Explanation:
550 million years ago....
Hope it helps
Answer:
protists is correct answer kids.so do it
7.5 too, its kinda of ratio, 1cm : 1Km to 7.5cm : x
x will be equal 7.5 km
Homeostasis is the ability to maintain a constant internal environment in response to environmental changes so organism must need it so they can be balanced internally in response to the environment .