A Level Biology Practice Exam

Which organisms are described as autotrophic?

1. Organisms that consume other organisms for nutrients

2. Organisms that acquire nutrients through photosynthesis

3. Organisms that rely on organic compounds for energy

4. Organisms that are incapable of photosynthesis

The correct answer is: Organisms that acquire nutrients through photosynthesis

The correct answer identifies autotrophic organisms as those that acquire nutrients through photosynthesis. Autotrophs are capable of producing their own food by converting light energy, typically from the sun, into chemical energy through the process of photosynthesis. They utilize carbon dioxide and water to synthesize organic compounds, primarily glucose, while releasing oxygen as a byproduct. In contrast, the other options describe different nutritional strategies. Organisms that consume other organisms for nutrients represent heterotrophic behaviors, where they depend on other living beings for their energy and organic compounds. Those that rely on organic compounds for energy also fall under the heterotrophic category, as they cannot produce their own food and must obtain nutrients from pre-existing organic materials. Finally, organisms that are incapable of photosynthesis do not fit the definition of autotrophs since they lack the ability to convert light energy into usable chemical energy for their growth and survival.