Major Extinctions of Dinosaurs Are Associated with Large Meteor Impacts

question 8

Multiple Choice

Major extinctions of dinosaurs are associated with large meteor impacts, including the final extinction that wiped them out at the Cretaceous-Tertiary boundary.The particulate matter that would have arisen as a result of impact would have entered the atmosphere and had secondary impacts.Some scientists believe that a fundamental difference between mammals and dinosaurs allowed mammals to survive this event, but doomed the dinosaurs.What may have characterized the last generation of dinosaurs as they went extinct?

• A)Lungs clogged with dust.
• B)Highly skewed sex ratios.
• C)Hormonal disruptions due to contaminated water.
• D)Weak eggshells due to radiation.

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Definitions:

Mitotic Spindle

A structure composed of microtubules that forms during cell division to separate chromosomes into each of the two daughter cells.

Anaphase

Stage of mitosis in which the chromosomes move to opposite poles of the cell; anaphase occurs after metaphase and before telophase.

Centromere

A specialized constricted region of a chromatid; contains the kinetochore. In cells at prophase and metaphase, sister chromatids are joined in the vicinity of their centromeres.

Nucleosomes

Structural units of a chromosome, consisting of a segment of DNA wound around a core of histone proteins.