During the 1950's, several scientists were responsible for discovering the structure of dna. one scientist, erwin chargaff, found that in dna, the ratios of adenine (a) to thymine (t) and guanine (g) to cytosine (c) are always equal. which model best represents chargaff's rule?

Which geologic feature would most likely be represented by contour lines john far apart from one another? a cliff a hill a plain a valley

Match each description to the appropriate biome. tropical savanna desert tropical rain forest taiga tundra has sparse vegetation and very cold temperatures located near the equator and contains trees that form dense canopy layers is very hot and dry, and has plants that need little water has cold winters, heavy snowfall and is dominated by conifers has warm temperatures and is dominated by grasses

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important