To separate genomic DNA fragments by size, which of these laboratory methods is most useful?
Titration.
Electrophoresis.
Filtration.
Spectrophotometry.
The Correct Answer is B
Electrophoresis is a technique that uses an electric field to separate charged molecules, such as DNA fragments, based on their size and charge.
Choice A is not correct because titration is a laboratory method used to determine the concentration of a solution.
Choice C is not correct because filtration is a laboratory method used to separate solids from liquids.
Choice D is not correct because spectrophotometry is a laboratory method used to measure the absorbance of light by a solution.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV.
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
Correct Answer is C
Explanation
The two major parts of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
The CNS comprises the brain and spinal cord and acts as the integration and command centre of the body.
The PNS represents the conduit between the CNS and the body and is further subdivided into the somatic nervous system (SNS) and the autonomic nervous system (ANS).
Choice A is incorrect because it only mentions two subdivisions of the PNS: the autonomic nervous system (ANS) and the somatic nervous system (SNS).
Choice B is incorrect because it only mentions one major part of the nervous system, the PNS, and one subdivision of it, the SNS.
Choice D is incorrect because it only mentions one major part of the nervous system, the CNS, and one subdivision of the PNS, the ANS.
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