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
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.
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: Hikers who found a human body at high altitude in the Italian Alps thought the man had died recently, but tests indicated he was shot with an arrow more than 5,300 years ago. Which of the following would be the best reason for prolonged preservation of the body? .
A. The food that the person ate contained toxins that killed the bacteria that would have otherwise destroyed the body
B. The arrow wound caused blood to flow out of the body, which led the enzymes that would break down tissue to be cleared from the body
C. The body was frozen in the cold temperature of the Alps shortly after he died and remained frozen until it was found
D. The ultraviolet rays at such a high altitude caused all the body's molecules to be preserved.
Answer Explanation
The best reason for the prolonged preservation of the body is that it was frozen in the cold temperature of the Alps shortly after he died and remained frozen until it was found.
Freezing can preserve a body by slowing down or stopping the decomposition process.
Choice A is not correct because the food that the person ate would not have contained toxins that killed the bacteria that would have otherwise destroyed the body.
Choice B is not correct because the arrow wound would not have caused blood to flow out of the body in a way that would have cleared enzymes that break down tissue from the body.
Choice D is not correct because ultraviolet rays at high altitude would not have caused all of the body’s molecules to be preserved.
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Q #2: 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.
Answer Explanation
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.
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Q #3: 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.
