Human Impact on the Environment is one of 10 topics in the Grade 11 Life Sciences CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. The greenhouse effect is best described as:
Greenhouse gases absorbing and re-radiating infrared radiation, trapping warmth in the atmosphere
A process that removes all heat from Earth's atmosphere
A process found only on other planets, not Earth
The complete blocking of sunlight from reaching Earth's surface
Answer: Greenhouse gases absorbing and re-radiating infrared radiation, trapping warmth in the atmosphere — The greenhouse effect is the natural process by which greenhouse gases absorb and re-radiate infrared (heat) radiation, trapping warmth within Earth's atmosphere and keeping the planet warm enough to support life.
Easy
2. What is the main human activity that has substantially increased atmospheric carbon dioxide concentration since the Industrial Revolution?
The burning of fossil fuels (coal, oil, and natural gas)
Increased photosynthesis by newly planted forests
A worldwide decrease in the number of factories
A reduction in the number of livestock farmed globally
Answer: The burning of fossil fuels (coal, oil, and natural gas) — Burning fossil fuels for electricity generation, transport, and industry releases carbon dioxide that had been locked away in the ground for millions of years, substantially increasing atmospheric carbon dioxide concentration since the Industrial Revolution.
Medium
3. Why does large-scale deforestation contribute to climate change in two distinct ways?
It releases stored carbon and reduces the planet's capacity to absorb further carbon dioxide through photosynthesis
It only affects local rainfall and has no connection to atmospheric carbon dioxide
It increases the number of trees available to absorb carbon dioxide
It has no effect on atmospheric greenhouse gas concentration at all
Answer: It releases stored carbon and reduces the planet's capacity to absorb further carbon dioxide through photosynthesis — Deforestation releases carbon that was stored in trees and soil, while also reducing the number of living trees available to absorb further carbon dioxide from the atmosphere through photosynthesis, contributing to climate change in two distinct, compounding ways.
