A geneticist is studying sexual reproduction of a species of butterfly that lives in a very cold climate.  He hypothesizes that there should be low genetic diversity because it is well adapted to the cold climate but does not seem to be able to colonize surrounding areas with warmer climates.  What important principle is he using to formulate his hypothesis?

All animals must get oxygen to tissues for cellular respiration.  Which of the following is NOT involved in this critical function?

A species of beetle is active at night and sleeps in the bark of trees during the day.  These beetles normally mate during the night on the sides of trees.  The forest they live in has lizards that hunt insects by vision and birds that hunt insects by sounds made by their prey.  Which of the following represents the most adaptive way for male and female beetles to find each other for mating?

According to the phylogenetic tree below, modern-day mammals are most closely related to which modern group of reptiles?

The organ system that contains smooth muscle, epithelium, and endocrine cells, and involves organs such as the pancreas, liver, and pharynx, is the

On this temperature versus precipitation graph, the four areas plotted represent the ranges of temperatures and precipitations typical of four major types of biomes. Which choice correctly identifies the temperature and precipitation profiles for each type of biome?

All animals must get oxygen for respiration.  Which of the following is NOT involved in this critical function?

Why are parasites so difficult to classify based on morphology only?

Homeostasis in animals can be generally defined as the _____.

Which ecosystem would be least affected if sunlight did not reach the Earth for an extended period of time?