What causes photochemical smog?
a. it is formed by reactions involving sunlight and nitrous oxides and hydrocarbons released from automobile exhaust.
b. it is formed from sulfur oxides and particulate matter released from combustion of combustion of heating oil and coal.
c. it is formed by reactions between cfcs from industrial processes and ice crystals in the upper atmosphere.
d. it is formed when secondary pollutants such as ozone combine with primary pollutants such as hydrocarbons in cold winter temperatures?

You can tell from this karyotype that the individual is female because the karyotype has two chromosomes labeled

Clara wrote the following hypothesis for an experiment about acidophilic bacteria. bacteria cells will stop dividing in a basic (alkaline) environment because of the high ph. which statement is the best way to restate the hypothesis so that it is more specific? growing acidophilic bacteria in some environments will cause the cells to stop dividing because of ph. if the ph of their environment is changed, acidophilic bacterial cell division will be affected. if the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing. the more alkaline an environment, the less cell division will occur in bacteria.

Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak