answer:
key points:
producers, or autotrophs, make their own organic molecules. consumers, or heterotrophs, get organic molecules by eating other organisms.
a food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another.
in a food chain, each organism occupies a different trophic level, defined by how many energy transfers separate it from the basic input of the chain.
food webs consist of many interconnected food chains and are more realistic representation of consumption relationships in ecosystems.
energy transfer between trophic levels is inefficient (with a typical efficiency around 10\%10%10, percent). this inefficiency limits the length of food chains.
introduction
organisms of different species can interact in many ways. they can compete, or they can be symbionts (long-term partners with a close association). or, of course, they can do what we so often see in nature programs: one of them can eat the other. (chomp! ) that is, they can form one of the links in a food chain.
in ecology, a food chain is a series of organisms that eat one another (so that energy and nutrients flow from one to the next). for example, if you had a hamburger for lunch, you might be part of a food chain that looks like: grass \rightarrow→right arrow cow \rightarrow→right arrow human. but what if you had lettuce on your hamburger? in that case, you're also part of a food chain that looks like: lettuce \rightarrow→right arrow human.
as this example illustrates, we can't always fully describe what an organism (such as a human) eats with one linear pathway. for situations like that, we may want to use a food web, which consists of many intersecting food chains and represents the different things an organism can eat, and be eaten by.
in this article, we'll take a closer look at food chains and food webs, seeing how they represent the flow of energy and nutrients through ecosystems.
autotrophs vs. heterotrophs
what basic strategies do organisms use to get food? some organisms, called autotrophs (“self-feeders”), can make their own food – that is, their own organic compounds – out of simple molecules like carbon dioxide. there are two basic types of autotrophs:
photoautotrophs, such as plants, use energy from sunlight to make organic compounds (sugars) out of carbon dioxide in photosynthesis. other examples of photoautotrophs include algae and cyanobacteria.
chemoautotrophs use energy from chemicals to build organic compounds out of carbon dioxide (or similar molecules). this is called chemosynthesis. for instance, there are hydrogen sulfide-oxidizing chemoautotrophic bacteria found in undersea vent communities (where no light can reach).
autotrophs are the foundation of every ecosystem on the planet. that may sound dramatic, but it's no exaggeration! autotrophs form the base of food chains and food webs, and the energy they capture from light or chemicals sustains all the other organisms in the community. when we're talking about their role in food chains, we can call autotrophs producers.
heterotrophs (“other-feeders”) such as humans can't capture light or chemical energy to make their own food out of carbon dioxide. instead, they get organic molecules by eating other organisms or their by-products. animals, fungi, and many bacteria are heterotrophs. when we're talking about their role in food chains, we can call heterotrophs consumers. as we'll see shortly, there are many different kinds of consumers with different ecological roles, from plant-eating insects to meat-eating animals to fungi that feed on debris and wastes.
food chains
now, we can take a look at how energy and nutrients move through a ecological community. let's start by considering just a few “who eats whom” relationships – that is, by looking at a food chain.
a food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. let's look at the parts of a typical food chain, starting from the bottom (the producers) and moving upward.
basically one organism in a level in a food chain will result in the one at the top being most likely to kill the rest. meaning the others do not stand a chance
explanation:
