In the case of monoclonal antibody production by hybridoma technology, myeloma cells used to lack the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) such that fused can only survive when selected on hypoxanthine-aminopterin-thymidine (HAT). What is the role of aminopterin in this medium?

• To be used as cell cycle inhibitor of myeloma cells

• To block the pathway for nucleotide synthesis

• To facilitate fusion of myeloid B cells and antibody-producing B cells

• To facilitate production of antibody-producing B cells

Which of the following atomic nuclei cannot be probed by nuclear magnetic resonance spectroscopy?

• ¹H

• ³¹P

• ¹⁸O

• ¹⁵N

Evolution of multi-gene family occurs by

• only gene duplication

• only unequal crossing over

• random mutations

• both duplication and unequal crossing over

The speciation in which a population splits into two geographically isolated populations experience dissimilar selective pressure and genetic drift is known as

• sympatric speciation

• parapatric speciation

• peripatric speciation

• allopatric speciation

t_1/2 of an irreversible first-order reaction, S → P is 1 hour. the time (in hours) required to reach 75% completion is

• 1.5

• 2.0

• 2.5

• 3.0

For developing transgenic mice, embryonic stem cells are engineered to express the transgene. These cells are selected by

• novobiocin

• neomycin

• tetracycline

• penicillin

Which of the following genes was engineered in the "Flavr Savr" transgenic tomato variety?

• 1-Amino cyclopropane-1-carboxylic acid synthase

• 1-Amino cyclopropane-1-carboxylic acid oxidase

• Expansin

• Polygalactouronase

Microbial leaching involves the process of dissolution of metals from ore breaking rocks using micro-organisms. Which one of the following bacteria helps in leaching copper from its ore?

• Acidithiobacillus ferroxidans

• Pseudomonas putida

• Deinococcus radiodurans

• Rhodopseudomonos capsulate

One aims to find out the role of a gene product in macrophages by using a transgenic mouse expressing the genes under a promoter. Which of the following is the most appropriate promoter?

• Actin promoter

• MHC Class II promoter

• Mac-1/ CD 11b promoter

• IL-2 promoter

The molar absorption coefficient of phenylalanine is 200 M^-1cm^-1 at257 nm. What concentration (g/L) of this amino acid will give an absorption of 1 in a cell of 0.5 cm path length at 257 nm?

• 3.30

• 0.33

• 1.65

• 0.17