Which of the following allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell?
A. The phospholipids found on the envelope of the virus.
B. Reverse transcriptase, an enzyme encoded by the virus.
C. Receptor proteins located on the surface of the virus.
D. The protein that makes up the capsid of the virus.
Reverse transcriptase, an enzyme encoded by the virus.
Reverse transcriptase is a virus-specific enzyme that transcribes an RNA template to DNA1.
This allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell.
Choice A, The phospholipids found on the envelope of the virus, is not the correct answer because phospholipids are a major component of cell membranes and do not play a direct role in inserting viral DNA into the DNA of a host cell.
Choice C, Receptor proteins located on the surface of the virus, is not the correct answer because receptor proteins located on the surface of the virus play a role in attachment and fusion of HIV virons to host cells, but do not play a direct role in inserting viral DNA into the DNA of a host cell.
Choice D, The protein that makes up the capsid of the virus, is not the correct answer because capsid is the outer protein shell of a virus and does not play a direct role in inserting viral DNA into the DNA of a host cell.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
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Q #1: Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?
A. Conversion to carbon monoxide.
B. Diffusion down a concentration gradient.
C. Passive transport using carrier proteins.
D. Active transport using energy.
Answer Explanation
Diffusion down a concentration gradient causes most of the carbon dioxide from the blood to move into the alveoli.
The alveoli are tiny air sacs in the lungs where gas exchange occurs.
Carbon dioxide is a waste product of cellular respiration and is carried by the blood to the lungs to be exhaled.
In the lungs, carbon dioxide diffuses from the blood (where its concentration is high) into the alveoli (where its concentration is lower) down its concentration gradient.
Choice A is incorrect because carbon dioxide is not converted to carbon monoxide in the body.
Choice C is incorrect because passive transport using carrier proteins is not the primary mechanism by which carbon dioxide moves from the blood into the alveoli.
Choice D is incorrect because active transport using energy is not involved in the movement of carbon dioxide from the blood into the alveoli.
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Q #2: Which of the following vessels carries oxygenated blood?
A. Superior vena cava
B. Inferior vena cava.
C. Pulmonary artery
D. Pulmonary vein
Answer Explanation
The pulmonary veins are the vessels that carry oxygenated blood from the lungs to the left atrium of the heart.
Choice A is not correct because the superior vena cava carries deoxygenated blood from the upper body to the right atrium of the heart.
Choice B is not correct because the inferior vena cava carries deoxygenated blood from the lower body to the right atrium of the heart.
Choice C is not correct because the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.
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Q #3: Which of the following summarizes a change that takes place as a solid turns to a liquid?
A. Particles become less ordered.
B. Particles have a decrease in mobility.
C. Particles move closer together
D. Intermolecular forces between particles become stronger.
Answer Explanation
As a solid turns to a liquid, the particles become less ordered and more free to move around.
Choice B is not correct because particles have an increase in mobility as a solid turns to a liquid.
Choice C is not correct because particles move further apart as a solid turns to a liquid.
Choice D is not correct because intermolecular forces between particles become weaker as a solid turns to a liquid.
