Chloroplasts capture light energy from the sun to produce the free energy stored in ATP and NADPH through a process called photosynthesis. Chloroplasts are one of the many unique organelles in the body, and are generally considered to have originated as endosymbiotic cyanobacteria.
Primary succession occurs at places where there was no vegetation or life before, usually places such as lava or places where glaciers were. Secondary occurs at places that have already previously been colonized, but the habitat was somehow disturbed or damaged.
A bacteria is a prokaryotic microorganism that can either be beneficial, or harmful to the body. A virus is acellular, and has no cellular structure, and needs a living host to survive; it causes illness in the host, which causes an immune response. Bacteria are alive and can be treated with an antibiotic if it is harmful to the body. Since viruses are considered nonliving, the virus itself cannot be eliminated, but the symptoms can be treated. Another thing a virus can do that a bacteria can't is genetically program itself into the cells, which means that if you get it once, the symptoms can show up throughout the course of the human's life.