To separate genomic DNA fragments by size, which of these laboratory methods is most useful?

A. Titration

B. Electrophoresis

C. Filtration

D. Spectrophotometry

Answer Explanation:

Electrophoresis is the most useful laboratory method for separating genomic DNA fragments by size.

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.

Therefore, the Correct Answer is B.

Q #1: Which of the following is correct regarding the pH scale?

A. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4

B. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4

C. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4

D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4

Answer Explanation

The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.

A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.

Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.

Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.

Choice A.

A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.

Choice B.

A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.

Choice D.

A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.
Q #2: Which of the following best describes the result of using a catalyst in a chemical reaction?

A. The reaction is completed in a shorter amount of time

B. A more desirable product is often formed

C. A greater amount of heat energy is released by the reaction

D. The yield of product is increased

Answer Explanation

A catalyst is a substance that increases the rate of a chemical reaction without being consumed by the reaction.

As a result, the reaction is completed in a shorter amount of time.

Choice B is not correct because using a catalyst does not necessarily result in the formation of a more desirable product.

Choice C is not correct because using a catalyst does not necessarily result in the release of a greater amount of heat energy by the reaction.

Choice D is not correct because using a catalyst does not necessarily increase the yield of product.
Q #3: Which of the following represents the complementary strand of a DNA sequence 3' TCGATCGCA 5'?

A. 3' AGCTAGCGT 5'

B. 5’ AGCTAGCGT 3’

C. 5' UCGAUCGCA 3'

D. 3' TCGUTCGCU 3'

Answer Explanation

In DNA, the nitrogenous bases adenine (A) and thymine (T) pair together, while cytosine (C) and guanine (G) pair together.

Therefore, the complementary strand of the given DNA sequence 3' TCGATCGCA 5' would have the complementary nitrogenous bases as:

5’ AGCTAGCGT 3’

NOTE: The 5’ to 3’ direction of the complementary strand is opposite to that of the given strand.

Choice A.

3’ AGCTAGCGT 5’ is not correct because it is not complementary to the given strand.

Choice C.

5’ UCGAUCGCA 3’ is not correct because it contains uracil (U), which is a nitrogenous base found in RNA, not DNA.

Choice D.

3’ TCGUTCGCU 3’ is not correct because it also contains uracil (U), which is a nitrogenous base found in RNA, not DNA.

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To separate genomic DNA fragments by size, which of these laboratory methods is most useful?

More Questions on TEAS 7 Science

Q #1: Which of the following is correct regarding the pH scale?

Answer Explanation

Q #2: Which of the following best describes the result of using a catalyst in a chemical reaction?

Answer Explanation

Q #3: Which of the following represents the complementary strand of a DNA sequence 3' TCGATCGCA 5'?

Answer Explanation

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To separate genomic DNA fragments by size, which of these laboratory methods is most useful?

More Questions on TEAS 7 Science

Q #1: Which of the following is correct regarding the pH scale?

Answer Explanation

Q #2: Which of the following best describes the result of using a catalyst in a chemical reaction?

Answer Explanation

Q #3: Which of the following represents the complementary strand of a DNA sequence 3&#39; TCGATCGCA 5&#39;?

Answer Explanation

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Q #3: Which of the following represents the complementary strand of a DNA sequence 3' TCGATCGCA 5'?