The correct answer is "B. 1 and 2 only."
Viruses contain either DNA or RNA as their genetic material, but not both. They use host cells to synthesize virus proteins and replicate their genetic material. Viruses do not have a protective coat of peptidoglycan, which is a type of polymer that forms the cell wall in bacteria.
Therefore, the only two statements that are correct are 1 and 2: "They contain DNA or RNA. They use host cells to synthesize virus proteins."
A. "1, 2, and 3" are incorrect because statement 3, "They can have a protective coat of peptidoglycan," is false. Peptidoglycan is a component of bacterial cell walls, not viral coatings.
C. "1 and 3 only" are incorrect because statement 3, "They can have a protective coat of peptidoglycan," is false. Peptidoglycan is a component of bacterial cell walls, not viral coatings.
D. "2 and 3 only" are incorrect because statement 3, "They can have a protective coat of peptidoglycan," is false. Peptidoglycan is a component of bacterial cell walls, not viral coatings.
The correct answer is D. Sucrose.
Benedict's solution is used to test for the presence of reducing sugars, which are sugars that can reduce copper ions in Benedict's reagent to form a red-colored precipitate. If a blue solution is obtained after the test, it indicates that a non-reducing sugar is present, such as sucrose. Glucose, fructose, and maltose are all reducing sugars, so they would produce a red color if they were present in the sample.
Therefore, the presence of a blue solution after the Benedict's test indicates that sucrose, a non-reducing sugar, is likely to be present in the sample.
The other options, A. Glucose, B. Fructose, and C. Maltose are incorrect because they are reducing sugars and would produce a red color if present in the sample after Benedict's test. Benedict's test is used to detect reducing sugars, which can reduce copper ions in Benedict's reagent to form a red-colored precipitate.
If a blue solution is obtained after the test, it indicates that a non-reducing sugar is present, such as sucrose, and not a reducing sugar such as glucose, fructose, or maltose. Reducing sugars will reduce the copper ions and produce a red color, while non-reducing sugars like sucrose will not reduce the ions and the solution will remain blue.
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