A controlled experiment _____
A) is repeated many times to ensure that the results are accurate
B) includes at least two groups, one of which does not receive the experimental treatment
C) includes at least two groups, one differing from the other by two or more variables
D) includes one group for which the scientist controls all variables
B
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The ratio of toxic dose to therapeutic dose is called the
A. therapeutic index. B. phenol coefficient. C. susceptibility quotient. D. toxicity index.
Prior to the work of Mendel, inheritance was viewed as resulting from
An atom that normally has __________ in its outer shell would NOT tend to form chemical bonds with other atoms.
Fill in the blank(s) with the appropriate word(s).
Sporopollenin is
A. pollen that is produced in a sporophyte. B. a tough protective covering on spores. C. a capsule housing pollen. D. food stored in pollen for the growing embryo. E. the conversion of pollen to spores.