Aset of ideas that is proposed to explain something is a:

theory

tissue

system

statement

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

What is usually (but not always) related to the metabolic processes of living organisms in its organic form?

What if the yeast were extremely active and produced more than 100ml gas. would you know? why/why not