CSIR NET June 2012 Part B solved Question

1.     Which of the following is followed for the formation of terpenes

a) Mevalonic and MEP pathway b. Malonic and MEP pathway c)Shikimic and mevalonic pathway
d).Shikimic and Malonic pathway
Ans.   a

Expln:- There are three kinds of secondary metabolites in plants namely terpenes or isoprenoid compounds, alkaloids and phenolics (flavonoids and non-flavonoids.

Isopentenyl pyrophosphate (IPP) is the fundamental unit in the biosynthesis of terpene or isoprenoid. Mevalonic acid pathway is an important pathway present in all higher eukaryotes and many bacteria for the production of IPP.

In contrast to the classical mevalonic acid pathway of IPP biosynthesis, there is a non-mevalonate pathway seen in the plastids of plant, protozoa and prokaryotes. It is is known as methyl erythritol phosphate pathway (MEP pathway). In the initial step of MEP pathway,deoxy xylulose-5-phosphate (DOXP) is formed by condensation of pyruvic acid and glyceraldehyde 3-phosphate. DOXP is reduced to methyl erythritol phosphate (MEP). MEP, through several steps, IPP is formed, which is used for the synthesis of terpenes. MEP pathway is also known as DOXP pathway.

2.     Which of the following is not a phytoremediation method ?

a. Phytodegradation b. Chelated accumulation c.Phytovolatilisation d.Phytomining

Ans.   d

Expln:- Phytodegradation, phytovolatilisation, chelated accumulation etc. are different phytoremediation methods (details see instant notes). In chelated accumulation, synthetic metal chelate such as ethylene diamine tetraacetic acid (EDTA)is applied to soil enhancing metal accumulation by plants.

Phytomining and phytoremediation are essentially the same thing, but with different goals. While phytoremediation has an environmental goal, phytomining has an economic goal, but the principle is the same. Phytomining offers the possibility of exploiting ores or mineralized soils that are uneconomic by conventional mining methods. Our current research focuses on developing our Phytoremediation Decision Support System to reveal where phytomining is economically feasible and optimize phytomining management practices.

3.     The major interaction in B-DNA which stabilizes it is

a. Van der Waals interactions 2 b. hydrogen bond c.ionic bond d.hydrophobic interactions

Ans.   b

Expln:- The double helix is stabilized by two forces: hydrogen bonds between nucleotides and base-staking interactions among the aromatic nucleobases. In chemistry, Pi stacking refers to attractive, noncovalent interactions between aromatic rings. These interactions are important in base stacking of DNA molecules, protein folding, template-directed synthesis etc.
4.     In which part of the membrane phosphotidylserine is localized ?

a. Inner leaflet but flip flops to outer leaflet b. Outer leaflet but flip flops to inner leaflet c.I ntercalated between the membrane lipids d.both inner and outer leaflets

Ans.   a

Expln:- The two layers of lipids in the bilayer are referred to as the inner and outer leaflets. In biological membranes the individual lipid species are asymmetrically distributed between the two leaflets. For example, in the plasma membrane of erythrocytes, sphingomyelin and phosphatidylcholine are preferentially located in the outer leaflet, whereas phosphatidylethanolamine and phosphatidylserine are mainly in the inner leaflet.
5.     Which chronological order is correct ?

i) Prokaryotic cell ii) Eukaryotic cell iii)Natural selection iv)Organic molecule v)Self replicating molecule

a. iv, v, i, ii, iii b. iv, v, iii, i, ii c.iv, v, i, iii, ii d.i, v, ii, iv, iii

Ans.   c
6.     Which of the following is used as biocontrol agent ?

a. Safola b. Trichoderma c.Fusarium d.Rhizobium

Ans.   b

Expln:- Trochoderma viridae is a fungus and a biofungicide. It is used for suppression of various disease caused by fungal pathogens.
7.     Which of the following is the stable vector to insert eukaryotic DNA of 140 kb size ?

a. BAC b. YAC c.Cosmid d.Plasmid

Ans.   a

Expln:- YACs are the most sophisticated yeast vectors and represent the largest capacity vectors available. It is used to clone DNA fragment larger than 100 kb and upto 3000 kb. BAC vectors can accommodate DNA inserts upto 300 kb. Hence both BAC and YAC may be used to insert 140 kb size. However, YACs are significantly less stable than BAC. Hence the stable vector to insert DNA of 140 kb is BAC vector.
8.     Spore formation in bacteria is due to

a. Nutritional deficiency b. pH changes c.heat stress d.cold stress

Ans.   a
9.     Mycobacterium tuberculosis can infect which of the following cells of immune system?

a. T cells b. macrophages c.B cells d.neutrophils

Ans.   b
10.     Which of the following cell has CD19 as the cell surface marker ?

a. T cell b. NK cell c.B cell d.Macrophages

Ans.   c

Expln:- CD19 is a protein encoded by the CD19 gene. It is found on the surface of B-cells.
11.     Choose the correct matching

A Gunnera    1 Frankia

BSoyabean 2Nostoc

CAzolla        3Bradyrhizobium

DCasurina 4Anabena

a. A-2, B-1, C-4, D-3 b. A-1, B-4, C-2, D-3 c.A-2, B-3, C-4, D-1 d.A-3, B-1, C-3, D-4