What is the difference between biofilm and colony?

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

Plz ! cattle ranchers and dairy farmers rarely allow all of their animals to reproduce instead they practice selective breeding and only encourage the reproduction of animals with specific features. which of the following cows would a dairy farm most likely choose to reproduce? a. a cow that makes a lot of milk. b. a cow that can run quickly. c. a cow with a think, soft fur. d. a cow with large, strong hooves.

Crossing over is a method of (blank)?