Which of the following best describes organisms that use autotrophic nutrition? They obtain food from feeding on other organisms. They do not require food but survive off water alone. They are able to synthesize their own food from simple inorganic materials. Or they automatically detect when food is present in an area.
Let’s start by defining some of the key terms in the question to better understand how to answer it. An organism is an individual living entity, whether it’s a plant, an animal, or a single-celled life form such as a bacterium. Nutrition is a process by which living organisms assimilate or take in food materials. And these enable them to grow, to maintain themselves, and to reproduce. Autotrophic nutrition means that the organisms in question are autotrophs. Autotrophs are organisms which obtain their nutrition by synthesizing food within their own cells. This is really useful as it means they don’t need to rely on other organisms for their nutrition. This can be done, for example, by plants through the process of photosynthesis.
The tree pictured here is an example of a plant which carries out autotrophic nutrition. Plants use light energy to convert water and carbon dioxide into glucose, which they can use as a source of chemical energy. This process is called photosynthesis. The glucose will then be used in a process called cellular respiration in order to release energy for the plant to use. The auto- in autotroph means self, while the -troph means food, which is referring to how autotrophs make their own food. Autotrophs like this tree, however, are not the only type of nutrition that exists. There are also organisms which are heterotrophs. Hetero- means different, and it refers to the way in which heterotrophs, like this rabbit, obtain their nutrition by consuming other organisms.
In this example, the rabbit is consuming a carrot. The carrot is itself a living organism, which makes a rabbit heterotrophic. Heterotrophs can come in lots of different forms. But the thing that unifies them is the fact that they obtain their nutrition by taking in the nutrients from another organism. Autotrophs do not rely on other organisms like heterotrophs do, so we can eliminate option (A) as they do not obtain their food by feeding on other organisms. Though it will be very impressive if autotrophs could detect when food is present in an area, this is not one of their features, which eliminates again option (D).
Though autotrophs do require water, as you can see, for example, it’s one of their reactants in photosynthesis among its many other functions, they cannot survive on just water alone as they need carbon-containing organic compounds like glucose, which they’re going to synthesize in their own cells from simple inorganic materials such as carbon dioxide. This eliminates option (B).
Therefore, our best description of organisms which use autotrophic nutrition is that they’re able to synthesize their own food from simple inorganic materials.