Question detail
What is the approximate percentage of oxygen in the Earth's atmosphere, and why is this significant for life on Earth?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
The composition and evolution of the Earth's atmosphere
Question
What is the approximate percentage of oxygen in the Earth's atmosphere, and why is this significant for life on Earth?
Answer
The approximate percentage of oxygen in the Earth's atmosphere is about 20 percent. This is significant for life on Earth because oxygen is essential for the process of respiration in animals and is also involved in combustion, which is necessary for energy production.
Explanation
A strong answer should directly address the approved learning objective to explain why percentage composition is useful when describing atmospheric gases. This question belongs to The proportions of different gases in the atmosphere within The composition and evolution of the Earth's atmosphere, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to percentage composition, and keeps the wording specific to AQA GCSE revision.
Common mistake
Misunderstanding Percentage Composition
Students often confuse percentage composition with absolute amounts of gases, thinking it refers to the total volume rather than the proportion of each gas in the atmosphere.
Emphasize that percentage composition describes the relative proportions of each gas in the atmosphere, helping to understand the significance of each gas's presence.
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