Competent Host - Class 12 Biology MCQ

This set of Class 12 Biology Multiple Choice Questions & Answers (MCQs) focuses on “Tools of Recombinant DNA Technology: Competent Host” for Schools.

1. The molecule which dissolves in water is called _______
a) hydrophilic molecule
b) hydrophobic molecule
c) soluble molecule
d) insoluble molecule
View Answer

Answer: a
Explanation: The molecule which dissolves in water is called hydrophilic molecules. They are polar in nature which helps them in dissolution in water. Being hydrophilic in nature DNA cannot pass through the cell membrane.

2. ______ is a hydrophilic molecule.
a) Lipid
b) DNA
c) Palmitic acid
d) Lipohilic
View Answer

Answer: b
Explanation: DNA is an example of a hydrophilic molecule. Hydrophilic molecules are water-loving and tend to dissolve in water easily. They carry a positive or negative charge.

3. Which divalent cations are usually used to make competent cells?
a) Carbon
b) Nitrogen
c) Copper
d) Calcium
View Answer

Answer: d
Explanation: The divalent cations of calcium are used to make cells competent. Calcium is used in the form of a salt of calcium chloride. It increases the efficiency of the bacterial membrane to allow the passage of foreign DNA.

4. The cells which have the ability to incorporate foreign DNA within them are called ______
a) water-loving
b) plasma cells
c) competent cells
d) hydrophobic
View Answer

Answer: c
Explanation: Some bacterial cells have the ability to incorporate foreign DNA within them. These cells are called competent cells. This leads to the alteration of the genetic material of the cell.

5. Competent cells can be prepared using ________
a) electrophoresis
b) chromatography
c) heat-shock treatment
d) pipetting
View Answer

Answer: c
Explanation: Heat-shock treatment is a method in which the vial is incubated in ice, then treated at temperature up to 50°C and again transferred on ice. It is usually used in transferring recombinant DNA within the host (bacterial cell).

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6. The method by which recombinant DNA is directly injected into the nucleus of an animal cell is called ________
a) heat-shock
b) micro-injection
c) transferring
d) insertional inactivation
View Answer

Answer: b
Explanation: The method by which recombinant DNA is directly injected into the nucleus of an animal cell is called micro-injection. A glass micropipette is used for injecting the material into cells.

7. Biolistics is also known as ______
a) micro-injection
b) micro-pipetting
c) insertional inactivation
d) gene gun
View Answer

Answer: d
Explanation: Biolistics is also known as a gene gun. It is a method in which cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA. It is mostly used for plant cells.

8. What temperature is suitable for heat-shock treatment?
a) 100°C
b) 0°C
c) 42°C
d) 95°C
View Answer

Answer: c
Explanation: 42°C-45°C is the ideal temperature for heat-shock treatment. Mostly calcium chloride is used in this. It is suitable for the transformation of bacterial cells such as E.coli.

9. Calcium is a ________ cation.
a) monovalent
b) trivalent
c) divalent
d) tetravalent
View Answer

Answer: c
Explanation: Calcium is a divalent cation. It has a valency of 2 and is written as Cu²⁺. Some other examples of divalent atoms are Zn²⁺, Mg²⁺, Co²⁺, etc.

10. Which metal microparticles are used in gene gun?
a) Aurum
b) Nitrogen
c) Magnesium
d) Cuprum
View Answer

Answer: a
Explanation: The microparticles of gold-coated with DNA are used in gene gun technique. Aurum is a Latin word for gold. Other metal used for this technique is tungsten.

11. Which method uses a ‘disarmed pathogen’ vector?
a) Transformation
b) Biolistics
c) Insertional inactivation
d) Sequencing
View Answer

Answer: b
Explanation: Biolistics or gene gun is the method that uses a ‘disarmed pathogen’ vector. A pathogen from which virulence or disease-causing genes are removed is known as a disarmed pathogen. It is a process in which DNA is transferred into a host without any risk of infection.

Sanfoundry Global Education & Learning Series – Biology – Class 12.

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