Natural Science CLEP Prep Practice Exam

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Prepare for the CLEP Natural Science Exam with our comprehensive study materials and practice questions. Test your knowledge and ace the exam by mastering key concepts.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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What is the primary source of energy for most ecosystems?

Carbon dioxide
Sunlight
Oxygen
Water

The correct answer is: Sunlight

Most ecosystems rely on sunlight as their primary source of energy. Carbon dioxide is necessary for photosynthesis, but it is not the primary source of energy. While oxygen is necessary for life, it is not the primary source of energy. And while water is necessary for life, it is not the primary source of energy in most ecosystems. Sunlight provides the energy needed for photosynthesis, which is the process by which plants and other organisms convert light energy into chemical energy, making it the primary source of energy for most ecosystems.