What is the difference in a salt crystal and a tree?

Question

They both grow. Which is living? How do you know? If you tested your hypothesis would there be a control? What would it be?

BIOLOGY HOMEWORK.

thanks so muchh.

Answer 1

Your biology textbook should have a list of criteria used in determining what is alive. These definitions have been refined over the years but remain basically the same as in the past. (Life should include things like it metabolizes incoming food and excretes waste. The list also should mention reproduction, for example.) A tree will meet those defining aspects of life while a salt crystal won't.

That doesn't mean that determining the "boundary" between living and non-living is not tricky at times.  Viruses, for example, have always been a curious question mark!