RC3: 7.BG Quiz 1

The scientific explanation in this news report reveals that the family of splay-footed crickets is it in a state of stasis. This is true because the shape and functions of species belonging to this family have- 

• changes dramatically over many years. 
• changed to a new species over many years. 
• not changed dramatically over many years.
• not changes at all over many years. 

Some scientists think that complex eukaryotic cells formed from the union of two seperate prokaryotic cells. The engulfing of one prokaryotic cell by another is a plausible explanation of why -

• eukaryotic cells lack the defense mechanisms of prokaryotic cells. 
• organelles in a eukaryotic cell would attach a prokaryotic cell. 
• eukaryotic cells dont share any similarities with prokaryotic cells. 
• organelles in a eukaryotic cell work cooperatively. 

According to the endosymbiotic theory, eukaryotic cells came to exist because prokaryotic cells surrounded and incorporated bacteria. These bacteria eventually became organelles. Biologists disagree as to whether prokaryotic cells engulfed bacteria only once or on multiple occasions. If prokaryotic cells engulfed bacteria on multiple occasions, there would be clearer understanding of why eukaryotic cells found in different species possess- 

• no complex structures. 
• similar complex structures. 
• identical complex structures. 
• different complex structures. 

In a certain area containing undisturbed layers of rock, fossils of horseshoe crabs may be found in the upper layer, and fossils of trilobites in the lower layer. Trilobites are extinct aquatic arthropods resembling modern horseshoe crabs. This information suggests that-

• horseshoe crabs may have developed from trilobites. 
• trilobites may have developed from horseshoe crabs. 
• horseshoe crabs and trilobites are unrealistics. 
• horseshoe crabs and trilobites are both extinct. 

Which concept is best illustrated by the physical variations in the horse as its size and structures changes over time?

• punctuated equilibrium over two generationsg
• gradual adaptation over successive generations
• acquired characteristics 
• artificial selection