Refer to the graph below, which shows the amount of carbon present as starch, sucrose, and hexose sugars at various times over a 24-hour period in the chloroplasts of leaf cells from a living green plant.Dawn marks the zero time point, and dusk marks the 14-hour time point. These data provide evidence in support of which statement about chloroplasts?
A) The plant uses the carbohydrates produced in chloroplasts to make amino acids, lipids, and the building blocks of nucleic acids.
B) Chloroplasts are found in organisms called autotrophs that are able to carry out photosynthesis; chloroplasts are not found in organisms called heterotrophs that do not carry out photosynthesis.
C) Sugars accumulate in the chloroplasts as the result of photosynthesis and are stored in polysaccharide form until needed during the night, when photosynthesis stops.
D) Photophosphorylation occurs in the chloroplast, where electron transport is coupled to proton transport across a membrane.
E) The thylakoid membranes of a chloroplast contain light-harvesting complexes and electron transport proteins, while the stroma contains Calvin cycle enzymes.

Question

Refer to the graph below, which shows the amount of carbon present as starch, sucrose, and hexose sugars at various times over a 24-hour period in the chloroplasts of leaf cells from a living green plant.Dawn marks the zero time point, and dusk marks the 14-hour time point.  These data provide evidence in support of which statement about chloroplasts?
A) The plant uses the carbohydrates produced in chloroplasts to make amino acids, lipids, and the building blocks of nucleic acids. 
B) Chloroplasts are found in organisms called autotrophs that are able to carry out photosynthesis; chloroplasts are not found in organisms called heterotrophs that do not carry out photosynthesis. 
C) Sugars accumulate in the chloroplasts as the result of photosynthesis and are stored in polysaccharide form until needed during the night, when photosynthesis stops. 
D) Photophosphorylation occurs in the chloroplast, where electron transport is coupled to proton transport across a membrane. 
E) The thylakoid membranes of a chloroplast contain light-harvesting complexes and electron transport proteins, while the stroma contains Calvin cycle enzymes.

Quizplus · Accepted Answer

The graph shows that starch, sucrose, and hexose sugars accumulate in the chloroplasts during the day (between dawn and dusk) and then decrease during the night. This suggests that these sugars are being stored in the chloroplasts during the day, likely as a result of photosynthesis, and are being used during the night when photosynthesis is not occurring. This supports choice C, which states that sugars accumulate in chloroplasts as a storage strategy. The other choices are not supported by the data presented in the graph.

Refer to the Graph Below, Which Shows the Amount of Carbon