What is the purpose of using PCR (polymerase chain reaction) in the laboratory?
To separate DNA fragments by size.
To amplify specific regions of DNA.
To sequence DNA fragments.
To analyze protein expression levels.
The Correct Answer is B
PCR (polymerase chain reaction) is a laboratory technique used to make many copies of a specific region of DNA.
The goal of PCR is to make enough of the target DNA region that it can be analyzed or used in some other way.
PCR has many research and practical applications, including DNA cloning, medical diagnostics, and forensic analysis of DNA.
Choice A is incorrect because PCR does not separate DNA fragments by size. Choice C is incorrect because PCR does not sequence DNA fragments.
Choice D is incorrect because PCR does not analyze protein expression levels.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Bacteria can perform photosynthesis while archaea cannot. Many types of bacteria can generate oxygen from sunlight through photosynthesis, while archaea cannot perform this process.
Choice A is incorrect because neither bacteria nor archaea have a true nucleus. Both are prokaryotic organisms.
Choice B is incorrect because archaea reproduce by fission, fragmentation, or budding, while bacteria can produce spores and divide sexually or asexually. Choice D is incorrect because archaeal and bacterial flagella are constructed differently.
Correct Answer is A
Explanation
Hydrogen bonding is an interaction involving a hydrogen atom located between a pair of other atoms having a high affinity for electrons.
One atom of the pair (the donor), generally a fluorine, nitrogen, or oxygen atom, is covalently bonded to a hydrogen atom, whose electrons it shares unequally; its high electron affinity causes the hydrogen to take on a slight positive charge.
The other atom of the pair (the acceptor), also typically F, N, or O, has an unshared electron pair, which gives it a slight negative charge.
Mainly through electrostatic attraction, the donor atom effectively shares its hydrogen with the acceptor atom, forming a bond.
Choice B) The repulsion between the positive and negative charges of two molecules is incorrect because hydrogen bonding involves attraction, not repulsion.
Choice C) The attraction between two nonpolar molecules is incorrect because hydrogen bonding involves polar molecules.
Choice D) The attraction between two ionic molecules is incorrect because hydrogen bonding involves polar molecules and not ionic molecules.
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