Answer:
You have external defense systems, which include your skin, tears, mucus, saliva, stomach acid, cilia (small hairs) and helpful bacteria. The skin, nails and hair form the integumentary system, which stops dirt and pathogens from entering the body.
Answer:
Either the cell wall or the cell membrane
Explanation:
For an animal to be extinct none more of that specific species must exist on Earth. This makes it impossible for that species to come back to life.
Well the more that get cut down, the less oxygen we get, aswell as more carbon in the atmosphere because there is less trees to absorb it.
