Which level of the biosphere includes both living and nonliving factors?

All the organisms on your campus make up

a. An ecosystem

b. A community

c. A population

d. The biosphere

A biologist studying interactions among the bacteria in an ecosystem could not be working at which level in life's hierarchy? (Choose carefully and explain your answer.)

a. The population level

b. The molecular level

c. The organism level

d. The organ level

Draw a biological hierarchy similar to the one in Figure 1.3 but using a coral reef as the ecosystem, a fish as the organism, its stomach as the organ, and DNA as the molecule. Include all levels in the hierarchy.

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Biology can be described as having both a vertical scale and a horizontal scale. Explain what that means.