EVERYDAY SCIENCE

Detailed explanation-1: -Parasites are different from bacteria or viruses because their cells share many features with human cells including a defined nucleus. Parasites are usually larger than bacteria, although some environmentally resistant forms are nearly as small.

Detailed explanation-2: -Many disease-causing bacteria produce toxins-powerful chemicals that damage cells and make you ill. Other bacteria can directly invade and damage tissues.

Detailed explanation-3: -Pathogens are microorganisms that can cause disease. They can reproduce quickly in your body and give off poisons (toxins) that can cause infection. Harmful bacteria examples include: Streptococcus: Bacteria that cause strep throat. Staphylococcus: Bacteria that cause staph infections.

Detailed explanation-4: -Bacteria and viruses can live outside of the human body (for instance, on a countertop) sometimes for many hours or days. Parasites, however, require a living host in order to survive. Bacteria and parasites can usually be destroyed with antibiotics.