46.5 The Ecological Framework of Biodiversity

Which of these factors likely contributed to the accumulation of O2 within Earth's atmosphere?

- the evolution of cyanobacteria - the fact that O2 is also cycled during the carbon cycle - the fact that photosynthesis releases O2 as a product - the fact that there is a slight "de-coupling" between photosynthesis and respiration

Which of the following statements explains how an oxygen-rich atmosphere was possible?

Rates of oxygen consumption are lower than rates of photosynthesis.

True or false? If all of the tertiary consumers were removed from an environment, the associated food web, and thus the carbon cycle, would collapse.

false, the food web would likely be greatly altered, and the biomass at each trophic level would change. If tertiary consumers were removed, there would be an increase in secondary consumers. The secondary consumers would then decimate primary consumer populations, and primary producers would increase. The carbon cycle would not collapse, as it is a global and not a local cycle.

Which of these organisms can incorporate atmospheric carbon directly into C6H12O6, thereby playing a major role in a food web?

primary producers

Decomposers are vital components of a food web because they:

return carbon (as CO2) to the atmosphere.

True or false? The evolution of biodiversity on the planet can be linked to patterns in the carbon cycle over time.

true