Which statement is true?
a. hormones travel via specific pathways to specific cells, while electrical signals travel through the blood to all areas of the body.
b. effects of hormones last for brief periods of time, while effects of electrical signals last for long periods of time.
c. hormones have a direct connection with target cells, while electrical signals do not.
d. it takes longer for hormones to be released into the bloodstream and be taken to target cells than it does for electrical signals to be transmitted

Read the following scenario to answer the following question. over the past 60 years, many amphibian species have experienced significant population declines, and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. when most populations of a wide-ranging amphibian species are lost and the few remaining populations are widely separated, we expect to see that a. the founder effect becomes increasingly important b. microevolution no longer occurs c. gene flow between populations is reduced d. artificial selection becomes a greater factor in microevolution

Iguanas need to live in a habitat that is very warm, so the pet store warms their enclosures with "basking lights" which act as an artificial sun. describe how the three methods of thermal energy transfer may take place within the iguana's enclosure.

What element is able to combine with itself and hydrogen to form large molecules ?