When the photosynthetic organisms evolved the ability to split water, they produced _____ as a waste material, which was poisonous to most of the cells then alive

a. hydrogen gas
b. hydrogen sulfide
c. water
d. carbon dioxide
e. oxygen


E; The earliest photosynthesizers used H2, H2S, and other sources of hydrogen atoms. Only when cells developed processes for splitting water did they begin to release O2 as a by-product.

Biology & Microbiology

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Glucose is converted into glycogen primarily in the ____

a. brain b. blood c. pancreas d. spleen e. liver

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Which of the following most often leads to allopatric speciation?

A. Habitat isolation B. Mating time differences C. Gametic incompatibility D. Behavioral isolation

Biology & Microbiology

Which of the following mutations is considered a synonymous change?

A) ACC to AUG B) CUU to AUU C) CUU to CUA D) CUU to CUA E) UUU to UUA

Biology & Microbiology

Which of the following does not contribute to limits on population growth?

a. snakes feeding on mice in a cornfield b. bears having two cubs c. the amount of light for photosynthesis d. a disease-causing organism entering a population e. an increase in the total rainfall in a normally dry environment

Biology & Microbiology