Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Question: Four electron groups orient themselves into what shape that has four faces? Answer: tetrahedron
Four electron groups orient themselves in the shape of a tetrahedron.

Question: How many types of major tissues do modern plants have? Answer: three
A tissue is a group of specialized cells of the same kind that perform the same function. Modern plants have three major types of tissues. They're called dermal, ground, and vascular tissues.

Question: Particles of different densities exert different amounts of what? Answer: pressure
Christopher Auyeung. Particles of different densities exert different amounts of pressure . CC BY-NC 3.0.