HELP Thousands of golden toads, shown below, used to occupy the tropical forests of Costa Rica.
In the late 1980s, however, unusually warm weather caused many of the pools that the toads used as breeding areas to dry up. By
2004, the golden toad was listed as extinct.
This example demonstrates how
A. extinction is directly related to human impact.
B. extinction is caused by bacteria, fungi, and other infectious agents.
C. extinction can be related to invasion by non-native species competing for resources.
D. extinction can be related to a failure to adapt to changes in the environment.

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it

Aristotle classified animals according to their a. habitat and mating behavior c. mating behavior and relatedness b. habitat and physical differences d. physical differences and mating behavior