Answer: atomic mass is the amount of protons and neutrons
Explanation:
Answer: 3.friction
Explanation: friction is a force of resistance acting between objects in contact and tending to dampen their motion
excretory system: removes waste from blood.
respiratory system: obtains oxygen so the energy in the nutrients can be extracted.
circulatory system: transports nutrients from small intestine to the othet tissues.
nervous system: regulates and controls digestive functioning.
( Am not completly sure, but i think this is the answer)
Introduced species can harm our planet because in some regions of the world we are not prepared for their type of species, which can all in all cause damage.
