AP Environmental Science Unit 9: Global Change practice questions

Question 1

What is the stratospheric ozone layer and why does life on Earth depend on it?

Accepted Answer

Stratospheric O₃ that absorbs UV radiation, shielding life from DNA damage. Without it, surface organisms would suffer severe UV damage.

Answer

A layer of oxygen gas that traps infrared radiation and warms Earth's surface

Answer

A tropospheric pollutant that filters out visible light and reduces photosynthesis

Answer

A chemical barrier that neutralizes acid rain before it reaches the surface

Question 2

How do chlorofluorocarbons (CFCs) destroy stratospheric ozone?

Accepted Answer

UV splits CFCs, freeing chlorine atoms that catalytically destroy up to 100,000 ozone molecules each. The chlorine isn't consumed, so it keeps destroying ozone.

Answer

CFCs absorb UV radiation that would otherwise form ozone, starving the ozone layer of its energy source

Answer

CFCs bond directly to ozone molecules and convert them into stable, non-reactive compounds

Answer

CFCs release fluorine atoms that react with ozone and permanently remove it from the stratosphere

Question 3

A thinning ozone layer allows more UV radiation to reach Earth's surface. What are two documented health effects on humans?

Accepted Answer

Increased risk of skin cancer and cataracts.

Answer

Increased rates of respiratory disease and hearing loss

Answer

Higher incidence of vitamin D deficiency and rickets

Answer

Greater risk of cardiovascular disease and kidney failure

Question 4

Besides CFCs, what natural factor accelerates ozone depletion over Antarctica each spring?

Accepted Answer

Melting polar stratospheric ice crystals in early Antarctic spring release trapped reactive chlorine. That freed chlorine intensifies ozone breakdown.

Answer

Increased solar radiation during the Antarctic spring raises UV intensity, directly photodissociating ozone faster

Answer

Methane released from thawing permafrost reacts with ozone molecules over the South Pole

Answer

Volcanic eruptions near Antarctica release sulfur dioxide that catalytically destroys ozone

Question 5

What chemical class was developed to replace ozone-depleting CFCs, and what is the key environmental trade-off?

Accepted Answer

Hydrofluorocarbons (HFCs) replaced CFCs and spare the ozone layer, but many are potent greenhouse gases. They trade an ozone problem for a high global-warming-potential one.

Answer

Hydrochlorocarbons (HCCs) replaced CFCs and have no environmental side effects at current atmospheric concentrations

Answer

Perfluorocarbons (PFCs) replaced CFCs and are completely inert in both the stratosphere and troposphere

Answer

Nitrogen oxides replaced CFCs as refrigerants and actually help replenish stratospheric ozone over time

Question 6

Compare CFCs and HFCs: how are they similar, and where do they critically differ in terms of environmental impact?

Accepted Answer

Both are synthetic refrigerants; CFCs both deplete ozone and trap heat, while HFCs only trap heat. HFCs spare the ozone but remain potent greenhouse gases.

Answer

HFCs deplete ozone at a slower rate than CFCs but are otherwise identical in their climate impact

Answer

CFCs are greenhouse gases while HFCs are not, making HFCs the superior long-term environmental choice

Answer

Both CFCs and HFCs are fully inert in the troposphere and only become reactive in the stratosphere

Question 7

Name the five principal greenhouse gases identified in the CED.

Accepted Answer

Carbon dioxide (CO₂), methane, water vapor, nitrous oxide, and CFCs. These five trap heat; nitrogen and oxygen don't.

Answer

Carbon dioxide, ozone, hydrogen, nitrogen oxide, and sulfur dioxide

Answer

Carbon dioxide, methane, argon, nitrous oxide, and particulate matter

Answer

Water vapor, carbon monoxide, methane, ammonia, and hydrocarbons

Question 8

Water vapor is a greenhouse gas. Why doesn't it significantly drive long-term global climate change the way CO₂ does?

Accepted Answer

Water vapor has a very short residence time — it rains out quickly, so it doesn't accumulate like CO₂. Precipitation removes it fast, unlike long-lived CO₂.

Answer

Water vapor absorbs a different wavelength of infrared radiation than CO₂, so it does not contribute to the same warming effect

Answer

Water vapor concentrations are too low in the atmosphere to have any measurable greenhouse effect

Answer

Water vapor is only found in the troposphere, which is too low in the atmosphere to trap significant heat

AP Environmental Science — Unit 9: Global Change

What AP Environmental Science Unit 9 covers

AP Environmental Science Unit 9 practice questions

Key terms in Unit 9

Drill all of Unit 9 with spaced repetition