Recent studies on Archaea suggest that life could have originated
a.
extraterrestrially and seeded through meteorite impacts.
b.
in shallow coastal areas.
c.
in deep hydrothermal vents..
Correct Answer
d.
in hot, terrestrial habitats.
Step-by-Step AI Explanation
Verified Method
Many early-diverging archaea are hyperthermophiles inhabiting deep-sea hydrothermal vents. The discovery of these organisms supports the hypothesis that life on Earth originated in deep-sea hydrothermal vents, which provided mineral-rich, chemically reducing environments with abundant thermal and chemical energy.
Q22mcq
If the ratio of the number of nonsynonymous to synonymous substitutions per site in protein coding gene is greater than one, it is an evidence of selection that is
a.
positive.
Correct Answer
b.
negative.
c.
neutral.
d.
random.
Step-by-Step AI Explanation
Verified Method
The ratio of non-synonymous substitutions per non-synonymous site ($d_N$) to synonymous substitutions per synonymous site ($d_S$) indicates the mode of natural selection acting on a protein-coding gene:
- $d_N / d_S > 1$: Positive (diversifying) selection favoring novel amino acid changes.
- $d_N / d_S = 1$: Neutral evolution.
- $d_N / d_S < 1$: Purifying (negative) selection acting to conserve the amino acid sequence.
Q23mcq
The following is the biochemical pathway for purple pigment production in flowers of sweet pea:
$$\text{Colourless Precursor 1} \xrightarrow{\text{Allele } A} \text{Colourless Precursor 2} \xrightarrow{\text{Allele } B} \text{Purple Pigment}$$
Recessive mutation of either gene A or B leads to the formation of white flowers. A cross is made between two parents with the genotype: $\text{AaBb} \times \text{aabb}$ Considering that the two genes are not linked, the phenotypes of the expected progenies are
a.
9 purple : 7 white
b.
3 white : 1 purple
Correct Answer
c.
1 purple : 1 white
d.
9 purple : 6 light purple : 1 white
Step-by-Step AI Explanation
Verified Method
In this biochemical pathway, both functional alleles $A$ and $B$ (at least one dominant allele at each locus, $A\_B\_$) are necessary to produce the purple pigment. Any genotype missing a dominant allele at either locus (i.e., $A\_bb$, $aaB\_$, or $aabb$) will fail to produce the pigment and result in white flowers.
The testcross $AaBb \times aabb$ yields four equally frequent progeny genotypes:
- $1/4\ AaBb$ (Purple)
- $1/4\ Aabb$ (White)
- $1/4\ aaBb$ (White)
- $1/4\ aabb$ (White)
Thus, the phenotypic ratio is 1 purple : 3 white (or 3 white : 1 purple).
Q24mcq
The frequencies of alleles 'A' and 'a' in a population at Hardy- Weinberg equilibrium are 0.7 and 0.3, respectively. In a random sample of 250 individuals taken from the population, how many are expected to be heterozygous?
a.
112
b.
81
c.
105
Correct Answer
d.
145
Step-by-Step AI Explanation
Verified Method
According to the Hardy-Weinberg principle:
- Frequency of allele $A$ ($p$) = $0.7$
- Frequency of allele $a$ ($q$) = $0.3$
The frequency of heterozygotes ($Aa$) is given by $2pq = 2 \times 0.7 \times 0.3 = 0.42$.
In a sample of $N = 250$ individuals, the expected number of heterozygotes is:
$$\text{Expected number} = 250 \times 0.42 = 105$$
Q25mcq
The transition to flowering in plants requires
a.
growth of plants under long- day conditions.
b.
growth of plants under short- day conditions.
c.
reprogramming of the shoot apical meristem.
Correct Answer
d.
synthesis of the flowering hormone florigen.
Step-by-Step AI Explanation
Verified Method
Floral transition fundamentally requires the reprogramming of the vegetative shoot apical meristem (SAM) into an inflorescence or floral meristem, altering gene expression patterns (such as activating floral identity genes like *AP1* and *LFY*). While photoperiod cues and florigen (FT protein) are common induction signals, not all plants require long-day or short-day conditions (e.g., day-neutral plants), but all undergo meristem reprogramming.
Q26mcq
In an altruistic act, if a donor sacrifices 'C' offspring which helps the recipient to gain 'B' offspring and the donor is related to the recipient by a coefficient $\gamma$, under which condition would kin selection favour this altruistic trait?
a.
$\text{B} > \text{C}$
b.
$\text{B} > \gamma\text{C}$
c.
$\gamma\text{B} - \text{C} = 0$
d.
$\gamma\text{B} - \text{C} > 0$
Correct Answer
Step-by-Step AI Explanation
Verified Method
According to Hamilton's Rule for kin selection, an altruistic trait is favored when:
$$\gamma B > C \implies \gamma B - C > 0$$
where $B$ is the reproductive benefit to the recipient, $C$ is the reproductive cost to the donor, and $\gamma$ (or $r$) is the coefficient of relatedness between the donor and recipient.
Q27mcq
Aneuploid females with only one X chromosome is a characteristic of individuals with
a.
Cri du chat syndrome
b.
Klinefelter syndrome
c.
Down syndrome
d.
Turner syndrome
Correct Answer
Step-by-Step AI Explanation
Verified Method
Turner syndrome is characterized by monosomy of the X chromosome ($45,X$), resulting in phenotypic females with short stature, webbed neck, and gonadal dysgenesis. Cri du chat syndrome is caused by a deletion on chromosome 5; Klinefelter syndrome is characterized by a $47,XXY$ karyotype in males; and Down syndrome is caused by trisomy of chromosome 21.
Q28mcq
Which of the following food crops has recently been genetically engineered to obtain edible vaccine to develop immunity against hepatitis B?
a.
Banana
b.
Maize
c.
Potato
Correct Answer
d.
Tomato
Step-by-Step AI Explanation
Verified Method
Potato (*Solanum tuberosum*) was among the first widely studied food crops genetically engineered to produce the Hepatitis B surface antigen (HBsAg) as an edible vaccine. Human clinical trials successfully demonstrated that consuming transgenic raw potatoes expressing HBsAg elicited protective mucosal and serum antibody responses against the Hepatitis B virus.
Q29mcq
The most commonly used method of estimating primary productivity of a pond involves measurement of the amount
a.
$\text{CO}_2$ Utilised
b.
autotroph biomass
c.
Oxygen released
Correct Answer
d.
Organic carbon
Step-by-Step AI Explanation
Verified Method
The light and dark bottle method (developed by Gaarder and Gran in 1927) is the standard and most commonly used technique to estimate primary productivity in aquatic ecosystems like ponds. It measures the change in dissolved oxygen concentration over time resulting from photosynthesis (oxygen released) and respiration.
Q30mcq
The area of allowed regions in the Ramachandran map will be least for
a.
Gly
b.
L-Ala
c.
L-Prol
d.
$\alpha$-methyl L-Valine
Correct Answer
Step-by-Step AI Explanation
Verified Method
The allowed regions in a Ramachandran plot depend on steric hindrance around the $\alpha$-carbon. Glycine has no $\beta$-carbon, giving it the largest allowed area. Proline is restricted by its pyrrolidine ring, but $\alpha$-methylated amino acids such as $\alpha$-methyl L-valine (having both a methyl group and a bulky isopropyl group attached to the $\text{C}_\alpha$) suffer from extreme steric clash between the $\alpha$-methyl group, side chain, and peptide backbone, severely restricting $\phi$ and $\psi$ angles to an even smaller conformational space than proline.
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Small RNAs with internally complementary sequences that form hairpin-like structure, synthesized as percursor RNAs and cleaved by endonucleases to form short duplexes are called
a.
snRNA
b.
mRNA
c.
tRNA.
d.
miRNA.
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A much greater proportion of energy fixed by autotrophs is transferred to the herbivore level in the open ocean ecosystem than in a forest ecosystem because
a.
aquatic autotrophs are small
b.
aquatic herbivores are more efficient feeders
c.
terrestrial autotrophs are less efficient feeders
d.
terrestrial autotrophs have more indigestible tissues
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Release of nutrients, oxidants or electron donors into the environment to stimulate naturally occurring microoganisms to degrade a contaminant, is referred to as
a.
biostimulation
b.
phytoremediation
c.
bioaugmentation
d.
bioremediation
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Yeast artificial chromosome (YAC) vectors contain selectable markers. Loss of which marker at the cloning site distinguishes the re-ligated YACs from the original vector marker?
a.
TRP-1
b.
SUP4
c.
URA3
d.
CEN
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$\text{Na}^+$-$\text{K}^+$ ATPase is a tetramer of $2\alpha$ and $2\beta$ subunits. On which of the following subunits are the $\text{Na}^+$ and $\text{K}^+$ binding sites present?
a.
both on $\alpha$
b.
both on $\beta$
c.
$\text{Na}^+$ on $\alpha$ and $\text{K}^+$ on $\beta$
d.
$\text{Na}^+$ on $\beta$ and $\text{K}^+$ on $\alpha$
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The $\mu$ and $\sigma$ of wing length (a normally distributed parameter) in a population of fruitflies are $4$ and $0.2\text{ mm}$. respectively. In a random sample of $400$ fruitflies, how many individuals are expected to have wing lengths greater than $4.4\text{ mm}$?
a.
20
b.
64
c.
10
d.
336
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A culture of an *E.coli* strain that is lysogenic for phage lambda is grown at $32^\circ\text{C}$. Induction of the prophage from the host chromosome will occur when the culture is exposed to
a.
$40^\circ\text{C}$
b.
Ultra violet radiation
c.
Infra-red radiation
d.
Wild type *E. coli* culture
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Both halophytes and glycophytes compartmentalize cytotoxic ions into the intracellular compartment or actively pump them out of the cell to the apoplasts with the help of membrane transport proteins. Among these, the $\text{Na}^+\text{-H}^+$ antiporter, NHX1, is localized in
a.
the plasma membrane.
b.
chloroplast (inner envelope).
c.
mitochondria (outer membrane).
d.
Tonoplast.
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You are studying the binding of proteins to the cytoplasmic face of cultured liver cells and have found a method that gives a good yield of inside-out vesicles from the plasma membrane. Unfortunately, your preparations are contaminated with variable amounts of right-side-out vesicles. Nothing you have tried avoids this contamination. Somebody suggests that you pass the vesicles over an affinity column made of lectin coupled to Sepharose beads. What is the rational of this suggestion?
a.
Right-side-out-vesicles wIll be lysed by lectin coupled to Sepharose beads.
b.
Right-side-out-vesicles will simply bind to the lectin coupled Sepharose beads.
c.
Lectin will bind to the carbohydrate residues present only on the inside out vesicles.
d.
Lectin will bind to only glycoproteins and glycolipids present on the inside-out vesicles.
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The overall length of the cell cycle can be measured from the doubling time of a population of exponentially proliferating cells. The doubling time of a population of mouse L cells was determined by counting the number of cells in samples of culture at various times. What is the overall length of the cell cycle in mouse L cells?
a.
$30\text{ h}$
b.
$20\text{ h}$
c.
$10\text{ h}$
d.
$40\text{ h}$
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Using molecular clock, it was estimated that two species A and B must have diverged from their common ancestor about $9 \times 10^6$ years ago. If the rate of divergence per base pair is estimated to be $0.0015$ per million years, what is the proportion of base pairs that differ between the two species now?
a.
$0.0270$
b.
$0.0135$
c.
$0.00017$
d.
$0.0035$
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A protein in $100\text{ mM }\text{KCl}$ solution was heated and the observed $\text{T}_\text{m}$ (midpoint of unfolding) was $60^\circ\text{C}$. When the same protein solution in $500\text{ mM }\text{KCl}$ was heated, the observed $\text{T}_\text{m}$ was $65^\circ\text{C}$. What is the most probable reason for this increase in $\text{T}_\text{m}$?
a.
Hydrophobic interaction is increased and electrostatic repulsion is decreased
b.
Hydrophobic interaction is decreased and electrostatic repulsion is increased
c.
Hydrogen bonding is increased
d.
Van der Waals interaction is increased
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During receptor-mediated endocytosis, apolipoprotein B on the surface of a LDL particle binds to the LDL-receptor present in coated pits containing clathrin. The receptor-LDL complex is internalized by endocytosis, trafficked to lysosomes and the LDL-receptor is finally recycled. A patient reports with familial hypercholesterolemia. This could be due to
a.
mutation in the LDL molecule.
b.
defect in LDL-receptor recycling.
c.
mutation in the LDL-receptor.
d.
defect in cholesterol binding with its receptor.
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Budding yeast cells that are deficient for Mad2, a component of the spindle-attachment-check point, are killed by treatment with benomyl, which causes microtubules to depolymerise. In the absence of benomyl, however, the cells are perfectly viable. Which explanation out of the following is able to justify this observation?
a.
In the absence of benomyl, the majority of spindles forms normally and the spindle-attachment checkpoint (Mad2) plays no role.
b.
In the presence of benomyl, the majority of spindles form normally and Mad2 plays critical role in cell survival.
c.
Other than the role in cell survival, microtuble depolymerization affects oxidative phosphorylation in the absence of Mad2.
d.
Benomyl also affects protein synthesis in the absence of Mad2.
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Eukaryotic genomes are organized into chromosomes and can be visualized at mitosis by staining with specific dyes. Heat denaturation followed by staining with Giemsa produced alternate dark and light bands. The dark bands obtained by this process are mainly
a.
AT -rich and gene rich regions.
b.
AT -rich and gene desert regions.
c.
GC-rich and gene rich regions.
d.
GC-rich and gene desert regions.
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An amino acid contains no ionizable group in its side chain (R). It is titrated from pH 0 to 14. Which of the following ionizable state is not observed during the entire titration in the pH range 0 – 14?
A researcher has isolated a restriction endonuclease that cleaves at only one specific 10 base pair site.
(i) Would this enzyme be useful in protecting cells from viral infections, given that a typical viral genome is $5\times 10^4$ base pairs long?
(ii) Restriction endonucleases are slow enzymes with turnover number of $1\text{ s}^{-1}$. Suppose the isolated endonuclease was faster with turnover numbers similar to those for carbonic anhydrase ($10^6\text{ s}^{-1}$), would this increased rate be beneficial to host cells, assuming that the fast enzymes have similar levels of specificity?
The correct combination of answer is
a.
(A) : No (B) : Yes
b.
(A) : No (B) : No
c.
(A) : Yes (B) : No
d.
(A) : Yes (B) : Yes
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Lac repressor inhibits expression of genes in lac-operon whereas purine biosynthesis is repressed by the Pur repressor. The two proteins have 31% identical sequences and have similar three-dimensional structures. The gene regulatory properties of these proteins differ in relation to
(i) binding of small molecules to the repressor.
(ii) presence of recognition sites on the genome.
(iii) oligomeric nature of the repressor.
(iv) DNA binding property.
The correct statements are
a.
A and B
b.
A, B and C
c.
A and C
d.
B, C and D
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An $\alpha$-helix in a peptide or protein is characterized by hydrogen bonds and characteristic dihedral angles. Choose the right combination.
a.
Hydrogen bonding between the amide CO of residue i and amide NH of residue i + 4. Dihedral angles in the region $\phi = -50^\circ$, $\psi = -60^\circ$
b.
Hydrogen bonding between amide NH of residue i and amide CO of residue i + 4. Dihedral angles in the region of $\phi = -50^\circ$, $\psi = -60^\circ$
c.
Hydrogen bonding between the amide CO of residue i and amide NH of residue i + 4, Dihedral angles in the region of $\phi = -50^\circ$, $\psi = +60^\circ$
d.
Hydrogen bonding between the amide CO of residue i and amide NH of residue i + 3. Dihedral angles in the region of $\phi = -50^\circ$, $\psi = -60^\circ$
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Mouse bone marrow cells were fractionated to derive stem cells antigen $1^+$ (Sca $1^+$) cells. These cells were cultured with interleukin-3, or granulocyte macrophage colony stimulating factor, or macrophage colony stimulating factor, or granulocyte colony stimulating factor. Most numerous and varied colonies were obtained in the culture stimulated with
a.
Interleukin-3
b.
Granulocyte-macrophage colony stimulating factor
c.
Macrophage colony stimulating factor
d.
Granulocyte colony stimulating factor
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Two E. coli cultures A and B are taken. Culture A was earlier grown in the presence of optimum concentration of gratuitous inducer IPTG. Both the cultures are now used to inoculate fresh medium containing sub-optimal concentration of gratuitous inducer. It was observed that culture B was unable to utilize lactose, whereas culture A did so efficiently. The reason behind this is
a.
pretreatment with IPTG has resulted in a mutation as a result of which lac operon is constitutively expressed
b.
IPTG has made the cell membrane more porous to small molecules and so lactose is taken up more efficiently by A as compared to B.
c.
in culture A, lactose permease was induced to a high level, during pretreatment with IPTG, which allowed the preferential uptake of lactose.
d.
in culture A, IPTG activated a receptor which bound lactose more efficiently, thereby triggering a signal.
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Cancer causing genes can be functionally classified into mainly three types: (i) genes that induce cellular proliferation, (ii) tumor suppressor genes, (iii) genes that regulate apoptotic pathway.
Epstein-Barr virus that causes cancer by modulating apoptotic pathway, contains a gene having sequence homology with which of the following genes?
a.
bax
b.
bcl-2
c.
p53
d.
caspase-3
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It has been observed that in 5-10% of the eukaryotic mRNAs with multiple AUGs, the first AUG is not the initiation site. In such cases, the ribosome skips over one or more AUGs before encountering the favourable one and initiating translation. This is postulated to be due to the presence of the following consensus sequence (s):
(i) CCA CC AUG G
(ii) CCG CC AUG G
(iii) CCG CC AUG C
(iv) AAC GG AUG A
Which of the following sequence sets related to the above postulations is correct?
a.
A and B
b.
A and C
c.
C and D
d.
B and D
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The values of $\text{T}_\text{m}$ (midpoint of denaturation), $\Delta \text{H}_\text{m}$ (enthalpy change at $\text{T}_\text{m}$) and $\Delta \text{C}_\text{p}$ (constant pressure heat capacity change) of protein are measured in differential scanning colorimeter. $\Delta \text{G}_\text{D}(\text{T})$, the Gibbs free energy change at any temperature $\text{T}(\text{K})$ can be estimated using the following form of the Gibbs Helmholtz equation with the values obtained from these measurements:
$$\Delta \text{G}_\text{D}(\text{T}) = \Delta \text{H}_\text{m}\left(\frac{\text{T}_\text{m}-\text{T}}{\text{T}_\text{m}}\right) - \Delta \text{C}_\text{p}[\text{T}_\text{m}-\text{T}+\text{T}\ln(\text{T}/\text{T}_\text{m})]$$
The stability curve for the protein simulated using the observed thermodynamic values is given below:
The shape of the stability curve is due to
a.
Hydrogen bonding and electrostatic interactions only
b.
Van der Waals and electrostatic interactions only
c.
Only electrostatic interactions
d.
Only hydrophobic interactions
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Toll like receptor 4 is associated with responsiveness to LPS, an endotoxin that causes lethal endotoxic shock. The mice deficient in Toll like receptor 4 and BALB/c mice were injected with *Escherichia coli*. In addition, some BALB/b mice were also injected with the same bacteria alone or with anti interleukin 10 (IL 10) antibody. The mice resistant to the lethal effect of bacteria were
a.
BALB/b mice receiving the bacteria
b.
BABL/b mice receiving the bacteria and the anti IL-10 antibody
c.
Mice deficient in Toll like receptor
d.
BALB /c mice receiving the bacteria
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Presence of circular mRNAs for a specific protein in an eukaryotic cell reflects a rapid rate of synthesis of that protein.
Following mechanisms are suggested:
(i) eIF-4G and PABP promote this process through 5'-3' interaction of mRNA.
(ii) ribosomes are less active in recognizing circular mRNA.
(iii) PABP and eIF-4A promote this process.
(iv) ribosomes can reinitiate translation without being disassembled.
Which of the following is correct?
a.
A and D
b.
B and D
c.
A and C
d.
B and C
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siRNAs and miRNAs are used for achieving gene silencing. Although, major steps are similar there are distinct differences in the key players of the two processing pathways. Following statements relate to some characteristic features of gene silencing.
(i) Both siRNAs and miRNAs are processed by cytoplasmic endonuclease Dicer.
(ii) 'Drosha' is needed for processing miRNAs and precursor siRNAs.
(iii) Both siRNAs and miRNAs show association with Argonaute protein.
(iv) Both the processing pathways involve RISc complex.
Which of the following combinations is NOT correct?
a.
A and C
b.
C and D
c.
A and B
d.
D and A
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Glucose is mobilized in muscle when epinephrine activates $G_{\alpha s}$. In an experiment in which muscle cells were stimulated with epinephrine, glucose mobilization was observed even after withdrawal of epinephrine. This could be
a.
due to the presence of a cAMP phosphodiesterase inhibitor.
b.
very low rates of cyclic AMP formation.
c.
due to the presence of a cAMP phosphodiesterase activator.
d.
due to the absence of protein kinase A.
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In eukaryotic chromatin, $30\text{ nm}$ fiber (solenoid) can open up to give rise to two kinds of chromatin. In one type (A), the promoter of a gene within the open chromatin is occupied by a nucleosome whereas in the other (B), the promoter is occupied by histone H1. The following possibilities are suggested.
(i) The gene in (A) is repressed.
(ii) The gene in (B) is repressed.
(iii) The gene in (A) is active.
(iv) The gene in (B) is active.
Which of the following sets is correct?
a.
A and D
b.
A and B
c.
B and D
d.
C and D
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Intracellular pathogens like \textit{Mycobacteria}, \textit{Salmonella}, \textit{Leismania} and \textit{Listeria} survive in macrophages by modulating host cellular machinery. In order to study the fate of these intracellular pathogens in macrophages, cells were labeled with lysotracker Red arid infected with GFP labeled organisms. After 2 hours at $37^\circ\text{ C}$, cells were fixed, stained with anti-transferrin receptor antibody and probed with secondary antibody conjugated blue dyes. Cells were viewed under confocal microscope Observation: GFP labeled mycobacteria, \textit{Salmonella} and \textit{Listeria} were localized in the same compartment labeled with blue dyes; whereas GFP \textit{Leishmania} co-localize with red labeled compartment Which of the following statement is true based on these observations?
a.
Mycobacteria, \textit{Salmonella} and \textit{Listeria} reside in the lysosomes
b.
\textit{Leishmania} reside in lysosome like compartment
c.
\textit{Leishmania} reside in compartment which bears characteristics of early endocytic compartment
d.
\textit{Mycobacteria}, \textit{Salmonella} and \textit{Listeria} lyse the phagosomal membrane and reside in cytosol
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Macrophages were collected from BALB/c mice, CD40 deficient mice, CD86 deficient mice and ICAM-1 deficient mice. These macrophages were co-cultured with LCMV peptide specific T cells in presence of the LCMV peptide for three days. The cells were recovered and co-cultured with BALB/c derived macrophages in presence of the peptide. During the last twelve hour of the co-culture, $^{3}\text{H}$-thymidine was added to the cultures. The cells were harvested and $^{3}\text{H}$-thymidine incorporation was assessed. The highest incorporation was observed in
a.
BALB/c macrophage T cell co-culture
b.
CD40-deficient macrophage T cell co-culture
c.
CD86-deficient macrophage T cell co-culture
d.
ICAM-1-deficient macrophage T cell co-culture
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Genetic studies demonstrated that TBP mutant cell extracts are deficient in transcription of genes from all three promoters viz. class I, II and III. Following statements describe characteristic features of TBP.
(i) TBP is considered as an universal basal transcription factor.
(ii) TBP is not required for transcription of archaeal genes.
(iii) TBP is involved in recognizing TATA box.
(iv) TBP operates at all promoters regardless of their TATA content.
Which of the following combinations is NOT correct?
a.
A and D
b.
C and D
c.
B and D
d.
A and C
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cAMP signalling plays a very important role in the development and differentiation of Dictyostelium discoideum. This morphogen' is synthesized by different adenyl cyclases expressed at different stages of its life cycle. The following statements (AD) refer to the effect of mutations in different adenyl cyclase genes:
A. aca deficient cells can be allowed to aggregate by exposing them to pulses of cAMP.
B. acb deficient cells would form normal fruiting bodies and the spores can germinate when exposed to favourable conditions.
C. acg deficient cells develop normally and the spores germinate in the spore head itself.
D. spores formed from the acg deficient cells will germinate irrespective of the osmotic conditions.
Which of the above statements are correct?
a.
A and D.
b.
A only.
c.
A and B.
d.
C and D.
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Fill in the blanks (A, B, C and D) in the following statements with a proper combination of m, n, o, p.
Where in
m represents -longer;
n represents-shorter;
o represents-prevents;
p represents-induces.
Short day (SD) plants flower when night lengths are _____ A _____ than a critical dark period. Interruption of the dark period by a brief light treatment _____ B _____ flowering in SD plants. Long day (LD) plants flower when night length is _____ C _____ than a critical period. Shortening of the night with a brief light treatment _____ D _____ flowering in LD plants.
a.
A - m, B - o, C - n, D - p
b.
A - n, B - p, C - m, D - o
c.
A - n, B - o, C - m, D - p
d.
A - m, B - p, C - n, D - o
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The total variance in a phenotypic character can be split into two components- genetic ($V_G$) and environmental ($V_E$). The heritability of a phenotypic trait can be expressed quantitatively as heritability coefficient ($h^2$) which is calculated as $h^2=$
a.
$V_G - V_E$
b.
$V_E / V_G$
c.
$V_G / (V_G + V_E)$
d.
$V_G / (V_G - V_E)$
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Mutations in CONSTANS (CO) of Arabidopsis thaliana results in late flowering phenotype. Transcript levels of CO were determined in long day and short day seedlings. Which of the following would likely represent the transcript profile of CO?
a.
1
b.
2
c.
3
d.
4
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Following are some statements for synthesis of secondary metabolites in plants.
A. Terpenes are synthesized by shikimic acid pathway and mevalonic acid pathway
B. Alkaloids are nitrogen containing compounds and are synthesized by shikimic acid pathway
C. Phenolic compounds are synthesized by shikimic acid pathway and mevalonic acid pathway
D. Both alkaloids and terpenes are synthesized by mevalonic acid pathway and MEP pathway
Which of the following combinations of the above statements are true?
a.
A and D
b.
A and C
c.
B and C
d.
B and D
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During early cleavage of *Caenorhabditis elegans* embryos, each asymmetrical division produces one founder cell which produces differentiated descendants and one stem cell. The very first cell division produces one anterior founder cell, namely AB and one posterior stem cell, namely P1. When these blastomeres are experimentally separated and allowed to proceed further with development, one could get the following possible outcomes:
(a) P1 cell would develop autonomously while the AB would show conditional development.
(b) P1 cells would show conditional development while AB would show autonomous development.
(c) Both would show autonomous specification and result in mosaic development.
(d) Both would show conditional specification and result in regulative development.
a.
P1 cell would develop autonomously while the AB would show conditional development.
b.
P1 cells would show conditional development while AB would show autonomous development.
c.
Both would show autonomous specification and result in mosaic development.
d.
Both would show conditional specification and result in regulative development.
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In case of sea urchin, which of the following is the correct sequence of events taking place during the interaction of sperm and egg?
a.
Chemoattraction of sperm to the egg by soluble molecules secreted by the egg $\rightarrow$ exocytosis of the sperm acrosomal vesicle to release its enzymes $\rightarrow$ binding of the sperm to the extracellular matrix of the egg $\rightarrow$ passage of sperm through this extracellular matrix $\rightarrow$ fusion of egg and sperm cell membranes.
b.
Chemoattraction of sperm to the egg by soluble molecules secreted by the egg $\rightarrow$ binding of the sperm to the extracellular matrix of the egg $\rightarrow$ exocytosis of the sperm acrosomal vesicle to release its enzymes $\rightarrow$ passage of sperm through this extracellular matrix $\rightarrow$ fusion of egg and sperm cell membranes.
c.
Chemoattraction of sperm to the egg by soluble molecules secreted by the egg $\rightarrow$ binding of the sperm to the extracellular matrix of the egg $\rightarrow$ passage of sperm through this extracellular matrix $\rightarrow$ exocytosis of the sperm acrosomal vesicle to release its enzymes $\rightarrow$ fusion of egg and sperm cell membranes.
d.
Chemoattraction of sperm to the egg by soluble molecules secreted by the egg $\rightarrow$ passage of sperm through this extracellular matrix $\rightarrow$ binding of the sperm to the extracellular matrix of the egg $\rightarrow$ exocytosis of the sperm acrosomal vesicle to release its enzymes $\rightarrow$ fusion of egg and sperm cell membranes.
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The time taken for atrial systole and diastole in a normal heart are $\text{t}_{\text{as}}$ and $\text{t}_{\text{ad}}$ seconds, respectively. If ventricular systole takes $\text{t}_{\text{vs}}$ seconds, calculate the ventricular diastolic time (seconds)
A patient undergoes liver transplantation and during the course of post-operative treatment, becomes susceptible to infection. The patient can be treated in two different modes and can have alternative outcomes. Which of the following statements is correct?
a.
Treatment with immuno-stimulatory drugs reducing the infection but rejecting the transplant
b.
Treatment with immune-stimulatory drugs reducing the infection and retaining the transplant
c.
Treatment with antibiotics reducing the infection but retaining the transplant
d.
Treatment with antibiotics reducing the infection but rejecting the transplant
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The dependence of the rate of sucrose uptake with respect to sucrose concentration in plant cell was studied and data are shown in the following graph.
From the above data it can be inferred that:
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When F1 female *Drosophila* of the genotype $a^+ab^+bc^+c$ is test crossed, the following progenies were obtained:
The progeny has been shown as classes derived from the female gamete Statements A to F as given below are conclusions derived from the above result
A. Genes a and b are linked in cis
B. Genes a and b are linked in trnas
C. Genes a and b are linked in cis while b and c are linked in trans
D. The genotype of the parents are $a^+a^+b^+b^+$ and $aabb$
E. The genopyte of the parents are $a^+a^+bb$ and $aab^+b^+$
F. Genes a and b are 10 cM apart
Which of the above statements are correct?
a.
C alone
b.
A, E and F
c.
B, E and F
d.
A, D and F
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Monoclonal antibodies (mAb) can be potentially used as therapeutic agents. The major advantage is that they can specifically target aberrant cells. However, there is a practical difficulty. Monoclonal are raised in mouse and therefore it is expected that an immune reaction will develop if these are injected into humans. It is therefore necessary to humanize monoclonal antibody by
a.
Expressing the genes for the mAb in cultured human cells and isolating the mAb from these cells
b.
Replacing the Fc region of a mAb with one derived from a human IgG
c.
Replacing $\text{C}_\text{L}$ and $\text{C}_\text{H}$ regions of the mAb with that obtained from human IgG
d.
Taking a human IgG and replacing the CDRs by those derived from the mouse mAb
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The following is a hypothetical pathway for the development of wild type (red) eye colour in an insect:
Enzyme A and B are encoded by the genes $\text{a}^+$ and $\text{b}^+$, respectively.
The following statements are made regarding inheritance of the genes involved in the development of eye colour
A. When two heterozygous individuals of the genotype $\text{a}^+\text{ab}^+\text{b}$ are mated, progenies with red, orange, brown and white eye colour will be observed irrespective of whether the genes are independently assorting or showing incomplete linkage.
B. When two heterozygous individuals of the genotype $\text{a}^+\text{ab}^+\text{b}$ are mated, progenies with red, orange, brown, and white eye colour will be observed in a ratio of $9 : 3 : 3 : 1$, when the genes are independently assorting.
C. When an heterozygous individual of the genotype $\text{a}^+\text{b}/\text{ab}^+$ is test crossed, progenies with red and white eye colour will be more in number. D. When an heterozygous individual of the genotype $a^+b/ab^+$ is test crossed, progenies with orange and brown eye colour will be more in number.
Which of the above statements is true?
a.
A and C
b.
B and C
c.
A, B and C
d.
A, B and D
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Mendel crossed tall pea plants with dwarf ones. The F1 plants were all tall. When these F1 plants were selfed to produce F2 generation, he got a 3:1 tall to dwarf ratio in the offspring. What is the probability that out of three plants (of F2 generation) picked up at random two would be dwarf and one would be tall?
a.
$3/4$
b.
$3/8$
c.
$9/64$
d.
$9/32$
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Two new plant species, A and B, were described in 1872. Subsequently it was found that the type for species A was never designated and for species B there was one specimen designated as type but missing. As per International Code of Botanical nomenclature (ICBN), typification should be
a.
neotype for A only.
b.
neotype for A and lectotype for B.
c.
neotypes for both A and B.
d.
lectotype for both A and B.
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Proteins in the cells can be visualized by the following methods:
A. Express the gene (coding for the said protein) as a fusion with the green fluorescence protein (GFP) and directly visualize under a fluorescence microscope
B. Express the gene (coding for the said protein) as a fusion with the $\beta$-galactosidase gene (lac Z) and directly visualize under a phase contrast bright field microscope
C. A fluorescence tagged antibody raised against the said protein could be used for visualization in a fluorescence microscope
D. Over express the protein and directly visualize it under a scanning electron microscope
Which of the following methods you would choose to visualize a protein in a living cell?
a.
A only
b.
A and C only
c.
A and B only
d.
D only
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Affected individuals from the pedigree given below are suffering from albinism, an autosomal recessive disease. Identify the confirmed carrier individuals in their pedigree assuming that the members coming from outside the family are homozygous for the dominant allele.
a.
III-2, III-3, III-5, III-6, II-1, II-3 and II-6
b.
III-2, III-3, III-5, III-6, II-2, II-4, II-5 and I-2
c.
III-2, III-3, III-5, III-6, II-2, II-4 and II-5
d.
III-1, III-4, III-7, II-2, II-4 and II-5
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Primary production in aquatic ecosystem is measured using Light-and -Dark-Bottle technique. In this method, as an indirect measure of photosynthetic production, dissolved oxygen concentration of the pond water enclosed in a BOD bottle is measured initially (I) and after a fixed duration of incubation in a light bottle (L) and a dark bottle (D). Then, the gross and net primary productions are estimated is
a.
(L-D) and (L-I), respectively.
b.
(L-I) and (L-D), respectively.
c.
(L-I) and (I-D), respectively.
d.
(L-D) and (I-D), respectively.
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Gause’s Competitive exclusion’ principle states that two species with identical niches cannot coexist indefinitely. Which of the following statements is the most appropriate regarding the validity of the principle?
a.
It depends on how one defines niche.
b.
There are in nature many instances of continued coexistence of closely related species.
c.
The principle is universally true.
d.
It does not predict the outcome where, both the species are eaually strong competitors.
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In a lake ecosystem, bottom-up effects (B) refers to control of a lower trophic level by the higher trophic levels and top down effects (T) refer to the opposite. In a lake with three trophic levels - Phytoplankton (P), Zooplankton (Z) and Carnivore (C).
a.
P and C are controlled by B, and Z is controlled by T
b.
P, Z and C are all controlled by T
c.
P is controlled by B, Z is controlled by T and C is controlled by B
d.
P is controlled by T, Z is controlled by B and C is controlled by T
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An organism has the following architectural pattern:
(i) multicellular with germ layers
(ii) a coelom derived from the mesoderm
(iii)primary bilateral symmetry with secondary radial symmetry
(iv)presence of endoskeletal plates Such an organism is most likely to
(A) have mesohyl as its connective tissue.
(B) undergo torsion, whereby the mouth and anus are properly oriented.
(C) be devoid of a brain but have calcareous spicules.
(D) have comb plates to help in locomotion.
Which of the following is true?
a.
A and C
b.
C only
c.
D only
d.
B and C
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The graph below shows the relationships of per capita population growth rate ($r$), fecundity ($b$) and age at first reproduction ($\alpha$) in a animal species.
What is the important conclusion to be drawn from the graph?
a.
The later the age of first reproduction, the lower is the population growth rate achieved.
b.
The population growth rate decreases as first reproduction is postponed to a later stage, regardless of the fecundity.
c.
At any $\alpha$, the higher the fecundlity, the higher is the population growth rate achieved.
d.
As the age at first reproduction is postponed further, the benefits of increasing fecundity on the population growth rate become progressively negligible.
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An animal was first maintained in a constant environmental condition for several days until a consistent biological rhythm (B) was established. The animal was then exposed to an experimental physical rhythm (E). Which modulates the phase an period of B. However, upon withdrawal, E, the B gradually regained its pattern of pre-exposure condition. From these observations which one or more of the following should be the most logical inference ?
A. E is a Zeitgeber
B. E is a masking agent
C. E cause entrainment of B
D. B is a conditioned to E
The correct answer is
a.
A and C
b.
B and D
c.
B only
d.
D only
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Shown in the graph below are the fitness costs and benefits of four alternatives behavioural phenotypes (P, Q, R, S). Given sufficient evolutionary time, which phenotype(s) is likely to evolve as an adaptation?
a.
Q and R
b.
Q only
c.
P, Q and R
d.
S only
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The following geological eras mark the advent of important events in the history of earth - origin of terrestrial plants, origin of mammals and break up of the land mass Pangaea:
(a) Early Cambrian (b) Late Devonian (c) Late Cretaceous (d) Late Jurassic
Identify the correct match of the events with the geological era
a.
Origin of terrestrial plants - (c); Origin of mammals (d); Break-up of Pangaea - (a)
b.
Origin of terrestrial plants - (b); Origin of mammals (d); Break up of Pangaea -(c)
c.
Origin of terrestrial plants - (d); Origin of mammals (c); Break up of Pangaea -(b)
d.
Origin of terrestrial plants - (b); Origin of mammals (c); Break up of Pangaea -(d)
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Industrial products in which bacteria are employed for production are shown in the following table:
\begin{tabular}{|l|l|}
\hline
I. List of products & II. Microorganims \\
\hline
A. 2,3-Butane diol & (i) Leuconostoc \\
B. Dextran & (ii) Brevibacterium \\
C. Glutamic acid & (iii) Bacillus polymyxa \\
D. Cobalamine & (iv) Propionibacterium \\
\hline
\end{tabular}
The correct combinations are
a.
A - iii; B - i; C - ii; D - iv
b.
A - i; B - ii; C - iii; D - iv
c.
A - iii; B - ii; C - iv; D - I
d.
A - ii ; B - iii; C - iv; D - i
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Insertion lambda vectors are used to create cDNA libraries, In some insertion vectors, the site of insertion is within the cI gene. The, recombinants which are $\text{cI}^-$ can then be screened by plating on E. coli hfl. The gene hfl encodes a protease that controls lytic-lysogeny decision through which mechanism?
An experiment was designed to find out the relation between DNA uptake and transformation efficiency. $^{32}\text{P}$ labelled genomic DNA from Bacillus subtilis (A) and cold genomic DNA from Clostridium jejeuni (B) mixed in various proportions was used to transform Bacillus subtilis. The results obtained are tabulated below
The following interpretations (A to D) could be made
(i) The transformation is dependent on recombination between homologous sequences.
(ii) Cells did not distinguish between homologous or heterologous sequences for uptake of DNA.
(iii) DNA uptake is based on specific receptors
(iv) DNA degradation dictates transformation efficiency
Which of the following interpretations are correct?
a.
A and B
b.
A and C
c.
C and D
d.
A and D
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When a wrist blastema from a recently cut Axolotl forelimb is placed on a host hindlimb cut at the mid thigh level, it will generate only a wrist. The host (whose own hind limb was removed) will fill the gap and regenerate the limb upto the wrist. However if the donor blastema is treated with retinoic acid on grafting, the wrist blastema will regenerate a complete limb and will not allow the host to fill the gap. This happens because retinoic acid
a.
helps in proximalization of the blastema and activates the Hox genes differentially across the blastema.
b.
helps in the distalization of the blastema and activates the Hox genes differentially across the blastema.
c.
helps block the receptors of FGF essential for limb development
d.
helps vigorous proliferation of the cells at the cut surface.
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