When did life first appear on the planet?
A. 2.1 billion years ago
B. 3.5 billion years ago
C. 2.1 million years ago
D. 3.5 million years ago
Answer: B
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Laboratory strains of E. coli ____
a. undergo meiosis b. divide every 2 hours c. can be transformed but not conjugated d. have been engineered to produce human insulin e. are harmful to humans
The ____ is most like an endoskeleton
a. wooden frame of a house b. covering of a chair c. hair of a dog d. trunk of a tree e. handle of a umbrella
Smog forms when pollutants in the air react with each other in the presence of sunlight and carbon dioxide
Indicate whether the statement is true or false
Biologists are studying two species whose DNA is known to differ by 10%. Which information would be least important in calibrating a molecular clock to determine how rapidly evolution has proceeded with these two species?
A) the fossil record of these two species B) a geological event that separated the species at a particular time C) the function of each of these regions of DNA D) the time of divergence of closely related species