What is required for exponential growth to occur in a population?

What do animals wth echolocation have in common other than echolocation

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

Check all that apply diatoms are marine algae that have a shell made of silica, what are some of the uses of the silica shell after the diatoms die? 1.the shells make up the diatomaceous earth used in filters 2.it can be used as an ingredient in abrasives 3.they are used in food products 4.the shells can be used in some insulating materials