CSIR Life Science Sample Questions (Part 6 of 10)

  1. In ‘TaqMan’ assay for detection of base substitutions (DNA variant), probes (oligonucleotides) with fluorescent dyes at the 5-end and a quencher at 3-end are used. While the probe is intact, the proximity of the quencher reduces the fluorescence emitted by reporter dye. If the target sequences (wild type or the variant) are present, the probe anneals to the target sequence, down stream to one of the primers used for amplifying the DNA sequence flanking the position of the variants. For an assay two flanking PCR primers, two probes corresponding to the wild type and variant allele and labelled with two different reporter dyes and quencher were used. During extension the probe may be cleaved by the Taq-polymerase separating the reporter dye and the quencher. Three individuals were genotyped using this assay. Sample for individual I shows maximum fluorescence for the dye attached to the wild type probe, sample for individual II Shows maximum fluorescence for the dye attached to variant probe and sample for individual III exhibits equal fluorescence for both the dyes. Which of the following statement is correct?

    1. Individual I is homozygous for the variant allele.

    2. Individual II is homozygous for variant allele.

    3. Individual II is homozygous for wild type allele.

    4. Individual III is homozygous for wild type allele.

  2. A nerve impulse or action potential is generated from transient changes in the permeability of the axon membrane to Na + and K + ions. The depolarization of the membrane beyond the threshold level leads to Na + flowing into the cell and a change in membrane potential to a positive value. The K + channel then opens allowing K + to flow outwards ultimately restoring membrane potential to the resting value. The Na + and K + channels operate in opposite directions because

    1. there is an electrochemical gradient growth generated by proton transport

    2. there is a difference in Na + and K + concentrations on either side of the membrane

    3. Na + is a voltage-gated channel, whereas K + is ligand-gated

    4. Na + is dependent on ATP whereas K + is not

  3. When the prospective neurons from an early gastrula of a frog were transplanted into the prospective epidermis region, the donor cells differentiated into epidermis. However, when a similar experiment was done with the late gastrula of frog, the prospective neurons developed into neurons only. These observations could possibly be explained by the following phenomena.

    1. The early gastrula show conditional development whereas the late gastrula shows autonomous development.

    2. The early gastrula show autonomous development whereas the late gastrula shows conditional development.

    3. The prospective neurons from the early gastrula are only specified whereas those from the late gastrula are determined.

    4. The prospective neurons from the early gastrula are determined whereas those from the late gastrula are specified.

    Which of the conclusions drawn above are correct?

    1. 1 2

    2. 1 3

    3. 1 4

    4. 2 3

  4. The pH of blood of a healthy person is maintained at 7.40 ± 0.05. Assuming that the pH is maintained entirely by the bicarbonate buffer (of carbonic acid are 6.1 and 10.3, respectively), the molar ratio of [bicarbonate]/[carbonic acid] in the blood is

    1. 0.05

    2. 1

    3. 10

    4. 20

  5. Insulin and other growth factors stimulate a pathway involving a protein kinase mTOR, which in its turn augments protein synthesis. mTOR essentially modifies protein (s) which in their unmodified form act as inhibitors of protein synthesis. The following proteins are possible candidates.

    1. eEF-1

    2. eIF-4E-BP1

    3. eIF-4E

    4. PHAS-1

    Which of the following sets is correct?

    1. 1 2

    2. 2 4

    3. 1 3

    4. 2 3