The chemical composition of the gases surrounding the Earth has changed substantially over the past 4 billion years. One notable change was due to the emergence of photosynthetic organisms. The process of photosynthesis increased the amount of what gas in the atmosphere?

A. Water vapor (H2O).
B. Hydrogen sulfide (H2SO4).
C. Carbon dioxide (CO2).
D. Nitrogen (N2).
E. Oxygen (O2).


Answer: E

Biology & Microbiology

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Which of the following statements about the relationship between ants and acacia trees is/are accurate? Check all that apply.  

_____ The ants protect the acacias from other insects. _____   The ants protect the acacias from epiphytic plants and vines. _____ The ants live in the hollow thorns of the acacias. _____ The ants are provided with sugar or other nutrition by some species of acacia. _____  The ants aid pollination of the acacias.

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Which type of microscopy would be preferred for creating a three dimensional view of the distribution and arrangement of flagella on a bacterial cell surface?

A. Fluorescence microscopy B. Bright-field microscopy C. Transmission electron microscopy D. Scanning electron microscopy

Biology & Microbiology

Bacterial genes have introns, and eukaryotic genes lack introns

Indicate whether the statement is true or false

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Nauplius, a unique kind of larva, is characteristic of

A. crustaceans. B. mites. C. horseshoe crabs. D. insects. E. chelicerates.

Biology & Microbiology