When cells are grown in a laboratory, which of the following is a factor that can stop normal cells from dividing?
A) contact with other cells
B) growth factors
C) a cut in the skin
D) injection of cyclin
Ans: A) contact with other cells
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When two lines stem from a single branch point on a phylogenetic tree, what are they called?
a. branch points b. leaves c. sister taxa d. species
The DNA sequence 5' ATGCCTGAATCAGCTTTA 3' could encode a maximum of ____ amino acids in a protein.
A) 5 B) 6 C) 7 D) 18
During the third phase "3", the population
growth slows and then levels off because
a. essential resources become scarce. b. the carrying capacity has been reached. c. competition for food becomes increasingly important. d. predators eat fawns as they are born. e. all of these occur except "predators eat fawns as they are born."
How can endospore-forming Firmicutes be selected?
a. by creating an anoxic environment b. by heating the sample for 10 min at 80°C c. by treatment with a strong dosage of ethylene gas d. none of the above