Answer:
They need backups.
Explanation:
If the organism only has one food source they will use up that resource and eventually the organism will deplete due to lack of food.
Traits such as skin color and height are variable throughout the human population because these traits are controlled by more than one cell. The cells don't perform at the same rate and don't produce the same biomolecules. Therefore, the maximum height of a person is not achieved which results to variations.
Her condition is referred to as endometriosis. The endometriosis is a repeatedly sore condition in which soft tissue that usually lines in the inner part of the uterus which is the endometrium develops at the outer part of the uterus and most usually includes the fallopian tubes, the ovaries and the soft tissue in inside layer of the pelvis.
Http://www.indiana.edu/~geol105/images/gaia_chapter_3/wegener.htm
read this
