CSIR Life Science Sample Questions (Part 5 of 10)

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  1. Pre-mRNAs are rapidly bound by snRNPs which carry out dual steps of RNA splicing, that removes the introns and joins the upstream and downstream exons. The following statements describe some facts related to this event.

    1. Almost all introns begin with GU and end with AG sequences an hence all the GU or AG sequences are spliced out of RNA.

    2. U2 RNA recognizes important sequences at the 3 acceptor end of the intron.

    3. The spliceosome uses ATP to carry out accurate removal of intron.

    4. An unusual linkage with 2 OH group of guanosine within the intron from a ‘Lariat’ structure.

    Which of the following combinations is correct?

    1. 1 2

    2. 2 3

    3. 3 4

    4. 4 1

  2. Assume a male sparrow (species X) is hatched and reared in isolation and allowed a critical imprinting period to hear the song of a male of another sparrow (species Y). Now after the isolation, what kind of behaviour will species X show?

    1. It will sing the song of species Y that it had heard in the critical period.

    2. It will sing the song of its own species X.

    3. It will not sing at all.

    4. It will sing a song not sung by either X or Y.

  3. A 1 meter tall object was placed 10 meter in front of a normal eye. The size of the image on the retina will be (consider distance between lens and retina = 1.7 cms)

    1. 0.17 mm

    2. 1.7 mm

    3. 3.4 mm

    4. 170 μm

  4. In human, protein coding genes are mainly organized as “exons” and “introns” There are intergenic regions that transcribe into various types of non-coding RNA (not translating into protein). Some introns may harbor also transcription units, which are

    1. always other protein coding genes.

    2. protein coding gene and RNA coding genes.

    3. always RNA coding genes.

    4. pseudo genes.

  5. A fixed smear of a bacterial culture is subjected to the following solutions in the order listed below and appeared red.

    1. Carbolfuchsin (heated)

    2. Acid-alcohol

    3. Methylene blue

    Bacteria stained by this method can be identified as

    1. Non-acid fast E. Coli

    2. Acid-fast Mycobacterium sp.

    3. Gram-positive E. Coli

    4. Gram-negative Mycobacterium sp.

  6. Survival of intracellular pathogens depends on the level of pro-inflammatory and anti-inflammatory cytokines in macrophages. In an experimental condition, Mycobacteria infected macrophages were treated with IL-6 or IL-12 for 4 hours at 37oC. Untreated cells were used as control. Cells were lysed and number of bacteria in each experimental set was counted by measuring colony forming unit (CFU): Which of the following observations is true?

    1. IL-12 treated cells contain more intracellular bacteria than control.

    2. IL-12 treated cells contain less intracellular bacteria than control

    3. IL-6 treated cells contain more intracellular bacteria than control

    4. IL-6 treated cells contain less intracellular bacteria than control

  7. The genetic relatedness (r) of an individual to his nephew is 0.25. The alleles that cause uncles to care for nephews will spread, according to Hamilton's Rule, only if the fitness benefit is

    1. equal to the cost of care

    2. more than the cost of care by 25%

    3. double the cost of care

    4. four times the cost of care

  8. Many cancers carry mutant p53 genes, while some cancers have normal p53 genes. p53 activates p21 (Waf1) which inhibits G1/S-Cdks and phosphorylation of the retinoblastoma protein (Rb). Cancers with normal p53 genes could

    1. express non-phosphorylatable form of Rb.

    2. express high levels of p53-deubiquitinases.

    3. express inactive forms of G1/S-cdks.

    4. express inactive forms of G1/S cyclins.

  9. For a normal heart, the time taken for atrial systole and diastole are As and Ad seconds, respectively, while the same for ventricular systole and diastole are Vs an Vd. Which one of the following equations is correct?

    1. As + Ad = Vs + Vd

    2. As + Ad < Vs + Vd

    3. As + Ad-Vs + Vd = 0

    4. As + Ad > Vs + Vd

  10. The following are statements about molecular markers in the context of plant breeding.

    1. Molecular markers can be used for elimination of undesirable traits.

    2. Molecular markers cannot be used for estimation of the genetic contribution of each individual parent in a segregating population.

    3. Molecular markers are used for mapping of QTLs, which is also possible by conventional techniques.

    4. Molecular markers can be used for selection of individuals from a population that are homozygous for the recurrent parent genotype at loci flanking the target locus.

    Which of the above statements are TRUE?

    1. 1 2

    2. 1 3

    3. 1 4

    4. 2 3