which statement most accurately compares and contrasts the structures of dna and rna

ATI TEAS 7

ATI TEAS 7 Science Practice Test

1. Which statement most accurately compares and contrasts the structures of DNA and RNA?

A. Both DNA and RNA have 4 nucleotide bases. Three of the bases are the same, but the fourth base is thymine in DNA and uracil in RNA.
B. Both DNA and RNA have the same 4 nucleotide bases. However, the nucleotides bond differently in DNA compared to RNA.
C. Both DNA and RNA have different numbers of nucleotide bases. DNA is a double helix while RNA is a single strand.
D. Both DNA and RNA have a double helix structure. However, DNA contains 6 nucleotide bases and RNA contains 4 nucleotide bases.

Correct answer: A

Rationale: The correct answer is A because DNA and RNA both consist of 4 nucleotide bases, namely adenine, cytosine, and guanine, which are common in both. The key difference lies in the fourth base, which is thymine in DNA and uracil in RNA. This distinction is fundamental in understanding the structural variances between DNA and RNA. Choice B is incorrect as it incorrectly states that the nucleotides bond differently in DNA compared to RNA without specifying the crucial base differences. Choice C is inaccurate as it misrepresents the numbers of nucleotide bases in DNA and RNA, and incorrectly describes DNA as a double helix and RNA as a single strand, which is not related to the difference in bases. Choice D is incorrect as it inaccurately portrays DNA with 6 nucleotide bases and RNA with 4, which is not true; both DNA and RNA have 4 nucleotide bases, but with differences in one of the bases.

2. DNA has both a 'sense' and 'antisense' strand. What is true about the antisense strand?

A. It runs 5' to 3'.
B. It runs 3' to 5'.
C. It is used in replication.
D. It is the direction DNA is stored.

Correct answer: B

Rationale: The correct answer is B: 'It runs 3' to 5'. The antisense strand runs in the 3' to 5' direction, complementing the sense strand. Choice A is incorrect as the antisense strand runs in the opposite direction, which is 3' to 5'. Choice C is incorrect because the antisense strand is not directly involved in replication. Choice D is incorrect as the direction DNA is stored is not determined by the antisense strand.

3. What are polymers?

A. Large molecules formed by repeating units called monomers
B. Simple organic molecules with low boiling points
C. Highly reactive compounds used in industrial processes
D. Insoluble solids with no definite structure

Correct answer: A

Rationale: Polymers are large molecules formed by repeating units called monomers. These monomers link together to form long chains or networks, giving polymers their unique properties such as flexibility, strength, and durability. Choice B is incorrect because polymers are not simple organic molecules with low boiling points, but rather complex structures formed by polymerization. Choice C is incorrect as polymers are not necessarily highly reactive compounds, and they are not exclusively used in industrial processes. Choice D is incorrect because polymers can have varying solubilities and structures depending on their composition and properties.

4. What is the function of the pleurae?

A. To compartmentalize and lubricate the lungs
B. To facilitate the flow of air
C. To produce mucus
D. To serve as the passageway for air

Correct answer: A

Rationale: The pleurae play a crucial role in compartmentalizing and lubricating the lungs. The pleura is a double-layered membrane that surrounds the lungs and lines the chest cavity. This double-layered structure reduces friction between the lungs and the chest wall during breathing movements, allowing smooth expansion and contraction of the lungs. Options B, C, and D are incorrect. Option B, 'To facilitate the flow of air,' is incorrect because while the pleurae are involved in the respiratory process, their primary function is not to directly facilitate the flow of air. Option C, 'To produce mucus,' is incorrect as the production of mucus is not a primary function of the pleurae. Option D, 'To serve as the passageway for air,' is incorrect as the passageway for air refers to the air passages like the trachea and bronchi, not the pleurae. Therefore, option A is correct as it accurately describes the function of the pleurae.

5. How do hydrogen bonds in water affect its characteristics?

A. Hydrogen bonds are not polar enough to attract non-polar molecules.
B. Hydrogen bonds cause water to be less dense when it is a solid than when it is a liquid.
C. Hydrogen bonds cause water to have high surface tension, allowing some organisms to move across it.
D. Hydrogen bonds cause water to be a good solvent.

Correct answer: C

Rationale: Hydrogen bonds in water contribute to its high surface tension, enabling some organisms to move across the water's surface. This property is essential for certain insects and small animals that rely on surface tension to move or stay afloat on water. Choice A is incorrect because hydrogen bonds are polar and can attract polar and other charged molecules. Choice B is incorrect as hydrogen bonds make ice less dense than liquid water, which is a unique property. Choice D is incorrect as the ability of water to act as a good solvent is primarily due to its polarity, not just hydrogen bonding.