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Previous Year Questions

TLS Online TPP Program

QUESTION ID:1

The following statements are made with regard to the optical activity of amino acids derived from natural proteins:
A. All alpha-amino acids have the D stereochemical configuration.
B. All L-amino acids have the (S) absolute configuration except cysteine, which has the (R) absolute configuration.
C. All D-amino acids have the (S) absolute configuration except cysteine, which has the (R) stereochemical configuration.
D. In the absolute configuration system, L-threonine and L-isoleucine are (2S, 3R)-threonine and (2S, 3S) -isoleucine diastereomers, respectively.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:2

The following statements are made about post-transcriptional processing:
A. RNA editing can occur via the deamination of cytosine residues, .leading to formation of uracil and thus a change in coding sequence.
B. The major spliceosomal complex mediates the removal of Group II introns.
C. Trans-splicing events seen in trypanosomes allow the formation of multiple gene products by bringing together ditTerent combinations of exons of three or more genes.
D. Capping of eukaryotic mRNAs occurs exclusively in the nucleus of the cell.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:3

Bacteriophage A proteins, CI and Cro are crucial reguliaiors of the lysogeny and lytic cycles of the bacteriophage. These proteins bind to the rightward operator region consisting of OR1, OR2, and OR3 (shown below).
Which one of the following statements about the regulation by CI and Cro proteins is CORRECT?

QUESTION ID:4

Given below is the list of viruses in Column X and their receptors in human host cells in Column Y.

Which one of the following options gives all correct matches between Column X and Column Y?

QUESTION ID:5

Given below are some statements that are associated with transgenic plants. Each statement has a blank space indicated by '_______'.
A. A transgenic plant with two functional copies of a transgene can segregate in a _____ ratio for the transgenic phenotype on self-pollination if the two genes are linked.
B. The ____ system can be used for removal of marker genes from transgenic plants.
C. The endogenous plant gene, ________ , can be used to engineer resistance to imidazolinone herbicides.
D . Variations in transgene expression levels between five independent transgenic lines generated  using the same T-DNA construct can be due to _______ .
Which one of the following options has the correct sequence of terms that can be used to fill in the blanks in the above statements (from A to D) such that all statements become true?

QUESTION ID:6

The figure below represents the fundamental and realised niche of two species.

Which one of the following options correctly identifies the fundamental niche and realised niche of any one of the species?

QUESTION ID:7

The following statements are potential explanations for the continued existence of genes that control eye development in eyeless cavefish.
A. They have inherited these genes from their ancestors and this remains even though they no longer have eyes.
B. In case of a possibility tl1at they return to tlle smface environment retention of vision would be advantageous, so evolution retains this trait.
C. Evolution can only lead to gain of a trait, not loss of a trait.
D. These genes are retained because of combined role of these genes with other sensory mechanisms.
Which one of the following options represents the combination of correct statements?

QUESTION ID:8

Males of a species of grasshopper produce loud calls to attract females. Most energy of these calls lie in the species-specific frequency, while other frequencies have much less energy. This is depicted in a power spectrum (plots with solid line in the figures below). Females find males by listening to and recognizing the species-specific call, and they are most sensitive to the species specific frequency. This is depicted using hearing threshold curves (plots in dashed lines in the figures below). This allows females to find even the softest calling males of their own species and ignore even the loud callers of other species, resulting in reproductive isolation.
Which one of the following figures represents the correct option for the hearing threshold (dashed lines) of females, given the power spectrum (solid lines) of male calls of this grasshopper species?

QUESTION ID:9

The following statements are made regarding materials transported through the phloem of a plant.
A. Only reducing sugars are translocated.
B. Non-reducing sugars are generally translocated.
C. Sucrose and raffinose are generally translocated.
D. Only D-glucose and D-fructose are translocated.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:10

The following is the life table of a natural population of a small annual succulent where 'x' is its life phase, 'lx' is its survivorship till that stage and 'dx' is its age specific mortality.
Which of the following options from the above life phases show the lowest age specific mortality rate?

QUESTION ID:11

Two batches of antibodies (Q and R) were generated for an antigen and affinities of both the antibodies were assayed using pure antigen. Given below are Scatchard plots obtained for the antibody-antigen binding assays and the inferences drawn upon Scatchard analysis.
A. Antibody Q is possibly a monoclonal while R is polyclonal
B. The curved nature of Scatchard plot for R indicates that it cross-reacts with the blocking reagent
C. The average affinity of R is more than affinity of Q to the antigen
D. Antibody Q is possibly IgA and R is IgG
E. The valency of the antibodies cannot be inferred from the Scatchard plots.
Select the option that groups all the correct inferences .

QUESTION ID:12

The figure below depicts the evolutionary tree of organisms based on characteristics that are depicted as numbers (i-iv).

Choose the option that correctly matches the characteristics to the numbers:

QUESTION ID:13

The theory of island biogeography has synthesized into theory the following concepts, except :

QUESTION ID:14

Following statements are made about fertilization occuring in sea urchins:
A. Chemoattraction of the sperm to the egg is mediated by sperm activating peptides like bindin.
B. Exocytosis of the sperm acrosomal vesicles and release of enzymes occur.
C. The capacitated sperm undergoes acrosome reaction.
D. The acrosome protein mediating the critical species-specific binding event is resact.
E. The slow block to polyspermy is accomplished by the cortical granule reaction.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:15

The diagram below depicts the relationship of land plants with some of the major apomorphies indicated.

Below is a list of apomorphies that have not been labeled on the tree above.

i. Intercalary growth of sporophyte

ii. Oil bodies

iii. Archegonium

iv. Leptoids

Which one of the following options correctly matches the apomorphies with their positions on the tree?

QUESTION ID:16

Following statements with respect to development in sea urchin were put forth:
A. The cell fates are determined both by autonomous and conditional modes of specification.
B. Large micromeres are conditionally specified.
C. Large micromeres produce paracrine and juxtacrine factors that specify the fates of their neighbours.
D. β-catenin is not required for the specification of the micromeres.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:17

Shown below are the CD spectra of a protein recorded under two different conditions.

From the options given below, select the one that is the best interpretation of the spectra.

QUESTION ID:18

Given below are some statements with blank spaces indicated by ' ___'.
A. A plasmid cloning vector digested with an enzyme (with a single restriction site in the plasmid) that generates 3' overhangs can be made blunt-ended using ______
B. DNA with a nucleotide composition of 30% A, 35% G, 20% C and 15% Tis most likely _________ .
C. Production of only truncated molecules of trans gene-derived mRNA in transgenic plants generated using a transgene from a prokaryotic source is most likely due to ____
D. ______ is a method for identifying the positions where  individual DNA-binding proteins attach to a genome.
Which one of the following options has the correct sequence of terms that can be used to complete the above statements (from A to D) such that all statements become true?

QUESTION ID:19

In an experiment, immunophenotyping of human blood cells was done to analyse the relative number of CD8+ T cells and CD4+ T cells. The following antibody-fluorochrome conjugates for staining different blood cells were available:
i. CD19-FITC forB lymphocytes
ii. CD8-CY7 PE for T lymphocytes
iii. CD4-Cy7 PE for T lymphocytes
iv. CD3-PE for T lymphocytes
v. DAPI for nucleus
Which one of the following options gives the correct sequence of antibody-fluorochrome conjugates, to be used to sort the relative abundance of CD8+ and CD4+ cells in the given blood sample by FACS?

QUESTION ID:20

Many species of birds call at dawn in temperate regions. The phenomenon is referred to as "Dawn Chorus". Several explanations have been proposed for this. Which one of the options is NOT a correct explanation for the occurrence of "Dawn Chorus"?

QUESTION ID:21

The following statements are made regarding the characteristic features of body temperature in humans:
A. The core body temperature varies least with the changes of environmenta l temperature.
B. During severe muscular exercise the rectal temperature may rise up to 40°C.
C. The oral temperature is relatively higher than the rectal temperature.
D. The core body temperature is highest at 6:00AM and lowest in the evening in humans who sleep at night and remain awake during day time.
E. The temperature of scrotum is regulated at 3 7°C.
F. In women, a rise of basal body temperature occurs immediately after ovulation.
Which one of the following options represents the INCORRECT combination of the statements?

QUESTION ID:22

In a tissue, cells are bound together by physical attachment between cell to cell or between cell to the extracellular matrix. The following are some of the characteristics of cell junctions:
A. Tight junctions are cell-cell junctions connecting the intermediate filament in one cell with that in the adjacent cell.
B. Desmosomes are cell-matrix anchoring junctions connecting actin filament in one cell to the extracellular matrix.
C. Gap junctions are channel-formingjunctions allowing the passage of small water-soluble molecules ±rom cell to cell.
D. Tight junctions are occluding junctions that seal the gap between two cells.
E. Hemidesmosomes are cell-matrix anchoring junctions connecting intermediate filaments in one cell to the extracellular matrix.
Which one of the following options represents the combination of ALL INCORRECT statements?

QUESTION ID:23

During water stress, ABA increases dramatically in leaves causing stomatal closure. Given below are the various events involved in this process.
A. Opening of plasma membrane Ca2+ permeable ion channels and elevation of cytosolic Ca2+
B. Activation of plasma membrane anion channels, efflux of anions and potassium ions.
C. Binding of ABA to cytosolic ABA receptor and inhibition of activity of Type 2C protein phosphatases (PP2Cs).
D. Phosphoqlation and activation of NADPH oxidases (RBOH) and formation of apoplastic ROS.
Which one of the following options represents the correct sequence of events involved?

QUESTION ID:24

Given below are the five experiments (A-E) showing effects of duration of the light and dark periods on flowering of the short-day plants (SDP) and long-day plants (LDP).

Which one of the following options represents the combination of all correct flowering responses?

QUESTION ID:25

Following statements are made regarding amphibian development:
A. Fibronectin plays an important role in enabling the mesodermal cells to migrate into the embryo.
B. Organizer secrete proteins that block the BMP signal, which allows the ectodermal cells to become epidermis.
C. Wnt signalling causes a gradient of β-catenin along the anterior-posterior axis of the neural plate, which appears to specify the regionalization of the neural tube.
D. The more ventral blastomeres in the endoderm have high expression of nodal-related proteins.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:26

The following represents selected AFLP bands (I to V) observed in parents (P1 and P2), F1 progeny and 20 doubled haploid (DH) progeny developed from the F1. DH are created through chromosome doubling of pollen grains in anther culture.
The following statements were made about the above AFLP bands:
A. Bands I and IV are allelic.
B. Bands II and V assort independently.
C. Band III is uninformative.
Which one of the following options represents a combination of all correct statements?

QUESTION ID:27

Following statements are made about the bacterial ribosomes and their functions:
A. Association of23S rRNA with 16S rRNA is essential to catalyze in vitro peptide bond formation using model substrates.
B. The 23S rRNA is necessary and sutiicient to catalyze in vitro peptide bond formation using model substrates.
C. Ribosome carries a polymerization activity.
D. The 16S rRNA is necessary and sufficient to catalyze in vitro peptide bond formation using model substrates.
Which one of the following options represents the combination of both correct statements?

QUESTION ID:28

The following statements were made about X-chromosome inactivation in humans:
A. Maternally-derive d X-chromosome has a greater chance of becoming inactivated in any given cell.
B. Both X-chromosomes are activated dming the process of oogenesis.
C. The XIST gene encodes for a single, long non-coding transcript, which binds with the X-chromosome and helps in its inactivation.
D. The XIST gene expression is required to initiate inactivation of X- chromosome, and also to maintain inactivation from one cell generation to the next.
E. Tsix transcription affects the abundance of Xist RNA in cis.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:29

Select the rare or endangered species which also have exceptionally low genetic variability, as documented by multi-locus molecular methods.

QUESTION ID:30

The aminoacyl-tRNA synthetases (AARSs) in an organism have evolved to catalyze aminoacylation of their cognate tRNAs

QUESTION ID:31

A founder population has an Aa heterozygous genotype with a frequency of 1, and no individual with either AA or aa genotypes. With repeated self-fertilization, the frequency of AA. Aa and aa after three generations will be :

QUESTION ID:32

Below are some of the proposed roles of reactive oxygen species (ROS) in plant defense.
A. H2O2 may be directly toxic to pathogens
B. In presence of iron, H2O2 gives rise to an extremely reactive hydroxyl radical.
C. H2O2 leads to induced biosynthesis of salicylic acid (SA).
D. H2O2 production is always delayed during incompatible interactions.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:33

In yeast, under anaerobic conditions, pyruvate is fermented to ethanol through two steps : decarboxylation of pyruvate to acetaldehyde and NADH-mediated reduction of acetaldehyde to ethanol. The mammalian liver also expresses alcohol dehydrogenase (Liver ADH: L-ADH). From the options given below, choose the one that best explains the physiological significance of L-ADH in the absence of fermentation in the liver.

QUESTION ID:34

The effects of stimulation of cholinergic vagal fibers on the pacemaker potential of the cells of sinoatrial (SA) node of heart and on the nodal impulse generation are suggested below:
A. The nodal cell membrane becomes depolarized.
B. The slope of the pacemaker potential is increased.
C. The K+ conductance of nodal cell membrane is decreased.
D. The depolarizing effect of 'h' current (Ih) on the membrane potential is slowed down due to the opening of G protein gated K+ channels.
E. The opening of Ca ++ cha1mels are slowed down due to the decreased cAMP level in the nodal cells.
Which one of the following options represents the combination of all correct statements?

QUESTION ID:35

Blood hemostasis is the interplay of several intrinsic and extrinsic factors. Deficiency of some of the blood clotting factors and their clinical manifestations are listed below.
Which one of the following options represents all correct matches?

QUESTION ID:36

The figure below depicts the absorption spectra of chlorophylls and carotenoid over a range of wavelengths.
Which one of the following combinations best describes A, B and C from the absorption spectra shown above?