Oxygen (O2) makes up about 21% of the Earth's atmosphere. The graph below depicts changes in atmospheric O2 levels measured between the years 1990 and 2008. The burning of fossil fuels produces CO2, removing O2 from the atmosphere
It has been
estimated that approximately three molecules of O2 are consumed by every single molecule
of CO2 produced by fossil fuel combustion. Over about 20 years, a total loss of 0.0317% O2
from the atmosphere was calculated from this data. If you compare this graph to that shown
in Figure 25.1, how is the trend in O2 levels related to the trend in CO2 levels?
A. Both O2 levels and CO2 levels increase
over time.
B. Both O2 levels and CO2 levels decrease
over time.
C. O2 levels decrease as CO2 levels
increase.
D. O2 levels increase as CO2 levels
decrease.
C
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Suppose that some marine bacteria that are normally bioluminescent are NOT any more. As a result, what would the bacteria most likely be unable to do?
a. They would be unable to scare off potential predators. b. They would be unable to feed. c. They would be unable to communicate. d. They would be unable to reproduce.
The small circles of DNA found in bacteria are called GENOMES.
a. true b. false
In the vertebrate eye, what structure is light focused onto?
A. Retina B. Pupil C. Sclera D. Lens E. Iris
On an axon, the small spacings between the insulation surrounding the axon are called
A. trigger zones. B. axons. C. synapses. D. dendrites. E. nodes of Ranvier.