrual cycle. (2M)

Ans: 

a) Part A - Both FSH and LH are secreted by anterior pituitary.

Part B - Estrogen and Progesterone are secreted by the ovary (Estrogen - Ovarian follicles, Progestrone - Corpus luteum)

b) Estrogen produced by the follicular cells help in the regeneration of endometrium of the uterus through proliferation.

progesterone, produced by the corpus luteum is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy.

30. Suggest three simple principles through which we can prevent sexually transmitted diseases.

Ans: Three simple principles to prevent sexually transmitted diseases given below:

1. Avoid sex with unknown partners/multiple partners.

2. Always use condoms during coitus.

3. In case of doubt, go to a qualified doctor for early detection and get complete treatment if diagnosed with disease.

31. What is Adaptive Radiation? Give any two examples.

Ans:

It is the evolutionary process in which different species starting from a common point in a geographical area radiate to other geographical areas.

a) Darwin's Finches

b) Marsupials of Australia

32. Name of the drugs, its source and nature is given in the table below. Find a, b and c.

Ans:

33. How did an American Company Eli Lilly use the knowledge of rDNA technology to produce human insulin?

Ans:  In 1983, Eli Lilly an American company prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

34. An example for grazing food chain is given below:

Grass → Grasshopper → Birds → Man

Graphically represent this food chain through pyramid of energy and write different trophic levels with their energy content.

Ans:

PART – D

Section - I

V. Answer any FOUR of the following questions in about 200 – 250 words each wherever applicable:

5 x 4 = 20

35. Draw a neat labelled diagram of sectional view of the mammary gland.

Ans:

36. Schematically represent the inheritance of flower colour in snapdragon and draw conclusions.

Ans:

37. Give reasons for the following:

a) A simple cut result in non-stop bleeding in haemophilia affected individuals.

b) Turner’s syndrome affected females are usually sterile.

c) In Morgan’s dihybrid cross experiments on Drosophila showed that flies having genes for yellow body and white eyes exhibited less recombination.

d) Inheritance of skin colour in the humans shows different phenotypes.

e) Accumulation of phenylalanine in the body of phenylketonuria affected individuals.

Ans:

a)  In haemophilia, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected. Due to this, in an affected individual a simple cut will result in non-stop bleeding.

b) This disorder is caused due to the absence of one of the X chromosomes, i.e., 45 with X0, Such females are sterile as ovaries are rudimentary.

c) Because they are linked genes located close together on the X chromosome, reducing the likelihood of crossover events between them.

d) The inheritance of skin color in humans shows different phenotypes because it is a polygenic trait, controlled by multiple genes (e.g., A, B, and C) that influence melanin production. Each dominant allele adds to melanin production, resulting in a wide range of phenotypes, from very light to very dark skin tones.

e) The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives.

38. Describe the steps involved in DNA fingerprinting technique. 

Ans:

• DNA is isolated and extracted from the cell or tissue by centrifugation.

• By the process of polymerase chain reaction (PCR), many copies are produced. This step is called amplification.

• DNA is cut into small fragments by treating with restriction endonucleases.

• DNA fragments are separated by agarose gel electrophoresis.

• The separated DNA fragments are visualised under ultraviolet radiation after applying suitable dye.

• The DNA is transferred from electrophoresis plate to nitrocellulose or nylon membrane sheet. This is called Southern blotting.

• VNTR probes are now added which bind to specific nucleotide sequences that are complementary to them. This is called hybridisation.

• The hybridised DNA fragments are detected by autoradiography. They are observed as dark bands on X-Ray film.

39. Name the causative agents of the following diseases:

a) Malaria b) Filariasis c) Ascariasis d) Amoebiasis e) Pneumonia

Ans:

a) Malaria - Plamodium vivax, Plasmodium falciparum, and Plasmodium Malariae

b) Filariasis - Wuchereria (W. bancrofti and W. malayi)

c) Ascariasis - Ascaris lumricoides

d) Amoebiasis - Entamoeba histolytica

e) Pneumonia -  Streptococcus pneumoniae and Haemophilus influenzae

40. a) With respect to the microbial products, its source and uses identify the a, b and c in the following table: (3M) 

b) Define the BOD and flocs.

Ans:

BOD: Biochemical oxygen demand, is the amount of oxygen that biological organisms use to break down organic matter in water.

Flocs: Masses of bacteria and fungal filaments that form a mesh-like structure.

41. Mention the population interactions exist among the following:

a) Abingdon tortoise and goats

b) Tiger and deer

c) Sea-anemone and clown fish

d) Wasp laying eggs in fig fruit

e) Cuscuta growing on hedge plant

Ans:

a) Abingdon tortoise and goats - Competition

b) Tiger and deer - Predation

c) Sea-anemone and clown fish - Commensalism

d) Wasp laying eggs in fig fruit - Mutualism

e) Cuscuta growing on hedge plant - Parasitism

Section – II

VI. Answer any ONE of the following questions in about 200 – 250 words each wherever applicable:

5x 1= 5

42. Picture of a mature angiosperm embryo sac is given below and answer the question that follows.

a) Which cells/nuclei of the embryo sac produce zygote and primary endosperm nucleus? (2M)

b) What is the ploidy of antipodal cells and primary endosperm nucleus? (2M)

c) Why the endosperm development precedes embryo development? (1M)

Ans:

a) Zygote - Egg Cell,

Primary endosperm nucleus - Polar Nuclei

b) Antipodal Cells - Haploid (n)

Primary endosperm nucleus - Triploid (3n)

c) The endosperm provides nutrients and growth regulators to the developing embryo.

43. Answer the following:

a) Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical template strand given below. (3M)

b) Write the RNA strand transcribed from the above transcription unit along with polarity. (2M)

Ans:

a)

b)

44. Study the diagram given below and answer the questions that follow:

a) What is EcoRI? (1M)

b) How is the action of exonuclease different from that of endonuclease? (2M)

c) How are ‘sticky ends’ formed on a DNA strand? Why are they so called? (2M)

Ans:

a) EcoRI is a Restriction Endonuclease extracted from E. coli.

b) Exonucleases remove the nucleotides from the ends whereas endonucleases make cuts at specific positions within the DNA.

c) Restriction enzymes cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands are called sticky ends. These are named so because they form hydrogen bonds with their complementary cut counterparts.