CSIR NET LIFE SCIENCE PART C DEC 2019 PYQ

1

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A form and Z form of double stranded DNA differ in the handedness of their helices, nucleotide sequences, and configuration of base to sugar. Based on these properties, which one of the following statements defines a correct combination for A and Z forms of DNA?

2

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below is the [P] vs time plot of an enzymatic reaction carried out by the enzyme ‘X’Which one of the following statements is the correct interpretation of the data?

3

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are some physicochemical properties (column X) and their manifestations (column Y).
Which one of the following is the most appropriate match?

4

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The following observations are made on a 30-residue polypeptide
i. Unordered structure is observed in water, but a helical conformation is observed in a medium of low dielectric constant
ii. The peptide is resistant to degradation by proteases.
iii. Red blood cells are lysed by the peptide.
iv. β-mercaptoethanol has no effect on peptide structure.
Which of the following statements can be correctly attributed to the above observations?

5

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The following statements are made.i. B form of DNA has ~10 base pairs/turn and A form of DNA has ~2.3 A helix rise per base pairii. Both the A and B form of DNA have wider major groove and narrow minor grooveiii. The crystalline nature of cellulose is brought about by α (1→4) linkage between the glucose subunits.iv. The double bonds in natural lipids are always cis, which provides fluidity to the plasma membrane.Which of the following combinations represent the correct statements?

6

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Analysis of a homotetrameric protein and a double stranded DNA (that had been incubated in standard buffer) on native gels revealed that they migrated true to their physical states (tetrameric nature of the protein and double stranded nature of the DNA). Following hypotheses were made for the effect of adding high salt to the incubation mix and subsequent analysis on native gels.i. The protein would migrate as a homotetramer and DNA in double stranded form.ii. The protein would migrate as a monomer but DNA in double stranded form.iii. The protein would migrate as a homotetramer but the DNA in single stranded form.iv. The protein would migrate as a monomer and the DNA in single stranded form.Which of the following combination of hypotheses is most likely?

7

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The nucleosome is the fundamental subunit of chromatin in eukaryotes. Following statements are made about nucleosome:
i. Generally, a typical nucleosome contains ~200bp of DNA and two copies of each histone (H2A, H2B, H3 AND H4)
ii. 146 bp length of DNA per nucleosome core particle is strictly maintained across the organisms
iii. The histone octamers are not conserved during/after replication, however, H32-H42 tetramers are.
iv. Variants have been identified for all core histones except histone H3
v. While wrapping around the core histones, the structure of DNA is altered at the middle of the nucleosome core particle and exhibits an increased number of base pairs per turn
Which one of the following combination of statements is most appropriate?

8

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

During cell cycle, entry in the S-phase is tightly regulated. This is possible because:
i. APC/C promotes ubiquitination of S-phase cyclins and mitotic cyclins, marking them for proteolyses at the mitotic exit.
ii. Cyclin B1 helps in the activation of S-phase CDKs only in late G1
iii. As mitotic CDK activity declines in late mitosis, cdc14 phosphatase activates APC/C by dephosphorylating Cdh1, thus promoting formation of APC/CCdh1.
iv. Securin keeps S-phase cyclins in inactive state till late G1
Which one of the options represents all correct statements?

9

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Thousands of proteins that are synthesized in the cytoplasm are imported into the nucleus through the nuclear pore complex (NPC) every minute. These proteins contain Nuclear Localization Signal (NLS) that direct their selective transport into the nucleus. This nuclear import requires:i. A small monomeric G-protein Ran.ii. A nuclear transport receptor that interacts with the NLS on a cargo protein.iii. A GTPase activating protein (GAP) bound to the chromatin tethered to the nuclear membrane.iv. A Guanine Exchange Factor (GEF) bound to the chromatin inside the nucleus.Which one of the following options represents all correct statements?

10

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Listeria is a food-borne pathogen that causes mild gastro-intestinal symptoms. To move from one host cell to another, it polymerizes actin into a comet tail-like structure. Listeria can assemble host-cell actin at its rear end because:
i. Listeria has on its surface a protein called Act A
ii. Listeria can activate Arp 2/3 complex
iii. Listeria has on its surface g-tubulin
iv. Listeria has on its surface myosin II motor
Which one of the following options represents all correct statements?

11

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The membrane phospholipid structures in bacteria and archaea differ. Which one of the following correctly states the differences between the two?

12

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Deletion analysis of a promoter region of a gene was carried out to identify the regulatory elements in it. In the figure below, the filled boxes denote the areas of deletion and the observed activities (in arbitrary units) of the promoter are as shown.
Based on the observations, following statements were made:
i. The region between –100 and -50 houses a positive regulatory element.
ii. The region between -200 and -250 houses a negative regulatory element.
iii. The region between -150 and -200 houses a positive regulatory element.
Which one of the following options represents the correct interpretation of the data?

13

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Following statements were made with respect to transcription in eukaryotes:
i. RNA polymerase III synthesizes mRNAs in the nucleoplasm
ii. The target promoter for RNA polymerase III is usually represented by a bipartite sequence downstream of the transcription start site.
iii. The assembly factor TFIIIA and TFIIIC assist the building of the positioning factor TFIIIB at the precise location.
iv. TFIIIB is the last factor that joins the initiation complex.
v. Phosphorylated Ser residues in the C-terminal domain (CTD) of RNA polymerase II serve as binding sites for mRNA processing enzymes.
Which one of the following options represents the correct combination of the statements?

14

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The figure below shows the structure of a replication fork.Based on this information, following statements are made:a. (i) represents the leading strand while (ii), (iii) and (iv) represent the Okazaki fragments.b. Among the Okazaki fragments, synthesis of (iv) occurs prior to the synthesis of (iii) and (ii).c. Among the Okazaki fragments, synthesis of (ii) occurs prior to the synthesis of (iii) and (iv)Which one of the following options represents the correct statements(s)?

15

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Many organisms encode only 18 aminoacyl-tRNA synthetases (aaRS). These organisms lack aaRS that use Asn or Gln (as one of the substrates) for direct aminoacylation of the tRNAAsn and tRNAGln, respectively. Which one of the following statements represents the correct option?

16

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Ribosomes prepared from a bacterium were fractionated by sucrose density gradient centrifugation (panel i) to separate the 30S, 50S and 70S populations. When the ribosome preparation was incubated individually with either elongation factor-G (EF-G), or a newly identified protein X, or GTP, the profile remained unchanged. Likewise, no changes were seen in the profile when the ribosomal preparation was incubated with EF-G + GTP or protein X + GTP. However, when the ribosomal preparation was incubated with protein X, EF-G and GTP together, it resulted in a change of profile which showed a decrease of the 70S peak area and increase in the peak areas for 30S and 50S (panel ii).Choose the option that defines a correct conclusion from the observations.

17

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Following statements were made about the post-transcriptional processing of RNA in eukaryotes.
i. Soon after transcription initiation, RNA polymerase II pauses ~30 nucleotides downstream from the site of initiation until the Cap structure is added to the 5’ end of the nascent pre-mRNA.
ii. The 5’ splice sites are functionally divergent whereas the 3’ sites are functionally equivalent.
iii. In addition to helping in recognition of the splice sites, the exon definition also functions as a splicing regulator by allowing pairing and linking of adjacent 5’ and 3’ splice sites.
iv. The intron definition mechanism applies only to the larger introns (above 500 nucleotides length) and assists in achieving alternate splicing.
v. The splicing reactions carried out in vitro have revealed that the first and second transesterification reactions are reversible.
Which one of the following combination of statements is correct?

18

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In the diagram below, the dotted line marks the point of initiation of bidirectional replication.i. On the right side of the dotted line, leading strand synthesis occurs using the upper strand as the template.ii. On the right side of the dotted line, leading strand synthesis occurs using the lower strand as the template.iii. A ligase deficient (lig-) mutant would affect replication of the upper strand on the left side of the dotted lineiv. A ligase deficient (lig-) mutant would affect replication of the lower strand on the left side of the dotted line.Which one of the following options represents the combinations of the correct statements?

19

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Bacterial infections are generally divided into two broad classes: intracellular and extracellular bacterial infections. Given below are some of the properties which are applicable for bacterial infections.i. Humoral immune response is the main protective response against extracellular bacteria.ii. Innate immunity is not effective against intracellular bacterial pathogens.iii. Bacterial endotoxins do not induce an innate immune response.iv. Intracellular bacterial infections generally induce a cell- mediated immune response resulting in secretion of cytokines which activate macrophages.Which one of the following combination of statements is correct?

20

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In the table below Column A lists ligands and Column B lists classes of receptors:Which one is the correct match?

21

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Cells are physically linked to one another and to extracellular matrix through their cytoskeleton and this imparts strength and rigidity of tissues and organs. Most of the animal cells have three types of cytoskeletal filaments, which are listed in Column A. The possible functions are listed in Column B.Which one is the correct match?

22

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Acetylcholine is a potent neurotransmitter, which is released from the neurons. After release they diffuse across the synaptic cleft and combine with nicotinic acetylcholine receptor molecules in the membrane of the postsynaptic cell. The interaction of acetylcholine with the nicotinic acetylcholine receptor produces large transient increase in the permeability of the membrane to specialized ions resulting in signal transduction for nerve impulse. Acetylcholine receptor is a

23

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Strain A mice were crossed with strain B mice and first generation F1 mice were obtained, i.e. (A x B)F1. A scientist then implanted thymectomized and irradiated (A x B)F1 mice with a B-type thymus and then reconstituted the animal’s immune system with an intravenous infusion of (A x B)F1 bone marrow cells. The chimeric mice were infected with lymphocytic choriomeningitis virus (LCMV) and the spleen T cells were then tested for their ability to kill LCMV – infected target cells from the strain A or strain B mice.Which one of the following is the correct outcome of the experiment?

24

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The anterior-posterior compartment of each segment of Drosophila is defined by wingless and engrailed genes. The following statements are given towards explaining their regulation:i. Wingless is a secretory factorii. Engrailed is a secretory factor and forms a long-range concentration gradientiii. Engrailed regulates Wingless through Hedgehog which forms a short-range concentration gradientiv. β-catenin homologue is the signaling molecule upstream of Engrailed, which gets cleaved by GSK3 homologuev. Cubitus interruptus is an intracellular signaling molecule in the Engrailed expressing cells.Which one of the following options has all the correct statements towards the regulation of anterior-posterior compartment of segments?

25

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Following statements are being made regarding specification/ determination during animal development:i. During the course of commitment, the cell may not appear different from its nearest or most distant neighbors in the embryo and show no visible signs of differentiation; but its developmental fate is restricted.ii. At the stage of specification, cell commitment is not labile.iii. A cell or tissue is determined when it is capable of differentiating autonomously even when placed into another region of the embryo, or a cluster of differently specified cells in a petridish.iii. Cytoskeletal arrangements maintain positioning of nuclei in the syncytium, which enables specification of these nuclei by opposing morphogen gradients namely Bicoid and Caudal in Drosophila.iv. Capacity for “mosaic” development allows cells to acquire different functions as a result of interactions with neighboring cells.Which of the above statements are correct?

26

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A “morphogen” can determine the fate of a cell by its concentration. Given below are some statements on the experiment performed to study the gradient-dependent effect of the morphogen, activin on cell fate by placing activin (4 nm) – secreting beads on unspecified cells from an early Xenopus embryo:
i. Beads without activin did not elicit expression of either Xbra or goosecoid genes.
ii. Cells nearest to the beads getting highest concentration of activin induced goosecoid gene whose product is a transcription factor, specifies the frog’s dorsal-most structures.
iii. Cells nearest to the beads getting highest concentration of activin induced Xbra gene whose product is a transcription factor, specifies the frog’s dorsal-most structures.
iv. Cells farthest from the beads getting negligible activin activate Xbra gene and become blood vessels and heart.
v. Cells farthest from the beads getting negligible activin, activated neither Xbra nor goosecoid and the ‘default’ gene expression instructed the cells to become blood vessels and heart.
Which of the above observations and conclusions drawn are correct?

27

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Following statements were made about the events occurring during chick development.i. The fertilized chick egg undergoes discoidal meroblastic cleavage, however the cleavage does not extend into the yolky cytoplasm.ii. Development of primary hypoblast is mediated by localized migration of a group of highly specified and connected cluster of 30-40 cells.iii. By the stage XIII of chick embryogenesis and little prior to primitive streak formation, the formation of the hypoblast is just complete.iv. Hensen’s node of the chick embryo signifies a region at the anterior end of the primitive streak with regional thickening of cells.v. Inhibition of Wnt planar cell polarity pathway in the epiblast causes the mesoderm and endoderm to form centrally instead of peripherally.Which one of the following combinations represents all correct statements?

28

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The following diagram represents a longitudinal section through an Arabidopsis shoot apical meristem (SAM) and leaf primordium at its flank. The dorsal (D) and verntral (V) domains are marked. The D and V genes are expressed in the dorsal and ventral domains, respectively.
Consider the following statements describing the phenotypes of leaf polarity.
i. Loss of D function makes the leaf ventralized whereas its overexpression dorsalizes the leaf.
ii. Loss of V function makes the leaf dorsalized whereas its overexpression ventralizes the leaf.
iii. Loss of microRNA miR166 dorsalizes the leaf whereas its overexpression ventralizes the leaf.
iv. miR166 functions by inhibiting its target mRNA
Which one of the following functional models best describes the above results?

29

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

During fertilization in mammals proteins Izumo and Juno are required for recognition of sperm and egg. Izumo and Juno are found specifically in sperm and egg, respectively. Which one of the following in vivo experiments will demonstrate that Izumo and Juno interact with each other?

30

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Match the above columns involving plant hormones and their signaling pathways:

31

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which one of the following graphs best represents the net CO2 fixation of typical C3 and C4 plants under increasing CO2 concentration and saturating light?

32

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Certain plant species produce cyanogenic glycosides to protect them from pathogens. A researcher has identified a variant of such a plant that has higher level of cyanogenic glycoside yet it is highly susceptible to a specific fungal pathogen. To interpret this counter-intuitive observation, the researcher hypothesizes that the fungal pathogen has higher level ofi. β-glucosidase activityii. formamide hydorlyase activityiii. cytochrome P-450 enzymeiv. cyanide-resistant, alternative oxidase activityWhich one of the following combinations of the above hypotheses is correct?

33

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The following statements were made with the assumption that the concentration of 3-phosphoglycerate is high inside chloroplasts of an actively photosynthesizing leaf.
i. There will be high concentration of triose phosphate in the chloroplast.
ii. The activity of ADP-glucose pyro phosphorylase will be inhibited.
iii. The carbon flow will be diverted from sucrose to starch.
iv. Starch synthesis will be inhibited, and carbon flow will be more towards sucrose synthesis.
Which one of the following combinations of above statements is correct?

34

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A disease-resistant plant was crossed with a susceptible plant and the resultant F1 plants were disease resistant. The F1 plant was selfed and the F2 individuals were analyzed for qualitative and quantitative disease resistance. The following statements were hypothesized.i. Qualitative resistance follows Mendelian ratio.ii. In the F2 individuals demonstrating qualitative resistance, “resistance” is dominantiii. Quantitative resistance is always monogeniciv. Qualitative resistance can be polygenicWhich one of the following combination of statements is correct?

35

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Consider the following facts:
i. Chlorophyll absorbs more in the red region of the visible spectrum than in far-red.
ii. The phytochrome photoreceptor (P) of plants occurs in two inter convertible forms, Pr and Pfr where red light converts Pr to Pfr and far-red light converts Pfr to Pr.
iii. Growing a sun plant under the canopy shed causes increased stem elongation
Which one of the following combination of statements is correct for the plants growing under the canopy as compared to those growing above the canopy?

36

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Thyroid hormone (T3) increases the heart rate and the force of contraction of cardiac muscles. The mechanisms of these effects of T3 have been explained by a researcher in the following statements:i. T3 inhibits the expression of gene for α-myosin heavy chain and enhances the expression of gene for β-myosin heavy chainii. The expression of gene for Na+-Ca++ antiporter is enhanced by T3iii. The sarcoplasmic reticulum Ca++ ATPase is increased by T3iv. T3 increases ryanodine Ca++ channels in the sarcoplasmic reticulumv. The number of β-adrenergic receptors in heart muscles is inhibited by T3Which one of the following combinations contains both correct explanations?

37

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In the nervous system, the action potential is generated at the axon hillock in physiological conditions and it is conducted to the terminal end of axon. The location specific origin of action potential and its direction-specific conduction are explained by a researcher in the following proposed statements:i. The membrane of axon hillock has highest threshold for the generation of action potentialii. The membrane of axon hillock contains large numbers of voltage-gated Na+ channels and that makes it more excitableiii. The propagating action potential in the middle of the axon cannot generate another action potential in the direction of cell body since a large fraction of voltage-gated Na+ channels in the preceding portion is voltage inactivatediv. As the number of voltage-gated Na+ channels is less in the preceding portion of axonal membrane, the propagating action potential in the middle of the axon cannot generate another action potential in the direction of cell body.Which one of the following combinations represents both correct explanations?

38

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Aldosterone increases the reabsorption of Na+ from the tubular fluid in the thick ascending limb of loop of Henle and in the distal tubule. These effects are explained in the following proposed statements:i. Aldosterone increases the number of Na+-Cl- symporter in the apical membrane of principal cells in the early portion of distal tubule.ii. The number of Na+ channels (ENaC) is increased in the apical membrane of principal cells in the late portion of distal tubule by aldosteroneiii. The synthesis of Na+, K+-ATPase in the basolateral portion of principal cells in distal tubule is decreased by the action of aldosteroneiv. Aldosterone increases the reabsorption of Na+ across the apical cell membrane in the thick ascending limb of loop of Henle by decreasing Na+, K+-ATPase in itWhich one of the following combinations represents both correct statements?

39

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Hormones act by producing/activating a variety of effectors intracellularly. Below are given a variety of effectors in column ‘X’ and hormones in column ‘Y’Which one of the following combinations of effector and the specific hormone is correct?

40

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Drawn below is an intestinal epithelial cell (IEC) performing the absorption of digested monosaccharides from the dietary carbohydrates ingested.Which one of the following combinations of the transporter (A, B and C in the figure above) and the transported monosaccharide is correct?

41

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Individuals in a population are divided into various blood groups (in column ‘X’) based on the set of enzymes they have (in column ‘Y’):Which one of the following combinations is NOT correct for the blood group type and the set of enzymes a person has?

42

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In an organism, a+ allele governs gray body colour, while its mutant allele a gives yellow body color. Further, presence of b+ allele gives long and thin hairs while b allele gives rise to short and thick hairs. The alleles a+ and b+ are dominant over a and b, respectively. An individual with the genotypehas a patch of yellow cells with short and thick hairs. Which one of the following events is most likely to lead to the above?

43

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The individuals considered in this question are having two haploid sets of autosomes and no Y-chromosome. The X:A ratio of the individuals, the type of organisms chosen, their primary sex and number of Barr bodies expected in their cells are shown in the table below:Select the option below with all correct matches:

44

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In the following pedigree three STR loci A, B and C are linked on the long arm of the X-chromosome in the order centromere-A-B-C-telomere. Further in the table, the STR alleles present in each individual is indicated.Based on the above, X-chromosome(s) in which of the following individuals are recombinant?[Hint: X-chromosome in males will help identify the phase of the alleles]

45

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A mutant mating type mt strain of Chlamydomonas that was resistant to the antibiotic kanamycin (kanr) and herbicide PPT (pptr) was crossed to a wild type mating mt+ kans ppts strain that was sensitive to kanamycin and PPT. Twenty tetrads of the progeny were analyzed for mating type and resistance/ sensitivity to kanamycin and PPT. The following observations were made:The following statements were made to explain the observations:i. mt and ppt loci are on two different chromosomesii. Inheritance of mating type and ppt-resistance/sensitivity are demonstrating cytoplasmic inheritanceiii. Inheritance of kanamycin-resistance/sensitivity is demonstrating nuclear inheritanceiv. Nuclear inheritance is being demonstrated by mating type and ppt-resistance/ sensitivity analysisWhich one of the combinations of above statements is correct?

46

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A pedigree shown below depicts that the individual I-1 is heterozygous for a dominant disease allele D and for molecular markers M1/M2. The paternal molecular markers present in the progeny individuals are indicated in the pedigree.The following statements may be drawn from the above pedigree:i. The two loci D/d and M1/M2 appears to be linkedii. The recombination frequency between the two loci is 20%.iii. If LOD score comes out to be 3, then it ensures that the two loci are independently assortingiv. A LOD score <1 would have ensured that the two Loci are linkedWhich combination of the above statements can correctly interpret the depicted pedigree?

47

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

An individual is having a paracentric inversion (denoted by the region f-e-d, marked by arrows) in homozygous condition.The meiotic consequences of inversion can be:i. generation of an acentric and a dicentric chromosomeii. the recombinants will have long deletion or duplication and may be lethaliii. the inversion will suppress crossing overiv. all gametes will have complete genome and will survive normallyWhich of the above statement or their combinations will explain the meiotic consequence of the given inversion logically?

48

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Following statements are made about double-strand break repair (DSBR) model of homologous recombination:i. Process of DSBR recombination is triggered by introducing a double-strand break in a DNA duplexii. In a process known as 3’ –end resection, the exonucleases along with a DNA helicase degrade one strand on either side of the break and generates 3’-single stranded terminiiii. One strand of the donor duplex is displaced due to formation of heteroduplex DNA and generates a displacement loop (D-Loop)iv. Branch migration allows the point of crossover to move in 5’ → 3’ direction of recipient strandv. Completion of DSBR recombination may generate either crossover recombinant or non-recombinant productWhich one of the following combination of statements is correct?

49

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which of the following set of conditions will qualify a species to be considered as endangered (EN) as per IUCN criteria?

50

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are certain adaptation which are seen in various groups of animals:a. Oviparyb. Streamlined bodyc. Pouch for carrying eggsd. Porous eggshelle. Breastbone as large keelf. Webbed feetg. Laterally compressed coccygeal boneh. Unidirectional pulmonary system to provide large quantities of oxygeni. Barbules or hooklets on the vanes of each featherWhich combination of the above adaptations facilitate bird flight?

51

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Match the following taxa with the genus of the microorganism:

52

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Match the following plant diseases with the name of pathogen associated with the disease:

53

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which one of the following phylogenies best represents the evolutionary relationship among whales, dolphins, seals, deer and dogs?

54

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The table below shows photosynthetic type, temperature and sunlight intensity levels.Which of the following correctly matches the plant photosynthetic type with the temperature and sunlight conditions in which photosynthetic rate per unit leaf area is maximum for that plant?

55

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which of the following represents exponential growth in populations?

56

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

In the graph below, large boxes (denoted by P, Q, R, S) represent a region, whereas smaller boxes represent habitats. Labels S1, S2,…… above each small box represent species present in the given habitat denoted by that box.P. Q. R. S. Given the above graphs, choose the option which correctly depicts the regions which show maximum α and maximum β diversity, respectively.

57

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which among the above sets of conditions are best suited for mimicry to be successful?

58

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Which of the following is NOT a mechanism for species coexistence?

59

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A small number (approximately 10) of mice are introduced into an uninhabited island. Their population grows exponentially initially and after 3 years, reaches a population size of 520 after which the population becomes stable. At what point would you expect their population to attain their highest growth rate?

60

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Area of patch 1 is 2000 m2 with a resource density of 5 units/ m2. Area of patch 2 is 3000 m2 with a resource density of 10 units/ m2. As per the theory of ideal-free distribution, organisms distribute themselves such that the expected ratio of abundance of organisms in the two patches (path 1 : patch 2) is:

61

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Match the geological time period with the extinction or diversification events associated with them:

62

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Female fiddler crabs prefer male fiddler crabs with larger claws over males with smaller claws. If the selection pressure exerted is strong resulting in a skewed distribution of claw size, which of the following statements is true about the population’s mean, median and mode?

63

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The phylogeny below shows evolutionary relationships between 9 extant bird species and whether they display red or blue plumage.Based on the above phylogeny and the distribution of red and blue character states among the extant species, and using the principle of parsimony, which of the following is the correct inference about plumage colour of the ancestor at the root P?

64

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

The Top panel (graphs a-c) represents trends of number of sperms produced per mating season with respect to number of mates, while the Bottom panel (graphs i-iv) represents trends of time invested in paternal care with respect to number of mates in birds.Select the correct trend from each panel.

65

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are various types of molecular markers in Column A and properties of these markers in Column B :Which one of the options given below correctly matches the molecular markers with their properties?

66

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Several plants produce metabolites with important medicinal properties and have been extensively used in traditional medicine across the world. Many of these compounds can now be purified or synthesized and are used in modern medicine. Given below is a list of metabolites, their plant source and medicinal use:
Which one of the following options is the most appropriate match of the compound with its plant source and use?

67

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are schematic representations of the T-DNA regions of four constructs that are to be used for Agrobacterium – mediated transformation to silence an endogenous plant gene represented as ‘XYFP’ that is expressed constitutively in the plant.A) B) C) D) M: Selectable marker gene expression cassetteLB: Left BorderRB: Right BorderWhich of the four constructs depicted above could be used to silence the target gene ‘XYFP’?

68

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are a few statements on use of plant breeding to develop improved varieties of a crop plant:
i. Genotypic/ phenotypic variation in the desired trait should be available in the germplasm resources of the crop plant.
ii. Availability of molecular markers linked to the trait of interest would decelerate the process of trait introgression into desired varieties.
iii. Breeding procedures to improve plant varieties are generally more successful among sexually compatible species as compared to sexually incompatible species.
iv. Co-dominant molecular markers cannot be used for selection of plants with the desired trait.
Which of the above statement(s) is/are INCORRECT?

69

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

A mixed cell population was stained with two antibodies, one specific for cell surface antigen A and the other specific for cell surface antigen B. Anti-A antibody was labeled with fluorescein and anti-B antibody was labeled with rhodamine. The cell population was then analyzed for the presence of antigens by flow cytometry. Which one of the following is the correct outcome for this cell population?

70

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

The following statements are made regarding developing a transgenic mouse:a. The transgenic mouse thus born will be a homozygous transgenic animal and can be maintained by crossing with another transgenic animal.b. The fertilized transgenic eggs are allowed to develop in vitro.c. The desired gene is preferably microinjected in male pronucleus after sperm entry in oocyte.d. For best efficiency the desired gene is always microinjected in the male gametes and then they are allowed to fertilize the female gametes.e. Blastocyst stage embryos are transferred to the uterus of hormonally prepared mother.f. The fertilized eggs are collected from specific strain of mouse.g. The female mouse of specific strain is super ovulated, oocytes are collected and allowed to fertilize in vitro.Choose the combination of statements arranged in the correct sequence for developing transgenic mouse.

71

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

The ECG recorded by different leads is analyzed on the basis of variation of electrical potential at various loci on the surface of the body, and the time scale relation of different waves. After analyzing the ECG, following particulars of heart are proposed to be obtained:i. Stoke volume and cardiac outputii. Volume and pressure changes during cardiac cycleiii. Anatomical orientation of heartiv. Various disturbances in the rhythm and conduction of cardiac excitationv. The extent, location and progress of ischemic damage to myocardiumWhich one of the following combinations represents both INCORRECT particulars of heart?

72

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

Given below are two sets of terms related to various methods used in biological science.
Which one of the following options correctly matches terms of Column A and Column B?

73

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

In an experiment a 1 kb fragment with a single BamHI site (as shown below in figure ‘A’) is to be cloned in the SmaI (CCC ↓ GGG) site of a cloning vector of 3kb length (figure ‘B’). None of the other enzymes of the multiple cloning site are present in the fragment to be cloned.Based on the information given above, a series of digestions were set up for the potential clones and their fragment profiles are given below:i. BamHI : 200bp + 3.8 kbii. BamHI : 800bp + 3.2 kbiii. HindIII+EcoRI : ~1kb + ~3kbiv. XhoI+BamHI : ~200bp + ~800bp + ~3kbWhich one of the above digestion profiles confirms successful cloning of the fragment in the vector in an orientation wherein the 5’ end of the cloned fragment is towards ‘P’?

74

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

To investigate the dynamic nature of two unrelated centrosome-localized GFP-tagged proteins [GFP-A; GFP-B], a team of scientists conducted fluorescence recovery after photo bleaching (FRAP) experiment. The FRAP profile of these two proteins is given below:The following statements for the FRAP analysis were madei. GFP-B shows faster exchange rate than GFP-Aii. GFP-A shows faster exchange rate than GFP-Biii. GFP-A has more immobile fraction than GFP-Biv. GFP-B has more immobile fraction than GFP-AWhich of the above-mentioned statements for GFP-A and GFP-B are correct?

75

PYP

LIFE SCIENCE PART C (DECEMBER 2019) 2019

Absorption spectra of L-tyrosine in acidic (continuous line) and basic (dotted line) medium was estimated and plotted on a graph as depicted below:Following interpretations were made:i. Change in the pH from acidic to basic results in shift in the lowest energy absorption maximum and decrease in the molar absorptivity.ii. Shifting of the absorption band to longer wavelength signifies a shift to lower energy, also known as red shift.iii. Shifting of the absorption band to shorter wavelength signifies a shift to higher energy, also known as blue shift.iv. Wavelength shift is always accompanied by change in intensity of the absorption band.Select the combination with correct interpretations.

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

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LIFE SCIENCE PART C (DECEMBER 2019) 2019

Difficulty distribution

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