The Cambrian Explosion Resulted in the Evolution of More Than

question 74

Multiple Choice

The Cambrian explosion resulted in the evolution of more than 17,000 species of an animal known as the trilobite.The shear number of trilobite fossils found in modern times suggests that trilobites were very abundant,perhaps the rulers of the seas.Today,no living descendants of this group exist.What happened?

• A) Because trilobites evolved before the first mass extinction, it is possible that one or more of the five mass extinctions could have eventually wiped out the entire group.
• B) In order to disappear from the planet entirely, trilobites must have undergone the process of adaptive radiation.
• C) It is unlikely that trilobites could have survived the increase in atmospheric oxygen once the process of photosynthesis had evolved.
• D) Being so plentiful, trilobites must have been the major food source for terrestrial dinosaurs. The extinction of the trilobite may have caused the mass extinction of dinosaurs.

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Definitions:

Venomous Snake

A snake that produces venom, a toxic substance used predominantly for immobilizing or killing prey and for defense against predators.

Cytokines

Small proteins released by cells that have a specific effect on the interactions and communications between cells or on the behavior of cells.

White Blood Cell

Leukocyte, of which there are several types, each having a specific function in protecting the body from invasion by foreign substances and organisms.

Universal Donor

A term often associated with blood type O negative, referring to individuals whose red blood cells can be transfused into persons of any other blood type without causing an adverse reaction.