What makes up the 'rungs' of the dna molecule?

Scientist have long study the earths climate by looking at which of the following? the earths orbit. the earths rock layers. the antarctic ice. the earths oceans.

As , plants meet their needs for making food from air, soil, water, and the sun's energy in a process called there are plants called grow high in trees without here are words to put in the blanks. 1.) producers 2.) consumers 3.) chloroplasts 4.) epiphytes

Which of the following is a true statement? a. individuals evolve to have adaptations. b. individuals have adaptations that can change over time. c. individuals have traits that may or may not make them successful at reproduction. d. populations cant evolve, only individual organisms.