1. Performance Benchmark E.12.A.2 Students know the composition of Earth’s atmosphere has changed in the past and is changing today. High School Science Proficiency Review

2. By percentage, the three most abundant gases in Earth’s atmosphere are: a. carbon dioxide, krypton, and neon b. hydrogen, helium, and xenon c. argon, nitrogen, and oxygen d. sulfur dioxide, ammonia, and chlorine

3. By percentage, the three most abundant gases in Earth’s atmosphere are: a. carbon dioxide, krypton, and neon b. hydrogen, helium, and xenon c. argon, nitrogen, and oxygen d. sulfur dioxide, ammonia, and chlorine The atmosphere is made of approximately 78% nitrogen, 21% oxygen, 1% argon, and a fraction of a percent of about 8 other compounds.

4. The most variable gas in our atmosphere is: a. oxygen b. water vapor c. carbon dioxide d. nitrogen

5. The most variable gas in our atmosphere is: a. oxygen b. water vapor c. carbon dioxide d. nitrogen The amount of water vapor in the atmosphere fluctuates greatly and can range anywhere from just above zero to about three percent.

6. The term “anthropogenic emissions” refers to greenhouse gases released into the atmosphere as a result of human activities. Study the accompanying graph to determine which statement is most accurate.

7. a. atmospheric concentrations of CO 2 have steadily decreased as anthropogenic emissions have steadily increased No – they are both increasing.

8. b. before 1850, humans were releasing so much CO 2 into Earth’s atmosphere that the values won’t even fit on the scale of this graph No – CO 2 was so low it is below the scale of this graph.

9. c. careful scrutiny of the graph reveals there is absolutely no correlation between anthropogenic emissions and atmospheric concentrations of CO 2 No – it looks like there is a trend.

10. d. since the 1960s, atmospheric concentrations of CO 2 have risen at a rate approximately equal to that of anthropogenic emissions Yes – this is the best choice. The rate may not be equal, but there is definitely a correlation.

11. a.atmospheric concentrations of CO 2 have steadily decreased as anthropogenic emissions have steadily increased b.before 1850, humans were releasing so much CO 2 into Earth’s atmosphere that the values won’t even fit on the scale of this graph c.careful scrutiny of the graph reveals there is absolutely no correlation between anthropogenic emissions and atmospheric concentrations of CO 2 d.since the 1960s, atmospheric concentrations of CO 2 have risen at a rate approximately equal to that of anthropogenic emissions

12. Certain atmospheric gases are thought of as “non-variable” since their abundance remains unchanged over vast periods of time. The two gases with the longest residence time in Earth’s atmosphere are: a. nitrogen and oxygen b. carbon dioxide and methane c. carbon monoxide and chlorine d. argon and helium

13. Certain atmospheric gases are thought of as “non-variable” since their abundance remains unchanged over vast periods of time. The two gases with the longest residence time in Earth’s atmosphere are: a. nitrogen and oxygen b. carbon dioxide and methane c. carbon monoxide and chlorine d. argon and helium Argon and helium are also relatively non- variable; however, nitrogen and oxygen is the best answer. 78% of atmosphere21% of atmosphere

14. Earth’s early atmosphere gained oxygen through photosynthesis and ____________. a. cellular respiration b. photochemical dissociation c. reverse osmosis d. nitrogen fixation

15. Earth’s early atmosphere gained oxygen through photosynthesis and ____________. a. cellular respiration b. photochemical dissociation c. reverse osmosis d. nitrogen fixation Uses up oxygen

16. Earth’s early atmosphere gained oxygen through photosynthesis and ____________. a. cellular respiration b. photochemical dissociation c. reverse osmosis d. nitrogen fixation Uses up oxygen N 2 + 16 ATP + 8e - + 8H + => 2NH 3 + 16 ADP + 16 P i + H 2

17. Earth’s early atmosphere gained oxygen through photosynthesis and ____________. a. cellular respiration b. photochemical dissociation c. reverse osmosis d. nitrogen fixation Uses up oxygen Has to do with water passing through a membrane

18. Earth’s early atmosphere gained oxygen through photosynthesis and ____________. a. cellular respiration b. photochemical dissociation c. reverse osmosis d. nitrogen fixation Uses up oxygen Must be photochemical dissociation, which is the breakdown of water by UV rays into oxygen and hydrogen.

19. Of the following, which provides evidence that Earth’s atmosphere was altered from that of a reducing atmosphere to an oxidizing atmosphere? a. volcanic outgassing poured vast quantities of water vapor into the atmosphere b. levels of carbon dioxide have steadily increased over the past several decades c. sediments rich in oxidized iron have been layered in thick deposits across the Earth d. the majority of hydrogen & helium has escaped Earth’s atmosphere into space

20. Of the following, which provides evidence that Earth’s atmosphere was altered from that of a reducing atmosphere to an oxidizing atmosphere? a. volcanic outgassing poured vast quantities of water vapor into the atmosphere b. levels of carbon dioxide have steadily increased over the past several decades c. sediments rich in oxidized iron have been layered in thick deposits across the Earth d. the majority of hydrogen & helium has escaped Earth’s atmosphere into space

21. Of the following, which provides evidence that Earth’s atmosphere was altered from that of a reducing atmosphere to an oxidizing atmosphere? c. sediments rich in oxidized iron have been layered in thick deposits across the Earth The rock layer is the only choice that provides evidence. Ancient cyanobacteria produced so much O 2 during the Proterozoic that by its end, around 545 million years ago, the atmosphere became oxidizing, as evidenced by the prevalence of deposits of red, iron-rich sediments.

22. Volcanic outgassing was a major source for Earth’s early atmosphere. Another source which contributed significant quantities of gases to the atmosphere was: a. sublimation of Earth’s polar ice caps and thawing of arctic permafrost b. widespread burning of the Earth’s forests c. ejection of gaseous matter from a nearby supernova d. comets impacting Earth, releasing gases as the comet vaporized

23. Volcanic outgassing was a major source for Earth’s early atmosphere. Another source which contributed significant quantities of gases to the atmosphere was: a. sublimation of Earth’s polar ice caps and thawing of arctic permafrost b. widespread burning of the Earth’s forests c. ejection of gaseous matter from a nearby supernova d. comets impacting Earth, releasing gases as the comet vaporized our atmosphere has been added to by influx of cometary gases contributed as comets burn up in the atmosphere. Our atmosphere has been added to by influx of cometary gases contributed as comets burn up in the atmosphere.

24. Which of the following are the two most abundant greenhouse gases in Earth’s atmosphere? a. water vapor (H 2 O) and carbon dioxide (CO 2 ) b. carbon dioxide (CO 2 ) and methane (CH 4 ) c. ozone (O 3 ) and carbon dioxide (CO 2 ) d. nitrogen (N 2 ) and oxygen (O 2 )

25. Which of the following are the two most abundant greenhouse gases in Earth’s atmosphere? a. water vapor (H 2 O) and carbon dioxide (CO 2 ) b. carbon dioxide (CO 2 ) and methane (CH 4 ) c. ozone (O 3 ) and carbon dioxide (CO 2 ) d. nitrogen (N 2 ) and oxygen (O 2 ) Be careful … nitrogen and oxygen are most abundant, but are not greenhouse gases.

26. Which of the following are the two most abundant greenhouse gases in Earth’s atmosphere? a. water vapor (H 2 O) and carbon dioxide (CO 2 ) b. carbon dioxide (CO 2 ) and methane (CH 4 ) c. ozone (O 3 ) and carbon dioxide (CO 2 ) d. nitrogen (N 2 ) and oxygen (O 2 ) Carbon dioxide and water vapor are the two most abundant greenhouse gases.