Living things gain and use matter and energy. Like, "Red Bull gives you wings"?
have established that all living critters have several levels of
organization. Since you continually reorganize your impeccably kept
biology notebook as if you were a squirrel hopped up on caffeine
, we know you have no doubt that maintaining
organization requires energy—lots and lots of energy.
Think of all the
calendars, day planners, and lists that you have made in your lifetime
(or haven't made, if you aren't the planning type). Organization is
hard! Cells acquire matter and energy to not only maintain their
structures and functions, but also to grow and reproduce. Bow chicka wow
wow. The matter and energy acquired by a living organism are used in
chemical reactions, and the sum of all these chemical reactions in one
living organism is referred to as its metabolism.
get their matter and energy from the environment. Depending on the type
of organism, matter in the form of nutrients can be "sipped" from air,
soil, water, and/or food. Energy, on the other hand, is created either
by photosynthesis or by extracting it from other living organisms. That
would explain why little ol' humans like us feel mighty sluggish after
going a few hours without eating.
Some living creatures—like plants and
many unicellular organisms—perform photosynthesis: they convert light
from the sun directly into usable energy. Other living things—like
fungi, non-photosynthetic unicellular organisms, and animals—eat other
living things. Not very neighborly, but hey, it’s a dog-eat-dog-food