NEET Biology Biotechnology MCQs Set 02

Answer: (c) making transient pores in the cell membrane to introduce gene constructs

Explanation:
1. A brief electric pulse opens temporary pores in the membrane so that DNA can enter the cell.
2. So the correct choice is option (c).

Teacher's Note:
1. Vectorless transfer.
2. Pores reseal.

Answer: (c) HaeIII

Explanation:
1. HaeIII cuts GG|CC symmetrically, leaving blunt ends. BamHI and EcoRI leave sticky (staggered) ends.
2. So the correct choice is option (c).

Teacher's Note:
1. Blunt: cut in the middle.
2. Sticky: staggered cut.

Answer: (d) protect its DNA from its own restriction enzymes

Explanation:
1. Methylation of the recognition site stops the bacterium's own restriction enzyme from cutting its DNA.
2. So the correct choice is option (d).

Teacher's Note:
1. Methylase partners restriction enzyme.
2. Self vs non-self.

Answer: (b) joins DNA fragments

Explanation:
1. Ligase forms phosphodiester bonds, sealing nicks and joining fragments.
2. So the correct choice is option (b).

Teacher's Note:
1. Molecular glue.
2. Works with sticky ends.

Answer: (b) retrovirus

Explanation:
1. Disarmed retroviruses can integrate genes into the genome of animal cells.
2. So the correct choice is option (b).

Teacher's Note:
1. Used in gene therapy.
2. Integrates DNA.

Answer: (a) denaturation, annealing, extension

Explanation:
1. Heat separates strands, primers anneal, and Taq polymerase extends them.
2. So the correct choice is option (a).

Teacher's Note:
1. D-A-E.
2. Repeated 30 times.

Answer: (b) DNA polymerases

Explanation:
1. They are DNA polymerases that withstand the heat of PCR.
2. So the correct choice is option (b).

Teacher's Note:
1. Thermus aquaticus: Taq.
2. Pyrococcus furiosus: Pfu.

Answer: (c) 1972

Explanation:
1. In 1972 Stanley Cohen and Herbert Boyer made the first recombinant DNA using a restriction enzyme and ligase.
2. So the correct choice is option (c).

Teacher's Note:
1. 1972 landmark.
2. Plasmid and antibiotic resistance gene.

Answer: (b) GAATTC

Explanation:
1. EcoRI recognises the palindrome GAATTC and cuts between G and A on each strand.
2. So the correct choice is option (b).

Teacher's Note:
1. Palindrome: reads same 5' to 3' on both strands.
2. Gives sticky ends.

Answer: (d) an origin of replication (ori)

Explanation:
1. Without ori the vector cannot replicate in the host, so the insert would not be copied.
2. So the correct choice is option (d).

Teacher's Note:
1. Ori controls copy number.
2. Others are desirable.

Answer: (b) DNA ligase

Explanation:
1. Complementary sticky ends hold fragments together by base pairing, so ligase can seal them.
2. So the correct choice is option (b).

Teacher's Note:
1. Sticky ends anneal.
2. Ligase forms the bond.

Answer: (b) recombinants

Explanation:
1. Insertional inactivation tells recombinants (which lose the resistance) from non-recombinants.
2. So the correct choice is option (b).

Teacher's Note:
1. Insert breaks the marker gene.
2. Replica plating.

Answer: (a) strain

Explanation:
1. E = Escherichia (genus), co = coli (species), R = strain RY13, I = order of discovery.
2. So the correct choice is option (a).

Teacher's Note:
1. Name decoding.
2. Roman numeral: order.

Answer: (c) beta-galactosidase

Explanation:
1. Insertion of DNA into lacZ destroys beta-galactosidase, so recombinant colonies stay colourless (white) and non-recombinant ones are blue.
2. So the correct choice is option (c).

Teacher's Note:
1. Blue-white screening.
2. Chromogenic substrate.

Answer: (b) colourless colonies

Explanation:
1. Recombinants lack functional beta-galactosidase and cannot make the blue product.
2. So the correct choice is option (b).

Teacher's Note:
1. Non-recombinants are blue.
2. Insert in lacZ.

Answer: (c) RNA primer

Explanation:
1. PCR uses synthetic DNA primers, not RNA primers.
2. So the correct choice is option (c).

Teacher's Note:
1. Needs dNTPs, buffer.
2. Taq adds nucleotides.

Answer: (c) double-stranded DNA

Explanation:
1. Restriction endonucleases recognise palindromic sites in double-stranded DNA.
2. So the correct choice is option (c).

Teacher's Note:
1. Two strands cut.
2. Not RNA.

Answer: (c) a plasmid used to transfer DNA into a living cell

Explanation:
1. A vector carries and replicates the gene of interest in the host.
2. So the correct choice is option (c).

Teacher's Note:
1. Plasmid or phage.
2. Needs ori.

Answer: (b) a modified (engineered) bacterial plasmid

Explanation:
1. pBR322 was built from natural plasmids and has amp and tet resistance genes and unique restriction sites.
2. So the correct choice is option (b).

Teacher's Note:
1. p = plasmid, BR = Bolivar and Rodriguez.
2. 322 = number.

Answer: (a) bollworms

Explanation:
1. These Cry proteins kill cotton bollworms; cryIAb controls corn borer.
2. So the correct choice is option (a).

Teacher's Note:
1. Bt cotton.
2. Cry proteins are specific.

Answer: (a) vitamin A

Explanation:
1. It makes beta-carotene (provitamin A) in the grain.
2. So the correct choice is option (a).

Teacher's Note:
1. Helps prevent night blindness.
2. Transgenes from daffodil and bacteria.

Answer: (b) C-peptide is removed

Explanation:
1. Human proinsulin has A, B and C peptides; removing C leaves chains A and B joined by disulphide bonds.
2. So the correct choice is option (b).

Teacher's Note:
1. Mature insulin: A and B chains.
2. Humulin: made in E. coli.

Answer: (d) Pseudomonas putida

Explanation:
1. Anand Chakrabarty's 'superbug' Pseudomonas putida degrades hydrocarbons.
2. So the correct choice is option (d).

Teacher's Note:
1. Bioremediation.
2. Multiple plasmids combined.

Answer: (c) tobacco

Explanation:
1. Transgenic tobacco, made in 1983, was the first.
2. So the correct choice is option (c).

Teacher's Note:
1. Flavr Savr: first GM food.
2. Tobacco is a model plant.

Answer: (d) all of these

Explanation:
1. Possible risks include toxins, allergies and spread of antibiotic resistance genes.
2. So the correct choice is option (d).

Teacher's Note:
1. GEAC regulates GM crops.
2. Biosafety assessment is needed.