Which of the following allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host T-cell after the AIDS virus enters the cell?
A. Reverse transcriptase, an enzyme encoded by the virus.
B. Receptor proteins located on the surface of the virus.
C. The phospholipids found on the envelope of the virus.
D. The protein that makes up the capsid of the virus.
Reverse transcriptase, an enzyme encoded by the virus. This enzyme can convert the viral RNA into DNA, which can then integrate into the host cell's genome and hijack its machinery to produce more viruses. The other options are not relevant to this process. Receptor proteins are involved in binding the virus to the cell membrane, but they do not insert viral DNA into the cell. The phospholipids and the protein capsid are structural components of the virus, but they do not have any enzymatic activity.
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?
A. Osmosis
B. Diffusion
C. Facilitated diffusion
D. Active transport
Answer Explanation
One of the ways that cells regulate their water balance is by adjusting to different solute concentrations in their environment. When a cell is placed in a solution that has a higher concentration of solutes than the cell itself, the solution is called hypertonic. In this case, water will tend to move out of the cell through special channels called aquaporins, which are embedded in the plasma membrane. This movement of water across a selectively permeable membrane is a type of passive transport called osmosis. Osmosis does not require any energy input from the cell, unlike other forms of transport such as diffusion, facilitated diffusion, or active transport.
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Q #2: Which of the following statements best describes the function of erythropoietin in the human body?
A. It aids in lowering oxygen levels in the blood.
B. It aids in raising levels of clotting factors in the blood.
C. It aids in raising hemoglobin levels in the blood.
D. It aids in lowering CO2 levels in the blood.
Answer Explanation
Erythropoietin is a hormone that is produced by the kidneys and stimulates the production of red blood cells in the bone marrow. Red blood cells contain hemoglobin, a protein that binds to oxygen and transports it to the tissues. Therefore, erythropoietin helps to maintain adequate oxygen levels in the blood and prevent anemia.
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Q #3: Which of the following is a mass within the ovary that secretes hormones to maintain the uterine lining during pregnancy?
A. Oviduct
B. Corpus luteum
C. Oocyte
D. Umbilical cord
Answer Explanation
Corpus luteum. The corpus luteum is a temporary structure that forms from the ruptured follicle after ovulation. It produces progesterone, which is a hormone that prepares the endometrium (the inner lining of the uterus) for implantation of a fertilized egg. If pregnancy occurs, the corpus luteum continues to secrete progesterone until the placenta takes over.
