The exchange of nutrients and gases between a developing human embryo and its mother occurs between circulatory
fluids located within the
1) umbilical cord
3) manmary glands
2) placenta
4) yolk

List the advantages and disadavantages of the switch from persistent chlorinated hydrocarbon pesticides (such as ddt) to nonpersistent organophosphate pesicides. have the benefits of the switch outweighed the disadvantages? explain.

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water