Biochemistry : Other Light Reaction Concepts

Study concepts, example questions & explanations for Biochemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #2 : Light Reactions

In photosynthesis, if photosystem II absorbs 12 photons, how many molecules of  would be produced?

Possible Answers:

Correct answer:

Explanation:

Absorbing four photons by photosystem II creates one oxygen molecule, so absorbing 12 would produce 3 molecules of .

Example Question #4 : Carbohydrate Metabolism

During photosynthesis there is both a light phase and a dark phase. If the light phase were to continue unabated, but the dark phase came to a halt, which of the following is most likely to occur?

Possible Answers:

Decreased sensitivity of the chloroplast to incoming light

A proportional decrease in  

Increased sensitivity of the chloroplast to incoming light

Decrease in the level of 

An increase in the production of carbohydrates 

Correct answer:

Decrease in the level of 

Explanation:

During photosynthesis, the dark phase follows the light phase. The light phase produces  which, along with , is fed into the dark phase where it is consumed (becomes  and ). If the light phase continues working, but the dark phase does not, the  and  created during the light phase will not be consumed. Thus, there will be a decrease in the level of  and  (the correct answer). The relative proportion of  will actually increase.

Carbohydrate production is a result of the dark phase working properly, so their levels would decrease in this instance. The sensitivity of the chloroplast to light would not change.

Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: