Which of the following hypotheses proposed to explain the evolutionary origin of viruses does not assume the pre-existence of living cells?
A. Viruses evolved from macromolecules.
B. Viruses evolved from plasmids that acquired genes for their own replication.
C. Viruses evolved by losing all the genetic information that is not absolutely required for reproduction.
D. The precursors of cellular DNA genomes may have been RNA molecules.
E. Viruses evolved from chromosomal elements.
D. The precursors of cellular DNA genomes may have been RNA molecules.
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Trilobites are extant.
A-True B-False
What are the two phases of photosynthesis?
a. chemiosmosis and photochemical reactions b. carbon reduction reactions and oxidation reactions c. light-dependent reactions and carbon fixation reactions d. carbon fixation reactions and oxygen fixation reactions e. light-independent reactions and carbon fixation reactions
Which of the following is NOT true about the eukaryotic cell cycle?
A. There are two stages to the cell cycle: M phase and interphase. B. The M phase consists of two events: mitosis and cytokinesis. C. Interphase is typically the shortest of the two stages of the cell cycle. D. There are three phases of interphase: the S phase and two gap phases. E. Some cells pause between M phase and S phase for more than a year. F. Some cells pause between the first gap phase and S phase for more than a year.
Which of the following events occur during anaphase I of meiosis?
A. The chromosome number is doubled during this phase of meiosis. B. In females, the two X chromosomes remain together. C. In males, the X chromosome is segregated from the Y chromosome. D. The centromeres of the chromosomes divide. E. Homologous chromosomes move as one unit.