High School Biology : Understanding Light Reactions

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Light Reactions

In the given chemical process, what does  represent?

Possible Answers:

Carbohydrate

Carbon hydroxide

Carbonated water

Chlorophyll

Correct answer:

Carbohydrate

Explanation:

Carbohydrates are formed from carbon chains with a single oxygen group (either an aldehyde or a ketone). Carbohydrates have the general empirical formula . This formula can be used to designate a nonspecific carbohydrate molecule.

The process described is the conversion of light energy to chemical energy through photosynthesis. Chlorophyll serves as a functional pigment in this process, but is not involved in the net reaction. Carbonated water is formed from dissolved carbon dioxide in water, and is actually a solution of the two compounds. Carbon hydroxide is a misnomer, and does not refer to a real compound.

Example Question #3 : Photosynthesis

During the light-dependent reaction, the electron in __________ is __________ before the electron in  _________.

Possible Answers:

photosystem I. . . removed. . . photosystem III

photosystem II. . . oxidized. . . photosystem III

photosystem I. . . excited. . . photosystem II

photosystem II. . . excited. . . photosystem I

Correct answer:

photosystem II. . . excited. . . photosystem I

Explanation:

Contrary to their assigned numbers, the electron in photosystem II is excited before the electron in photosystem I. Their numbers are a reflection of the order in which they were discovered. 

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