Specialized nerve cells called are responsible for communication in the nervous system

Nucleic acid certain protein cell membranes certain carbohydrates

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere

The smallest biological units that can evolve are