Stem cells are what allow planaria to grow and regenerate as the stem cells can change into any of the cells that make up the planaria.
Human Immunodeficiency Virus causes HIV
Varicella Zoster Virus causes chicken pox
Volcanic eruptions spew alot of carbon dioxide and sulphur dioxide into the atmosphere. These gases when mixed with rain and run into oceans increase their pH. Additionally, these gases are greenhouse gases that increases atmospheric temperatures and consequently those of the seas and oceans.
Low pH and high temperatures kill marine life.
Variation means difference in genetic makeup between individuals within a specie.
Melanin provides pigmentation to the skin and it also provides UV ray protection (which is its role in the epidermis).
