A hormone often has effects only on certain cells. The reason the message of an "inappropriate" hormone is "ignored" by nontarget cells is that the nontarget cells .

A. have receptors for the hormone
B. have enzymes that break down the hormone
C. lack receptors for the hormone
D. lack the genes that the hormone is attempting to activate

How can you keep track of variables in a science experiment?

(drag each tile to the correct identify which questions can be answered by what can be answered by science or which cannot. -is it right or wrong to use genetic engineering to produce new food products? -what are the most common social settings that tend to produce accomplished artists? -if a new gene is added to the genome of a tomato species, will that species be more resistant to insects? -should humans use biotechnology to bring extinct organisms from the fossil record back to life? -do the types of organisms found in the fossil record appear in consistent sequences in different parts of the world? -are michelangelo's paintings more impressive than rembrandt's?

Is there any solid scientific evidence that humans have been cloned?