A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light, whereas organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively,
A) mitochondria and chloroplasts.
B) chloroplasts and peroxisomes.
C) peroxisomes and chloroplasts.
D) chloroplasts and mitochondria.
E) mitochondria and peroxisomes.

Question

Quizplus · Accepted Answer

The organelles that can produce ATP in the light are likely chloroplasts, which are responsible for photosynthesis. The organelles that can produce ATP in the dark are likely mitochondria, which are responsible for cellular respiration. Therefore, the heavier fraction is likely to contain mitochondria and the lighter fraction is likely to contain chloroplasts.

A Biologist Ground Up Some Plant Leaf Cells and Then