Human Impact on the Environment — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. The Amazon rainforest is sometimes called the 'lungs of Earth' because it ___.
A) Produces large amounts of oxygen and stores carbon
B) Inhales air through tree leaves like human lungs
C) Cools the planet by reflecting sunlight away
D) Makes most of the world's drinking water flow
Rainforest trees pull in carbon dioxide and release oxygen during photosynthesis.
2. Which choice is the BIGGEST direct cause of Amazon deforestation today?
A) Heavy rainfall washing trees away
B) Clearing land for cattle ranching and soy farms
C) Volcanic eruptions in nearby mountains
D) Tourists camping inside the forest
Most cleared Amazon land becomes pasture or soy fields, not natural disturbance.
3. A community plants 10,000 native trees beside a cleared area. The BEST predicted outcome is ___.
A) Instant return of every original animal species
B) All nearby rivers immediately doubling in size
C) Gradual habitat recovery and slow return of wildlife
D) Permanent end of all global climate change
Reforestation rebuilds habitat slowly, allowing animals to return over years.
4. Compare two solutions: (A) banning all logging vs (B) allowing certified sustainable logging. Which statement is MOST accurate?
A) A is impossible to enforce, so B is the only option ever used
B) B can balance income and forest survival when rules are followed
C) A always destroys local economies completely with no benefit
D) B causes more deforestation than illegal logging in every case
Sustainable certified logging, when enforced, balances economy with conservation needs.
Part B: Fill in the Blank
Write the correct answer on each line.
1. The Amazon stores huge amounts of carbon inside its trees and soil.
Burning rainforest releases stored carbon dioxide, accelerating climate change.
2. Cutting trees to clear land for farming is called deforestation.
Deforestation removes habitat and releases greenhouse gases into the air.
3. Replanting trees on cleared land is called reforestation.
Reforestation rebuilds habitat and pulls carbon back out of the atmosphere.
4. Indigenous peoples have managed Amazon land sustainably for thousands of years.
Indigenous stewardship protects biodiversity better than many government efforts.
5. An ecosystem with many different species has high biodiversity.
Biodiversity supports food webs, medicines, and resilience to disturbance.