Which system does a human have, but not a flatworm? A. a digestive system

B. a reproductive system

C. a respiratory system with lungs

D. a nervous system

Drumb roll please...

Many animals cannot sweat to maintain a stable body temperature. what is one other way animals can cool down?

Approximately percent of the energy created by cell metabolism is used by the body to carry on its normal functions, such as respiration, digestion, reproduction, muscular movement, circulation, and cellular regrowth.

There are only about 250,000 known fossil species. true or false