Question Video: Defining the Term “Autotrophic” | Nagwa Question Video: Defining the Term “Autotrophic” | Nagwa

Question Video: Defining the Term “Autotrophic” Biology

Organisms belonging to the kingdom Plantae are autotrophic. Which of the following best explains what this means? [A] Autotrophic organisms obtain their food through consuming other organisms. [B] Autotrophic organisms can produce their own food using inorganic materials. [C] Autotrophic organisms are able to grow in nutrient-free environments.

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Video Transcript

Organisms belonging to the kingdom Plantae are autotrophic. Which of the following best explains what this means? (A) Autotrophic organisms obtain their food through consuming other organisms. (B) Autotrophic organisms can produce their own food using inorganic materials. Or (C) autotrophic organisms are able to grow in nutrient-free environments.

Our question deals with organisms within the kingdom Plantae, the plants. This kingdom includes not only familiar types of plants, such as pine trees, tulips, and cacti, but also lesser known groups, such as the liverworts and whisk ferns. It is worth noting that based on molecular data, many scientists have adopted an expanded version of kingdom Plantae that includes red and green algae, although this continues to be debated.

If you have ever taken care of a plant, you already know that they don’t need to be fed the same way that humans do or that a pet might. They do require some basic nutrients, which they get from soil, as well as water, air, and sunlight. But how do plants use these materials to make the energy they need to grow and reproduce? Plants are able to produce their own food through photosynthesis, a process that uses the energy from sunlight to produce glucose and oxygen from water and carbon dioxide. The reactants of the photosynthesis equation are carbon dioxide and water. Neither of these molecules contain carbon–hydrogen bonds, so they are inorganic substances.

During photosynthesis, structures inside of plant cells called chloroplasts will use energy from photons of light to initiate the conversion of inorganic carbon dioxide and water into the organic compound glucose, releasing oxygen in the process. Glucose is then used to make more organic molecules, including starch, cellulose, amino acids, and lipids. It also powers cellular respiration to create energy in the form of ATP.

Looking at the term autotroph, you may recognize the prefix auto-, which means self, and the root word -troph, which means nourishment or food. Because plants are able to produce their own food source through photosynthesis, they are classified as autotrophs. Organisms that produce their own food through chemosynthesis, which relies on energy from the oxidation of inorganic molecules rather than light energy, are also categorized as autotrophs.

In contrast, organisms that cannot produce their own organic compounds are known as heterotrophs. The prefix hetero- means other, and we already know that -troph means food. So, heterotrophs get their nourishment from consuming other organisms instead of making it themselves like plants.

Now that we have covered the difference between autotrophs and heterotrophs, let’s take a look back at our question. It asks us for the best explanation of autotrophs. And we’ve just learned that autotrophs are organisms, like plants, that are able to produce their own food from inorganic substances. So, the correct answer to our question is (B). Autotrophic organisms can produce their own food using inorganic materials.

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