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

A. Filtration

B. Spectrophotometry

C. Titration

D. Electrophoresis

Answer Explanation:

One of the most common techniques for separating DNA fragments by size is electrophoresis. Electrophoresis is a process that uses an electric field to move charged molecules through a porous gel matrix. The gel acts as a sieve, allowing smaller molecules to move faster and farther than larger ones. By applying a dye to the DNA samples and loading them into wells at one end of the gel, the DNA fragments can be visualized as bands after electrophoresis. The distance of each band from the well indicates the size of the corresponding DNA fragment.

Therefore, the Correct Answer is D.

Q #1: In a phase diagram, which of the following is the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously?

A. Triple point

B. Critical temperature

C. Absolute zero

D. Critical point

Answer Explanation

A phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. A phase diagram usually has pressure on the y-axis and temperature on the x-axis. As we move along the curves of the phase diagram, we can see how the state of the substance changes from solid to liquid to gas, or vice versa.
Q #2: In a certain plant, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. Which of the following is the expected proportion of phenotypes in the next generation?

A. 1 red, 3 white

B. 4 red, 0 white

C. 2 red, 2 white

D. 3 red, 1 white

Answer Explanation

The law of segregation states that each individual has two alleles for each trait, and these alleles separate during gamete formation. The allele that each gamete receives is random. Therefore, the probability of getting a certain genotype or phenotype depends on the Punnett square. In this case, the plant heterozygous for red flowers has the genotype Rr, where R is the dominant allele for red flowers and r is the recessive allele for white flowers. The plant with white flowers has the genotype rr. half of the offspring will have the genotype Rr and half will have the genotype rr. Since R is dominant over r, the offspring with Rr will have red flowers and the offspring with rr will have white flowers. Therefore, the expected proportion of phenotypes in the next generation is 2 red, 2 white.
Q #3: Which of the following properties of water explains its solvent abilities for certain substances?

A. Polarity of water molecules

B. High specific heat

C. High surface tension

D. Kinetic energy of liquid water molecules

Answer Explanation

Water is a versatile solvent because it can dissolve many different kinds of substances. The reason for this is the polarity of water molecules, which means that they have a slight positive charge on one end and a slight negative charge on the other. This allows water molecules to attract and surround ions or polar molecules of other substances, forming hydration shells that separate them from each other.

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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: In a phase diagram, which of the following is the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously?

Answer Explanation

Q #2: In a certain plant, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. Which of the following is the expected proportion of phenotypes in the next generation?

Answer Explanation

Q #3: Which of the following properties of water explains its solvent abilities for certain substances?

Answer Explanation

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