BBC Bitesize - GCSE Biology (Single Science) - Classification - Revision 1
Eg. vegetation zones such as the Tundra, Desert & Rainforests. Ecosystem: a) Biota: the living organisms - all plant & animal species E.g. fungi, bacteria, insects, worms and others. (a) mutually beneficial to both species, For example , relationship between flowers and insects is a mutually supportive relationship, or . Living things such as plants, animals, fungi, and bacteria. Ecological relationship between members of at least two different species that live in direct contact. biotic, Factors are living things such as plants animals, fungi, and bacteria Food chain, is a sequence tat links species by their feeding relationships. Herbivore.
So what do these interactions look like in an ecosystem? One category of interactions describes the different ways organisms obtain their food and energy. Some organisms can make their own food, and other organisms have to get their food by eating other organisms. An organism that must obtain their nutrients by eating consuming other organisms is called a consumer, or a heterotroph. While there are a lot of fancy words related to the sciences, one of the great things is that many of them are based on Latin or Greek roots.
They then use the energy and materials in that food to grow, reproduce and carry out all of their life activities. All animals, all fungi, and some kinds of bacteria are heterotrophs and consumers. Some consumers are predators; they hunt, catch, kill, and eat other animals, the prey.
The prey animal tries to avoid being eaten by hiding, fleeing, or defending itself using various adaptations and strategies. These could be the camouflage of an octopus or a fawn, the fast speed of a jackrabbit or impala, or the sting of a bee or spines of a sea urchin.
If the prey is not successful, it becomes a meal and energy source for the predator. If the prey is successful and eludes its predator, the predator must expend precious energy to continue the hunt elsewhere. Predators can also be prey, depending on what part of the food chain you are looking at. For example, a trout acts as a predator when it eats insects, but it is prey when it is eaten by a bear.
It all depends on the specific details of the interaction. Ecologists use other specific names that describe what type of food a consumer eats: Omnivores eat both animals and plants. Once again, knowing the Latin root helps a lot: For example, an insectivore is a carnivore that eats insects, and a frugivore is an herbivore that eats fruit. This may seem like a lot of terminology, but it helps scientists communicate and immediately understand a lot about a particular type of organism by using the precise terms.
Not all organisms need to eat others for food and energy. Some organisms have the amazing ability to make produce their own energy-rich food molecules from sunlight and simple chemicals. Producers are Autotrophic Organisms. The most conspicuous group of autotrophs are the photolithoautotrophs, organisms such as algae and flowering plants that have cells containing chlorophyll and are thus capable of fixing light energy "photo-" to build complex organic substances from simple inorganic substances "litho-".
In the next chapter we are going to study the energetics of this process; now, we are mostly interested in how producers "create" organic matter utilizing energy and inorganic matter. The organic compounds that are created may be used structurally within the organism or may be latter broken down into inorganic matter and energy extracted by the process. Consumers are [ Heterotrophic Organisms ], which are also termed macroconsumers. A simple definition of a heterotrophic organism is a species that is dependent on organic matter for food.
Decomposers are heterotrophic organisms. These are also termed microconsumers, saprobes, or saprophytes. Decomposers are scavengers that break down dead plants and animals. Decomposers are vital to the food web because they break down and recycle nutrients back into the soil. These nutrients are then used by producers to sustain life.
Without the enzymes that decomposers provide to breakdown organic material into inorganic material, phosphorous P and nitrogen NProducers would eventually die out and the main part of food webs would cease to exist and therefore life would cease to exist. Decomposers recycle material but they do not recycle energy. Solar irradiation still provides the energy that drives the life cycle. A foodweb of rainforest organisms Decomposition is a natural process but decomposers speed up the process of decomposition.
Bacteria, fungi and actinomycetes are three main types of decomposers. They can eat anything from dead trees, dead animals and oil slicks on the surface of the ocean. Fungi and actinomycetes work on harder substances like cellulose, bark, paper and stems. These decomposers usually only work to a certain stage in decomposition then bacteria will finish the process, similar to primary and secondary succession.
A study conducted in a California river by Mary Power showed the impact that fish had on the river food wed. The main fish studied in the experiment were the steelhead and roach, these fish at a juvenile stage consume insects and fish fry, which consume chironomid larvae.
These larvae reduce the algae biomass in the river. She found that when the larger adult fish species were absent, smaller more abundant predators thrived and decrease the chironomid larvae population significantly, which allowed the algae biomass to increase.
This results in more cyanobacteria and diatoms to flourish on the algal turfs .
This study showed a good example of how consumers and producers interact, and also showed that when one trophic level is disrupted it has a domino effect on the other trophic levels involved in the food web. With Food Webs there are a few calculations that we can use to help us better understand the system. Chain Length is essentially the number of links between trophic levels. But when we calculate this we use the mean length. We can also calculate link density LD.
And finally we can calculate Web Connectance C. Food webs do pose some problems for ecological studies. Identifying trophic levels is very difficult in nature. Ecosystem boundaries are also tough to determine. Identifying all of the species in a community can be difficult.
Quantifying and identifying the strengths of interactions is hard. In most cases it is very hard to determine what the eliminating nutrients are.
Biological Magnification[ edit ] The focus of this chapter is trophic levels and nutrient transfer between trophic levels and the food webs. Not all transfers between trophic levels are positive. Biological Magnification is the tendency of pollutants to concentrate in successive trophic levels.
The pollutants are usually toxic and cause death to the organism. The first step in Biomagnification is when a producer takes up nutrients in the soil that it stores by accident as an essential nutrient.
Producers will try to store massive amounts of nutrients, when "mistaken" nutrients are absorbed, i. DDT and Mercury, The concentration levels in the producers are greater than the levels in the surrounding environment. When the producer is eaten by the herbivore or omnivore the pollutants are transferred to the next trophic level. Since energy transfer between trophic levels is approximately ten percent, the next chain in the trophic level must try to consume large amounts of the previous trophic level to sustain life and the pollutant, once again, is concentrated in the next trophic level.
The pollutants, once absorbed, are stored in the bodies of the consumers. DDT and PCB's are fat soluble and when one trophic level is consumed by the other the fat moves from one consumer to the next. Water soluble pollutants usually cannot concentrate because they would easily dissolve in the organism.
Polluted water leaves an organism rather easily whereas fat does not leave the body. Three main criteria must be met for a pollutant to biomagnify: The pollutant must be long lived. The pollutant must be concentrated by the producers. The pollutant must be fat-soluble. Guild[ edit ] Species competing for the same resources in similar fashion are known as guilds. They are classified according to how they acquire their nutrients, their state of mobility, and their mode of feeding. Some examples of guilds are forbsgeophytes, graminoids, shrubs, trees and vines.
A guild is much more stable then a single species, since more than one species can balance out the system. In a study of feeding patterns on polychaetesFauchald and Jumars utilized feeding guilds as a method of generalization and determining phylogenetic relationships, indeed claiming that guilds were very useful in summarizing data into patterns .
In a study, a guild approach was used to evaluate the roles of foraging habitats and exposure timing, as well as tropic position on Mercury Hg bioaccumulation. Five species of waterbirds forming three distinct foraging guilds in the San Franciso Bay SFB estuary were used in this investigation. Also called Omnivores 3.
THE ECOSYSTEM: INTERRELATIONSHIPS BETWEEN
They are the final link in the food chain. Comprise of organisms that feed on dead matter and break it down to release chemical energy back into the soil for plants to re-use them. A food chain or food web comprises a sequence of organisms through which energy and nutrients are taken in and used up.
A food chain in a wet meadow could be: Food chains begin from producers to consumers and the major feeding levels are called Trophic Levels. Producers belong to the First Trophic Level. Primary consumers, whether feeding on living or dead producers feed from the Second Trophic Level. Organisms that feed on other consumers belong to the Third Tropic Level. Examples include ticks, fleas, mosquitoes, mistletoe plants and fungi. Plant and animal species compete over food, water, territorial space and mating with the opposite sex.