How does crossing over contribute to genetic variation

Which of the following is true of photosynthesis? a)carbon dioxide is a reactant b)water is a product c)most reactions within this process are exothermic d)oxygen is a reactant

Which of the following are false concerning microbes? a. microbes generate oxygen through photosynthesis.b. the primary role of microbes on the planet involves causing disease in animals and humans.c. microbes produce vitamins in the intestines.d. microbes play a role in breaking down waste and decomposing dead organisms.

Were does condensation occur? a) hydroshereb) lithosherec) boishered) atmosphere