A niche can be defined as 

A population is defined as 

The epithelium best adapted for a body surface subject to abrasion is

The advantage of excreting wastes as urea rather than as ammonia is that

Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species?

The sequence of developmental milestones proceeds as follows:

In 2012 a British teenager celebrated her birthday by drinking a cocktail made with liquid nitrogen and alcohol.  The liquid nitrogen froze her stomach, and her stomach had to be removed surgically.  Given what you know about the function of the digestive tract, what potential implications might removing a person’s stomach have for that person’s ability to digest food?  What might that person now have to consider doing to ensure proper nutrition?   Explain your reasoning.

The following questions refer to the digestive system structures in Figure 41.1. Figure 41.1 Where does the digestion of fats mostly occur?

More than one answer may be correct.  Please check all correct answers. To increase the effectiveness of exchange surfaces in the lungs and in the intestines, evolutionary pressures have

Food moves along the digestive tract as the result of contractions by