One of the strongest lines of evidence of a meteor or comet impact in the late Cretaceous is

A) the extinction of the dinosaurs in only South America.
B) a thin layer of potassium-40 in late Cretaceous fossil strata.
C) a thin layer of iridium-enriched clay in late Cretaceous fossil strata.
D) the warming of Earth's climate in the late Cretaceous.


Answer: C

Biology & Microbiology

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Reproduction by cell division:

A. results in two daughter cells that are genetically identical. B. is asexual reproduction. C. persists in mature plant cells for continued growth. D. continues in mature adult humans to replace damaged and worn-out cells. E. All of these choices are correct.

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If the first electron transfer chain in the lightdependent

reactions of photosynthesis was stopped, which of the following would NOT be generated?

a. oxygen gas b. NADPH c. ATP d. ATP and NADPH e. none of these would be generated

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People who have a single X chromosome are female, while those with XXY sex chromosomes are males. In order to be a female, a human

A. cannot have an X chromosome. B. must have only one X chromosome. C. must have two X chromosomes. D. cannot have a Y chromosome. E. must have only one Y chromosome.

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DNA replication in eukaryotes ________

A) takes place multiple times per cell cycle B) synthesizes DNA approximately 25 times faster than in prokaryotes C) occurs without the need of a primer D) utilizes a single type of DNA polymerase E) initiates at multiple origins

Biology & Microbiology