5005 Blue Notes Practice Test

The main idea here is what cellular structures are unique to plant cells. Chloroplasts are the sites of photosynthesis, converting light energy into chemical energy inside plant cells. They contain chlorophyll, the pigment that gives plants their green color, and have the internal membranes where the light reactions and the Calvin cycle occur. Animal cells do not have chloroplasts, so they cannot perform photosynthesis themselves. That makes chloroplasts the distinguishing feature in this set of options.

Other structures listed—ribosomes, mitochondria, and cytoplasm—are found in both plant and animal cells. Ribosomes carry out protein synthesis, mitochondria generate most of the cell’s ATP, and cytoplasm is the jelly-like interior where many metabolic activities take place. Because these are common to both cell types, they don’t set plant cells apart in the way chloroplasts do.