Today, the fossil record
A. can be dated precisely, to within a single year, using radioactive isotopes.
B. can be dated reasonably well using a variety of radioactive isotopes with known half-lives.
C. can be dated reasonably well only with uranium-238.
D. can be dated only with one layer in relation to older layers below and younger layers above, no actual dates can be estimated.
E. can be dated precisely, to within a single year, using DNA hybridization.
Answer: B
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a. gibberellin b. auxins c. 1-methylcyclopropene (MCP) d. ethylene
Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have severe respiratory problems due to defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. Which of the following most likely explains the effect of the recessive allele?
(A) The mitochondria are defective and do not produce sufficient protein to synthesize microtubules in the cilia and flagella. (B) The plasma membrane of the alveoli is not permeable to carbon dioxide during respiration because it is too hydrophobic. (C) The Golgi bodies secrete an enzyme that destroys the proteins in the flagella and cilia. (D) The cells do not produce functional motor proteins in flagella and cilia.
Which of the following best describes the process of DNA replication?
(A) Multiple "bubbles" form in the DNA and proceed with replication in both directions from the bubble (B) A single "bubble" forms in the DNA and proceeds with replication in a single direction from the bubble (C) DNA polymerase adds nucleotides to each separated strand of the DNA molecule at the replication fork, replication two leaded strands at one end of the "bubble" and two lagging strands at the other side of the "bubble" (D) Replication occurs at a single replication fork that replications lagging and leading strands in the same direction
What is the best explanation for the origin of the unique species recently found in the Annamite Mountains of Vietnam?
A) Temporal isolation B) Allopatric speciation C) Adaptive radiation D) Behavioral isolation E) Sympatric speciation