Which of the following refers to the inner hollow cavity of a blastula? 

Global warming is caused by an increase in which of the following?

How does the Helicobacter pylori spread?

A controlled experiment is one that must

Which of the following is not one of the four basic characteristics of chordates? 

Regulation of genes can happen during?

What does a food web show that a food chain does not?  

What forms from the notochord?

There is a species of ant that lives on Acacia trees. Over time, the ants have evolved behaviors that protect the tree from being eaten by herbivores. The Acacia tree has evolved hollow thorns in which the ants can live and build nests. This is an example of

Which of the following is not a germ layer?