PART – A

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

1 x 15 = 15

1. Statement I: Apomixis is the production of seeds from unfertilized ovules.

Statement II: Embryos produced from apomictic seeds are not generally identical to the parent plant.

a) Statement I is true, statement II is false

b) Statement I is false, statement II is true

c) Statement I and statement II both are true

d) Statement I and statement II both are false

Ans: a) Statement I is true, statement II is false

2. Choose the correct option from the table given below for the formation and dissolution of the labeled part in the given diagram.

Ans: d) Formed by secondary oocyte and dissolved after fertilization.

3. Out of the options given below choose the correct stage for transfer to the fallopian tube for successful IVF results.

a) Embryo up to 8 blastomeres

b) Embryo up to 16 blastomeres

c) Embryo up to 32 blastomeres

d) Embryo up to 32 blastomeres

Ans: a) Embryo up to 8 blastomeres

4. 37.2% recombinant Drosophila progeny obtained in the T. H. Morgan’s dihybrid cross experiment with the phenotypes red eye color, normal body and white eye color, miniature body is due to;

a) Loosely linked and shorter distance between genes

b) Tightly linked and shorter distance between genes

c) Loosely linked and longer distance between genes

d) Tightly linked and longer distance between genes

Ans: c) Loosely linked and longer distance between genes

5. The number of nucleotide pairs present in the DNA of the primary oocyte of a new born in human

a) 3.3 x 109

b) 6.6 x 109

c) 13. 2 x 109

d) 3.3 x 107

Ans: b) 6.6 x 109

6. The factors that affect Hardy – Weinberg equilibrium are listed below;

i) Crossing over, Independent assortment

ii) Crossing over, Mutation,

iii) Genetic drift, Crossing over

iv) Independent assortment, Mutation

Choose the correct options:

a) i, ii and iii

b) ii, iii and iv

c) i, iii and iv

d) i, ii, iii and iv

Ans: d) i, ii, iii and iv

7. Interferons are most effective in making non-infected cells resistant against the spread of which of the following diseases in humans?

a) AIDS

b) Ascariasis

c) Ringworm

d) Amoebiasis

Ans: a) AIDS

8. The human host cells in which the gametocytes of malarial parasite develop are

a) Thrombocytes

b) Liver cells

c) Erythrocytes

d) Leucocytes

Ans: c) Erythrocytes

9. Which of the following water samples in the table given below will have a higher concentration of organic matter?

Ans: a) High level of pollution, high value of BOD

10. The steps of Recombinant DNA technology are given below:

i) Insertion of recombinant DNA into the host organism

ii) Amplification of gene of interest using PCR

iii) Cutting of DNA at specific locations

iv) Obtaining the foreign product

v) Downstream processing

vi) Isolation of DNA

Choose the correct option for the sequential steps of Recombinant DNA technology.

a) vi, ii, iii, iv, v, i

b) vi, i, iii, iv, v, ii

c) vi, ii, iii, iv, v, i

d) vi, iii ii, i, iv, v

Ans: d) vi, iii ii, i, iv, v

11. DNA in a clone of cells followed by detection using autoradiography is called

a) Template

b) Probe

c) Transcript

d) Cistron

Ans: b) Probe

12. Jeeva was growing a bacterial colony in a culture flask under ideal laboratory conditions where the resources sooner or later become limiting. Which of the following equations will represents the correct growth in this case?

a) dN/dt = rN

b) dN/dt = KN

c) dN/dt = rN (K – N/K)

d) dN/dt = rN (K +N/K)

Ans: c) dN/dt = rN (K – N/K)

13. Which of the following food chains is the major conduit for the energy flow in terrestrial and aquatic ecosystems respectively?

Ans: c) Terrestrial - Detrirus, Aquatic - Grazing

14. Which of the following is not an example of in-situ conservation?

a) National park and seed bank

b) National park and Zoological parks

c) Seed bank and sacred groove

d) Seed bank and Botanical gardens

Ans: d) Seed bank and Botanical gardens

15. Exploration of molecular, genetic and species level diversity for novel products of economic importance is

a) Biofortification

b) Bioprocessing

c) Bioprospecting

d) Biodiversity

Ans: c) Bioprospecting

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

1 x 5 = 5

(Competent cells, Bacteria, non-living molecule, vectors, Competent cells, Recombinant cells)

16. The interstitial space in seminiferous tubules consists of immunologically competent cells

17. The version of biogenesis is accepted by majority, as the first form of life arose slowly through evolutionary forces from non-living molecule

18. Filariasis pathogens are transmitted to a healthy person through vectors 

19. Swiss cheese with large holes is produced from bacteria

20. The host cells which have the ability to incorporate foreign DNA within them are called competent cells

PART - B

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

2 x 5 = 10

21. Complete the tabular column given below with respect to the male gametophyte of angiosperms.

22. Mention the two medical grounds on which the pregnancies are subjected to termination.

Ans: MTP is done in the following situations:

• Failure of contraceptive used during coitus or rapes.

• When continued pregnancy is harmful or fatal to either mother or foetus or both.

• In the case of foetal abnormalities.

23. Derive the phenotypic and genotypic ratio of a cross between AB blood group parents.

Ans: 

Both parents have the AB blood group, so their genotypes are IA IB.

The genotypic ratio is 1:2:1 (IA IB, IA IB, IA IB, IB IB)

The phenotypic ratio is 1:2:1.

• Blood Group A (genotype IA IA): 1/4

• Blood Group AB (genotype IA IB, IA IB): 2/4 or 1/2

• Blood Group B (genotype IB IB): 1/4

  
  

24. Which sequences of bases transcribed from DNA are found both in hnRNA and mRNA?

Ans: In a cell, the sequences of bases transcribed from DNA that are found both in hnRNA (heterogeneous nuclear RNA) and mRNA (messenger RNA) are exons.

• hnRNA is the primary transcript produced during transcription and contains both introns (non-coding regions) and exons (coding regions).

• During RNA splicing, introns are removed, and exons are joined together to form the final mRNA.

• Only the exons remain in both hnRNA and the processed mRNA, while the introns are excised and degraded.

25. “Potato tubers and Sweet potato tubers are the result of convergent evolution”. Justify the statement.

Ans: Convergent evolution refers to the process where unrelated species independently evolve similar traits or structures as a result of adapting to similar environments or ecological niches, despite not sharing a common ancestor with that trait.

Potato tubers (from Solanum tuberosum) and sweet potato tubers (from Ipomoea batatas) are both underground storage organs that have evolved to store nutrients, particularly starch, to help the plant survive adverse conditions and ensure energy reserves for new growth.

Although both serve a similar function — nutrient storage — they evolved from different plant structures:

The potato tuber is a modified stem, with nodes (called "eyes") that can sprout into new shoots.

The sweet potato tuber is a modified root.

26. What are biofertilizers? Mention its significance.

Ans: Biofertilisers are the microorganisms which enrich the nutrient (nitrogen, phosphorus, etc.) quality of the soil.

• Rhizobium is a symbiotic bacterium that lives in the root nodules of legumes and fixes atmospheric nitrogen into organic compounds.

• Azospirillum and Azotobacter are free-living bacteria which absorb free nitrogen from soil, air and convert it into salts of nitrogen like amino acids and enrich soil nutrients.

• Cyanobacteria fix atmospheric nitrogen and increase the organic matter of the soil through their photosynthetic activity, e.g., Nostoc, Anabaena, Oscillatoria, etc.

27. Name any four recent extinct organisms as per IUCN Red list. 

Ans: The dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three subspecies (Bali, Javan, Caspian) of tiger.

PART - C

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

3 x 5 = 15

28. Draw a labeled diagram of the fertilised female gametophyte and mention the ploidy of any one of the products of double fertilization.

Ans:

Endosperm: The endosperm is typically triploid (3n)

29. Parturition is induced by complex neuroendocrine mechanism. Comment. 

Ans: The act of expelling the full term foetus from the mother's uterus at the end of gestation period is called parturition.

Parturition is induced by a complex neuroendocrine mechanism.

The signal for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex.

This triggers the release of oxytocin from the maternal pituitary. Oxytocin induces stronger uterine muscle contractions which lead to expulsion of the baby from the uterus through the birth canal.

30. The popular and effective contraceptives include IUDs. Mention the types of IUDs with an example of each.

Ans: There are three types of IUDs available:

a. Non-medicated IUDs: These increase phagocytosis of sperms within the uterus, e.g., Lippes loop.

b. Copper releasing IUDs: Along with phagocytosis of sperms, the Copper (Cu) ions released suppress sperm motility and fertilising capacity of sperms, e.g., CuT, Cu7, Multiload 375.

c. Hormone releasing IUDs: These make the uterus unsuitable for implantation and the cervix hostile to sperms, e.g., Progestasert, LNG-20 (Levonorgestraol – is a hormonal medication is used in number of birth control methods).

31. Write the salient feature of the following human ancestors;

i) Dryopithecus

ii) Ramapithecus

iii) Australopithecus

iv) Homo habilis

v) Neanderthal man

vi) Homo erectus

Ans:

i) Dryopithecus: Was more ape-like creture. They were hairy and walked like gorillas and chimpanzees.

ii) Ramapithecus: Man-like primates, probably not taller than 4 feet but walked up right.

iii) Australopithecus: They hunted with stone weapons but essentially ate fruit

iv) Homo habilis: This creature was called the first human-like being the hominid, The brain capacities were between 650-800cc, They probably did not eat meat

v) Neanderthal man: With a brain size of 1400cc, They used hides to protect their body and buried their dead.

vi) Homo erectus: The brain capacity around 900cc, probably ate meat.

32. Describe any three properties of Cancerous cells.

Ans:

1. The cells divide repeatedly with uncontrolled cell division.

2. The cancer cells do not require extracellular growth factors.

3. Cancer cells have lost the property of contact inhibition.

4. They invade from one part to the other parts throgh body fluids (metastasis).

33. Complete the below given tabular column with appropriate answers. 

Ans:

34. Represent diagrammatically the pyramid of number in a Terrestrial ecosystem.

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. Flowering plants have developed many devices to discourage self-pollination and encourage crosspollination. Comment.

Ans: Self-pollination can be prevented by exhibiting:

i. Unisexuality: Male and female flowers are present on different plants.

ii. Dichogamy: The condition in which the stamens and stigma of a bisexual flower mature at different times.

iii. Protandry: This is the condition where anthers mature earlier than the stigma and release pollens.

iv. Protogyny: This is the condition where the stigma matures earlier than the anther.

v. Self-sterility or self-incompatibility: It is a genetic mechanism that prevents selfpollination.

vi. Chasmogamous flowers: These are open flowers with exposed stamens and stigma which facilitate cross-pollination.

36. Draw a labeled diagrammatic sectional view of the human female reproductive system.

Ans:

37. Few autosome linked recessive gene blood diseases occur in human population. Among them some are related to qualitative and quantitative problem of synthesizing blood proteins. Explain.

Ans: Autosomal recessive blood diseases are inherited conditions that occur when a person inherits two defective copies of a gene, one from each parent, located on non-sex chromosomes (autosomes).

• Sickle-cell anaemia is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous).

• The disease is controlled by a single pair of allele, HbA and HbS.

• Out of the three possible genotypes only homozygous individuals for HbS (HbSHbS) show the diseased phenotype.

• Heterozygous (HbAHbS) individuals appear apparently unaffected but they are carrier of the disease as there is 50 per cent probability of transmission of the mutant gene to the progeny, thus exhibiting sickle-cell trait.

• The defect is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule.

• The substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG.

38. DNA replication is fast, accurate, energetically expensive, substrate and enzyme dependent, initiated from specific site and cannot uncoil on its entire length. Explain the process of DNA replication considering all these features. 

Ans: DNA replication is a highly coordinated biological process that ensures the accurate copying of the genetic material before cell division.

• In living cells, replication requires enzymes, primarily DNA-dependent DNA polymerase, which uses a DNA template to catalyze the polymerization of deoxynucleotides. These enzymes are highly efficient, rapidly catalyzing the addition of numerous nucleotides in a short time.

• Not only do these polymerases have to be fast, but they also have to catalyse the reaction with high degree of accuracy.

• Energetically replication is a very expensive process. Deoxyribonucleoside triphosphates serve dual purposes. In addition to acting as substrates, they provide energy for polymerisation reaction (the two terminal phosphates in a deoxynucleoside triphosphates are high-energy phosphates, same as in case of ATP).

• Several enzymes are involved in different steps of DNA replication: Helicase, DNA polymerase, Primase, Ligase and Topoisomerases.

• DNA replication begins at specific sequences known as origins of replication.

• Due to the extremely long length of DNA molecules (e.g., human DNA has around 3 billion base pairs), it is not feasible or efficient to uncoil the entire DNA strand at once.

39. Some drug bottles had their name labels missing in a drug store of a hospital. The staff needs to identify the drugs with their actions still written on them. Analyse their actions listed below and identify the name of each drug and also the source of each one of them.

40. Transgenic animals provide innumerable benefits to human beings. Justify the statement with common reasons. 

Ans:

• Transgenic animals are useful to study gene regulation, their effect on the normal functions of the body and its development. For example, study of complex growth factors like insulin-like growth factor.

• Transgenic models have been developed for many human diseases like cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease.

• Useful biological products can be produced by introducing, into transgenic animals, the portion of DNA (or genes) which codes for a particular product. For example,  human protein (α-1-antitrypsin) is used to treat emphysema. In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 g/L).

• Transgenic mice are developed to test safety of vaccines, before being used on humans. For example, transgenic animals are being used to test the safety of the polio vaccine.

• Transgenic animals are made to carry genes, which make them more sensitive to the toxic substances than non-transgenic animals. On exposing to the toxic substances, their effects are studied in less time.

41. Explain the fascinating forms of interactions in;

a) Brood parasitism

b) Sexual deceit

Ans:

a) Brood parasitism in birds is a fascinating example of parasitism in which the parasitic bird lays its eggs in the nest of its host and lets the host incubate them. During the course of evolution, the eggs of the parasitic bird have evolved to resemble the host’s egg in size and colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.

b) The Mediterranean orchid Ophrys employs ‘sexual deceit’ to get pollination done by a species of bee. One petal of its flower bears an uncanny resemblance to the female of the bee in size, colour and markings. The male bee is attracted to what it perceives as a female, ‘pseudocopulates’ with the flower, and during that process is dusted with pollen from the flower. When this same bee ‘pseudocopulates’ with another flower, it transfers pollen to it and thus, pollinates the flower.

Section – II

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

5x 1= 5

42. Results of a Mendelian dihybrid cross are represented in the form of Punnett square.

Answer the following questions with respect to the results of a dihybrid cross.

a) Number of parental types progeny

b) Number of recombinant progeny

c) Number of homozygous recessive progeny

d) Number of homozygous dominant progeny

e) Number of homozygous progeny for both the traits

f) Number of heterozygous progeny for both the traits

g) Number of pure line progeny

h) Number of homozygous progeny for single trait

i) Number of heterozygous progeny for single trait

j) Number of recessive progeny for single trait

Ans:

43. Given below are sequences of nucleotides in a particular mRNA and amino acids coded by it;

5’- AUG UUU UUC GAG UUA GUG UAA-3’

met phe phe glu leu val

Write the properties of genetic code that can be correlated from the above given data

Ans:

• The codons are triplet. Out of 64 codons, 61 code for 20 amino acids and 3 codons (UAA, UGA, UAG) do not code for any amino acid, hence function as stop or terminating codons.

• One codon codes for only one particular amino acid, hence the code is unambiguous and specific.

• The codon is read on mRNA in a continuous fashion, i.e., without punctuations and thus the code is comma less.

• Genetic code is nearly universal,i.e., a particular codon codes for the same amino acid in all organisms except in mitochondria and few protozoa.

• AUG is a dual function codon, it codes for methionine (met) and it is also acts as initiator codon.

44. Given below are the diagrams of plasmids A and B, observe meticulously and answer the questions that follows;

a) Which plasmid is/are you select for cloning and why? (1M)

b) What is insertional inactivation? (1M)

c) Will the number of culture plating you should make is same or different to select recombinant if insertional inactivation is possible.

Comment

Ans:

a) Plasmid A can be selected for cloning. The vector requires a selectable marker, which helps in identifying and eliminating nontransformants and selectively permitting the growth of the transformants.

b) A recombinant DNA is inserted within the coding sequence of an enzyme, â-galactosidase. This results into inactivation of the enzyme, which is referred to as insertional inactivation.

c) We can see different colonies in culture plating:

• When recombinant DNA is inserted into the plasmid's coding sequence for β-galactosidase, the enzyme becomes inactivated. As a result, bacteria containing the recombinant plasmid produce white colonies.

• Bacteria with non-recombinant plasmids (without the insert) will retain an active β-galactosidase enzyme, leading to the formation of blue colonies.