basic units of the dna molecule composed of a sugar, phosphate, and one of four dna bases is called a(n):

What was the land like over 500 million years ago? what was under the sea?

Look at the photo of the leaf, which term best describes this leaf ? a-simple. b-parallel. c-lobed. d-tooth.

Which of the following observation darwin shape his concept of descent with modification? a) species diversity declines farther from the equator. b) fewer species live on islands than on the nearest continents. c) birds live on islands located farther from the mainland than the bird's maximum nonstop flight distance. d) south american temperate plants are more similar to the tropical plants of south america than to the temperate plants of europe. e) earthquakes reshape life by causing mass extinctions.