Which of these has been controlled in an attempt to reduce the depletion of ozone in earth’s atmosphere?
methods of filtering gasoline
use of chlorofluorocarbons (cfcs)
use of mercury (hg) compounds
methods of radioactive waste storage

The term used to describe a disease-causing microorganism isa. virus.b. infection.c. pathogen.d. microbe.e. bacterium.

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass