Why do oxygen and carbon dioxide move in and out of a plant during the day? A. Because the plant is only photosynthesizing
B. Because the plant is both respiring and photosynthesizing
C. Because the plant is only respiring
D. Because the plant is neither photosynthesizing nor respiring

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.