What is the name of the groups of organisms that get their food from other organisms?
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Every plant and animal species, no matter how big or small, depends to some extent on another plant or animal species for its survival. It could be bees taking pollen from a flower, photosynthesis of plants, deer eating shrub leaves or lions eating the deer. Show A food chain shows how energy is transferred from one living organism to another via food. It is important for us to understand how the food chain works so that we know what are the important living organisms that make up the food chain and how the ecology is balanced. Photosynthesis is only the beginning of the food chain. There are many types of animals that will eat the products of the photosynthesis process. Examples are deer eating shrub leaves, rabbits eating carrots, or worms eating grass. When these animals eat these plant products, food energy and organic compounds are transferred from the plants to the animals. These animals are in turn eaten by other animals, again transferring energy and organic compounds from one animal to another. So for how many levels does this go on? To follow the food chain to its different levels and know how it works go to this site. The page also contains names and definitions of terms used to describe the 'players' in the food chain- producers, consumers, herbivores. You can also refer to the diagrammatic representations of food chains, food webs and ecological pyramids. A food chain describes how energy and nutrients move through an ecosystem. At the basic level there are plants that produce the energy, then it moves up to higher-level organisms like herbivores. After that when carnivores eat the herbivores, energy is transferred from one to the other. To understand how this happens visit the link. In the food chain, energy is transferred from one living organism through another in the form of food. There are primary producers, primary consumers, secondary consumers and decomposers- all part of the food chain. Follow this link for a good introduction to how food chains work. There are links to types of energy and also simple explanations to how photosynthesis is the starting point of the food chain. This site also tells us that because of our eating habits, we are in two food chains- marine and land. Plants that have photosynthesis are supplying us with the first product of the food chain. Not only that, they are the source for oxygen, the food we eat, our clothes, and even our furniture, among other things. Plants also remove greenhouse gas from the air, provide habitat to many animals. Therefore we should understand the ecology of the environment with respect to plants. What is their number in terms of individuals (the population), and with respect to other living beings in the environment. Go to this page to see where plants are placed with respect to other living organisms. In typical grassland, for example, the plants outnumber all other levels in the pyramid combined. However in the forests, other living organisms compete for space with plants. But a balance is maintained in the ecosystem. There may be special relationships that have evolved within the community in which one particular species grows in obligate association with one other particular species, upon which still others depend. This site explores such relationships. Name one major difference between a plant and an animal. There are many differences, but
in terms of energy, it all starts with sunlight. Plants absorb the energy from the sun and turn it into food. You can sit in the sun for hours and hours. You will feel warm, but you're not going to absorb any energy. You have to eat to obtain your energy. Living organisms
obtain chemical energy in one of two ways. Autotrophs, shown in Figure below, store chemical energy in carbohydrate food molecules they build themselves. Food is chemical energy stored in organic molecules. Food provides both the energy to do work and the carbon
to build bodies. Because most autotrophs transform sunlight to make food, we call the process they use photosynthesis. Only three groups of organisms - plants, algae, and some bacteria - are capable of this life-giving energy transformation. Autotrophs make food for their own use, but they make enough to support other life as well. Almost all other organisms depend absolutely on these three groups for the food they produce. The producers, as autotrophs are also
known, begin food chains which feed all life. Food chains will be discussed in the "Food Chains and Food Webs" concept. Heterotrophs cannot make their own food, so they must eat or absorb it. For this reason, heterotrophs are also known as consumers. Consumers include all animals and fungi
and many protists and bacteria. They may consume autotrophs or other heterotrophs or organic molecules from other organisms. Heterotrophs show great diversity and may appear far more fascinating than producers. But heterotrophs are limited by our utter dependence on those autotrophs that originally made our food. If plants, algae, and autotrophic bacteria vanished from earth,
animals, fungi, and other heterotrophs would soon disappear as well. All life requires a constant input of energy. Only autotrophs can transform that ultimate, solar source into the chemical energy in food that powers life, as shown in Figure below. Photosynthetic autotrophs, which make food using the energy in sunlight, include (a) plants, (b) algae, and (c) certain bacteria. Photosynthesis provides over 99 percent of the energy for life on earth. A much smaller group of autotrophs - mostly bacteria in dark or
low-oxygen environments - produce food using the chemical energy stored in inorganic molecules such as hydrogen sulfide, ammonia, or methane. While photosynthesis transforms light energy to chemical energy, this alternate method of making food transfers chemical energy from inorganic to organic molecules. It is therefore called chemosynthesis, and is characteristic of the tubeworms shown in Figure
below. Some of the most recently discovered chemosynthetic bacteria inhabit deep ocean hot water vents or “black smokers.” There, they use the energy in gases from the Earth’s interior to produce food for a variety of unique
heterotrophs: giant tube worms, blind shrimp, giant white crabs, and armored snails. Some scientists think that chemosynthesis may support life below the surface of Mars, Jupiter's moon, Europa, and other planets as well. Ecosystems based on chemosynthesis may seem rare and exotic, but they too illustrate the absolute dependence of heterotrophs on autotrophs for food.  A food chain shows how energy and matter flow from producers to consumers. Matter is recycled, but energy must keep flowing into the system. Where does this energy come from? Though this food chains "ends" with decomposers, do decomposers, in fact, digest matter from each level of the food chain? (see the "Flow of Energy" concept.)
Tubeworms deep in the Galapagos Rift get their energy from chemosynthetic bacteria living within their tissues. No digestive systems needed! Making and Using FoodThe flow of energy through living organisms begins with photosynthesis. This process stores energy from sunlight in the chemical bonds of glucose. By breaking the chemical bonds in glucose, cells release the stored energy and make the ATP they need. The process in which glucose is broken down and ATP is made is called cellular respiration. Photosynthesis and cellular respiration are like two sides of the same coin. This is apparent from Figure below. The products of one process are the reactants of the other. Together, the two processes store and release energy in living organisms. The two processes also work together to recycle oxygen in Earth’s atmosphere. This diagram compares and contrasts photosynthesis and cellular respiration. It also shows how the two processes are related. PhotosynthesisPhotosynthesis is often considered to be the single most important life process on Earth. It changes light energy into chemical energy and also releases oxygen. Without photosynthesis, there would be no oxygen in the atmosphere. Photosynthesis involves many chemical reactions, but they can be summed up in a single chemical equation: 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2. Photosynthetic autotrophs capture light energy from the sun and absorb carbon dioxide and water from their environment. Using the light energy, they combine the reactants to produce glucose and oxygen, which is a waste product. They store the glucose, usually as starch, and they release the oxygen into the atmosphere. Cellular RespirationCellular respiration actually “burns” glucose for energy. However, it doesn’t produce light or intense heat as some other types of burning do. This is because it releases the energy in glucose slowly, in many small steps. It uses the energy that is released to form molecules of ATP. Cellular respiration involves many chemical reactions, which can be summed up with this chemical equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + Chemical Energy (in ATP) Cellular respiration occurs in the cells of all living things. It takes place in the cells of both autotrophs and heterotrophs. All of them burn glucose to form ATP. Summary
Explore MoreUse this resource to answer the questions that follow.
Review
What do you call the group of organisms that eat?There are three groups of consumers. Animals that eat only plants are called herbivores (or primary consumers). Animals that eat other animals are called carnivores. Carnivores that eat herbivores are called secondary consumers, and carnivores that eat other carnivores are called tertiary consumers.
How do other organisms get their food?Autotrophic organisms make their own food by a process called photosynthesis. Green plants, for example, manufacture sugar and starch from carbon dioxide and water using the energy of sunlight to drive the necessary chemical reactions. Heterotrophic organisms obtain their food from the bodies of other organisms.
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