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CSIR Exam Paper - Life Sciences
1. In India, brown antlered deer (sangai) is found only in the floating landmasses of
(1) Wular lake.
(2) Sasthamkotta lake.
(3) Dal lake.
(4) Lok Tak lake
2. 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 Na+-H+ antiporter, NHX1, is localized in
(1) the plasma membrane.
(2) chloroplast (inner envelope).
(3) mitochondria (outer membrane).
(4) Tonoplast.
3. 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?
(1) Right-side-out-vesicles wIll be lysed by lectin coupled to Sepharose beads.
(2) Right-side-out-vesicles will simply bind to the lectin coupled Sepharose beads.
(3) Lectin will bind to the carbohydrate residues present only on the inside out vesicles.
(4) Lectin will bind to only glycoproteins and glycolipids present on the inside-out vesicles.
4. 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
(1) AT -rich and gene rich regions.
(2) AT -rich and gene desert regions.
(3) GC-rich and gene rich regions.
(4) GC-rich and gene desert regions.
5. 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
A) binding of small molecules to the repressor.
B) presence of recognition sites on the genome.
C) oligomeric nature of the repressor.
D) DNA binding property.
The correct statements are
(1) A and B
(2) A, B and C
(3) A and C
(4) B, C and D
6. 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
(1) pretreatment with IPTG has resulted in a mutation as a result of which lac operon is constitutively expressed
(2) IPTG has made the cell membrane more porous to small molecu1es and so lactose is taken up more efficiently by A as compared to B.
(3) in culture A, lactose permease was induced to a high level, during pretreatment with IPTG, which allowed the preferential uptake of lactose.
(4) in culture A, IPTG activated a receptor which bound lactose more efficiently, thereby triggering a signal.
7. 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?
(1) bax
(2) bcl-2
(3) p53
(4) caspase-3
8. 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):
A) CCA CC AUG G
B) CCG CC AUG G
C) CCG CC AUG C
D) AAC GG AUG A
Which of the following sequence sets related to the above postu1ations is correct?
(1) A and B
(2) A and C
(3) C and D
(4) B and D
9. 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:
A) eIF-4G and PABP promote this process through 5'-3' interaction of mRNA.
B) ribosomes are less active in recognizing circular mRNA.
C) PABP and eIF-4A promote this process.
D) ribosomes can reinitiate translation without being disassembled.
Which of the following is correct?
(1) A and D
(2) B and D
(3) A and C
(4) B and C
10. 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.
A) Both siRNAs and miRNAs are processed by cytoplasmic endonuclease Dicer.
B) 'Drosha' is needed for processing miRNAs and precursor siRNAs.
C) Both siRNAs and miRNAs show association with Argonaute protein.
D) Both the processing pathways involve RISe complex.
Which of the following combinations is NOT correct?
(1) A and C
(2) C and D
(3) A and B
(4) D and A
11. Glucose is mobilized in muscle when epinephrine activates Gαs. In an experiment in which muscle cells were stimulated with epinephrine, glucose mobilization was observed even after withdrawal of epinephrine. This could be
(1) due to the presence of a cAMP phosphodiesterase inhibitor.
(2) very low rates of cyclic AMP formation.
(3) due to the presence of a cAMP phosphodiesterase activator.
(4) due to the absence of protein kinase A.
12. In eukaryotic chromatin, 30 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.
A) The gene in (A) is repressed.
B) The gene in (B) is repressed.
C) The gene in (A) is active.
D) The gene in (B) is active.
Which of the following sets is correct?
(1)A and D
(2) A and B
(3) Band D
(4) C and D
13. 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 one of the following combinations of the above statement is true?
(1) A and D
(2) A and C
(3) B and C
(4) B and D
14. During early cleavage of Caenorabditis 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:
(1) P1 cell would develop autonomously while the AB would show conditional development.
(2) P1 cells would show conditional development while AB would show autonomous development.
(3) Both would show autonomous specification and result in mosaic development.
(4) Both would show conditional specification and result in regulative development.
15. 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
(1) neotype for A only.
(2) neotype for A and lectotype for B.
(3) neotypes for both A and B.
(4) lectotype for both A and B.
16. According to MacArthur and Wilson's equilibrium theory, which of the following is true?
(1) Larger islands and islands closer to continent are expected to have more species than smaller and isolated islands.
(2) Smaller islands and islands far from the continent are expected to have more species than larger and isolated islands.
(3) Smaller islands and islands closer to the continent are expected to have more species than far away smaller and isolated islands.
(4) More species are expected on all islands irrespective of their size and distance from the continent.
17. 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?
(1) It depends on how one defines niche.
(2) There are in nature many instances of continued coexistence of closely related species.
(3) The principle is universally true.
(4) It does not predict the outcome where, both the species are equally strong competitors.
18. 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),
(1)P and C are controlled by B, and Z is controlled by T
(2) P, Z and C are all controlled by T
(3) P is controlled by B, Z is controlled by T and C is controlled by B
(4) P is controlled by T, Z is controlled by B and C is controlled by T
19. What will be the approximate effective population size in a panmictic population of 240 with 200 females and 40 polygamous males?
(1) 160
(2) 133
(3) 63
(4) 67
20. 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).whichmodulates the phase and period of B. However, upon withdrawal of 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 causes entrainment of B.
D) B is a conditioned to E.
The correct answer is
(1) A and C
(2) B and D
(3) B only
(4) D only
21. What is the minimum number of NTPs required for the formation of one peptide bond during protein synthesis?
(1) One
(2) Two
(3) Four
(4) Six
22. 'Imperfect fungi' is a group represented by fungal species which have
(1) simple mycelia.
(2) no known mechanisms of sexual reproduction.
(3) unkown phylogenetic relationship.
(4) lost its survival mechanism against harsh environments.
23. The photoreceptor commonly involved In light entrainment of the biological clock in flies, moulds and plants is
(1) phytochrome.
(2) rhodopsin
(3) carotenoid.
(4) Cryptochrome.
24. The free energy âG of a dissolved solute
(1) Increases with solute concentration.
(2) decreases with solute concentration
(3) is independent of solute concentration.
(4) depends only on temperature.
25. Which of the following is not a characteristic of phylum Chordata?
(1)Pharyngeal slits
(2) Amniotic egg
(3) Post anal tail
(4) Notochord
