Convection currents occur: a. Only in liquids
b. When a dense substance is warmer than a less dense substance
c. In both liquids and gases
d. Weakly in solids

There are six elements that make up most of the human body. which of the following is not one of these six elements?

What mistake did john needham make that caused him to conclude that spontaneous generation for microorganisms occurred? a. he re-contaminated his boiled broth solutions. b. he destroyed the vital force in the solutions. c. he did not boil his broth solutions, only warmed them. d. he failed to seal his flasks of boiled broth. e. he allowed his assistant to conduct the experiment which he did not monitor closely.

An organism's reproductive strategy includes all of the following except a. the number of offspring produced. b. the amount of energy expended in producing offspring. c. the length of time parental care is given d. the number of alleles an organism passes on.