5.1 communities and ecosystems/ Yok

Essential Biology 5.1: Ecosystems & Communities 7/09/2011Student Name: Yok Kradsanaoh

Main Source - http://click4biology.info/c4b/5/eco5.1.htm#five

http://ecosystemsandbiomes.wordpress.com/2010/12/10/why-are-there-difficulties-in-classifying-organisms-into-different-trophic-levels/

1. Define the following terms:

Species: A group of organisms that can interbreed to produce fertile off-spring.

Habitat - A natural home or an environment of a living organism.

Population - All the living inhabitants of a certain area.

Community - A particular group of people living together in one place; prac-ticing one ownership.

Ecosystem - A biological community of organisms interacting and their physi-cal environment.

Ecology - The branch of biology that deals with the relations of organisms to one another and their physical surroundings.

Niche - A position or a role taken by a kind of organism in a community.

Biodiversity - The variety of life in the world on in a particular habitat or ecosystem.

Stephen Taylor Bandung International School http://sciencevideos.wordpress.com 1

Self-feeding

Organisms which produce their own food from organic molecules

Other source-feeding

Organisms which derive energy from other living organisms

Lives in or non-living organic matter, secreting digestive enzymes into it and absorbing digestive products.

Ingests non-living organic matter

Eat producersEat other consumers

Ingest organic matter which is living or recently killed

ChemosyntheisPhotosynthesis



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Trophic level - A group of organisms that occupy the same position in a food chain.

2. Complete the tree below with definitions and examples of each type of feeding strategy.

Distinguish between the feeding strategies at each level of the diagram.

3. Food chains represent the flow of energy and nutrients in a series of feeding relationships.

Give one example of a marine food chain (min. 4 organisms)

Seal > Cod > Krill > Diatoms

Give one example of a terrestrial food chain (min. 4 or-ganisms)

Peacock > Snake > Frog > Grasshopper




Give one other example of a food chain (min. 4 organisms)

osprey > bream > freshwater shrimp > phytoplankton

4. Describe what is meant by a food web.

-Shows how food chains are linked together into a more complex feeding

Number of advantages over food chains including

- Shows more complex interactions between species within a community/ecosystem

- More than one producer supporting a community

- One producer being a food source for many other primary consumers

- That a consumer may have many different food sources weather the same or different trophic levels

- That a consumer can be an omnivore, feeding as a primary consumer and as a consumer at higher trophic levels




5. The food web below shows some coral reef feeding relationships;

a. Identify species in the following trophic levels:

i. Producers Trophic level 1 (phytoplankton, algae)

ii. Primary consumers Trophic level 2 (sea-whip, parrotfish, turtles, marine inverte-brates)

iii. Secondary consumers Trophic level 3 ( reef sharks, snappers, gropers)

6. On a separate sheet, construct a freshwater food web based on the following information:

Organism Energy sourcesWater crowfoot Sunlight Cased caddisfly larva Micro-plants, algae, particles of dead plants and animalsDamselfly nymph Micro-plants, algae, particles of dead plants and animalsMayfly nymph Micro-plants, algae, particles of dead plants and animalsDragonfly Other adult insects and small fliesDuck All nymphs, all plants, snails, tadpoles, young frogsFreshwater Shrimp Particles of dead plants and animalsWater vole Plants Algae Sunlight




Otter Fish, frogs and newtsWater starwort SunlightPond snail Microplants, all water plants and algaeAlderfly nymph Micro-plants, algae, particles of dead plants and animalsPond skater Particles of dead plants and animalsFrog Mayfly, midge larvae, pond skater, caddisfly, small fliesTadpole Micro-plants, algaeMicro-plants SunlightGreat diving beetle Water flea, snails, tadpole, all nymphsBullhead fish Diving beetle, tadpole, all nymphs, water flea, snail, midge larvae

Adapted from: http://www.cornwallriversproject.org.uk/education/education_pack.htm

7. For the food web created above:

a. Identify organisms in each of the trophic levels.

b. Identify organisms that fit more than one trophic level.

c. Identify those which could be classed as detritivores

8. Suggest why it is sometimes difficult to classify organisms into trophic levels.

Not all organisms all under just one trophic level, some secondary consumers can also be tertiary con-sumers, and since there is this ambiguity, categorization of organisms can fall into a grey area.

An example would be human beings. It’s hard to classify them into one trophic level because Human be-ings can be primary, secondary, tertiary, and quaternary consumers because humans can choose what kind of diet they have. Vegetarians do not eat meat and therefore makes them primary consumers. So depending on dietary choices of each individual, one can be considered either a primary, secondary, ter-tiary or quaternary consumer.

9. Outline why numbers of organisms are smaller at higher trophic levels.



http://www.cornwallriversproject.org.uk/education/education_pack.htm


Thinking of trophic levels as a pyramid. A pyramid gets small the higher that you go. So when one organ-ism consumes another one in the lower trophic level, only about 10% of the energy transfers from one trophic level to the next. With a smaller amount of energy filtering through, there is a smaller capacity that the energy can maintain. For example, there are more wolves then there are small woodland crea-tures. The wolves can’t live off of the small amount of available prey, therefore several wolves will starve until there are fewer wolves than woodland creatures.

10. State the original source of energy for almost all communities.

The original source of energy starts with the sun, then plants. Then herbivores eat the plants, the carni-vores eat the herbivoes, vultures and humans eat plants, carnivores sometimes and then it is recycled by bacteria. It is stored in the tissue of the animals.

11. Explain how energy flows through a community, including why energy transfers are never 100% efficient.

-The transfer of energy from one trophic level to the next is not efficient

-Approximately 10-20% of the energy on one trophic level will be assimilated at the next higher trophic level

12. State the function of a pyramid of energy.

-The volume of one is 10% of the layer below

-It is this loss of energy which in part makes food chains rela-tively short

-In a tropic rainforest the trapping of energy is more efficient, therefore the food chains are longer, & webs are more com-plex.




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13. Give an example of a unit of measurement used in a pyramid of energy, giving a description of each component.

-The narrowing shape illustrates the gradual loss of energy progressing along the links of a food chain to high tropic levels

-The base of the pyramid is (Scale=energy/area/unit time e. g. Kj m-2 yr-1

-Unlike pyramids with of number (of organisms) a pyramid cannot inver due to the second law of thermodynamics,‘energy cannot be created nor destroyed’.

14. “Energy flows through an ecosystem, nutrients are recycled.”

Explain this statement with the aid of a flow chart. Include the roles of saprotrophic bacteria and fungi.

-Decomposition is a complex process and serves many functions including the formation of soil, the recycling of nutrients stored in the organic materials, and the reduction of high energy carbon com-pounds.

-Is also a biological process which begins with the secretion of extra cellular digestive enzymes

-The enzymes are produced by the saprophytic bacteria and fungi

-secretes the enzymes onto the dead organism

-hydrolyze the biological molecules of which dead organism is composed

-the hydrolyzed molecules of which dead organisms are composed

-Organic molecules are oxidized to release carbon dioxide back into the atmosphere

-oxidized to release carbon dioxide in for of nitrate, nitrate and ammonium.

-Oxidation of the organic compounds produces energy for the saprophyte but returns to carious forms of matter to the abiotic environment.




15. Outline three examples of cycles of inorganic nutrients. For each, outline the uses of the nutri-ents in living organisms, its method of transfer into and through the food chain and how it is re-turned to the inorganic nutrient pool.

a. Carbon

All organic compounds contain carbon and the most important sources of all inorganic carbon is carbon dioxide in the atmos-phere.

• carbon dioxide is taken up by autotrophic organisms during photosynthesis and the carbon is incorporated into carbohy-drates and other compounds , such as proteins and fats;

• consumers (heterotrophic organisms) feed on plants, and their bodies assimilate carbon compounds derived from the plants;

• all organisms, including plants, release carbon dioxide dur-ing respiration as a by product. (Fermentation releases of carbon dioxide);

• when autotrophic and heterotrophic organisms die or lose body parts such as leaves, carbon dioxide is released as a result of decomposition;

• combustion of dead animal and plant material also releases carbon dioxide;• under high pressures, dead plants and animals are carbonized, forming fossil-fuels, such as

coal and crude-oil. These release carbon dioxide during combustion.(http://www.bcb.uwc.ac.za/Sci_Ed/grade10/ecology/cycling/nutr.htm)

b. Nitrogen

Nitrogen is an element essential in all organisms, occurring in proteins and other nitrogenous compounds, e.g. nucleic acids. Although organisms live in nitrogen-rich environ-ments (78% of the atmosphere is nitrogen) the gaseous forms of nitrogen can only be used by certain organisms. Free nitrogen must first be fixed into a useable form.

• free nitrogen in the atmosphere is mainly fixed by two groups of bacteria, nl. Azotobacter and Clostridium. The nitrogen is then used to manufac-ture proteins in their bodies, when they die, their proteins are broken down by decomposers (mainly bacteria and other micro-organisms), and converted into ammonia (blue-green algae, cyanobacteria, can also be use free nitrogen from the atmosphere);



http://www.bcb.uwc.ac.za/Sci_Ed/grade10/ecology/cycling/nutr.htm


• during electrical changes in the atmosphere(e.g. lightning), free nitrogen is fixed (com-bined) finally forming nitrate;

• nitrates are taken up by plants which use them to manufacture proteins;• animals (herbivores) eat plants and convert plant proteins to animal proteins, while carni-

vores obtain their plant proteins by indirect means (by eating herbivores);• when plants and animals die, the proteins in their bodies are broken down into ammonia by

decomposers. The process is known as ammonification;• ammonia is converted to nitrites by nitrite bacteria (Nitrosomonas and Nitrosococcus). Ni-

trites are again converted to nitrates by nitrate bacteria (Nitrobacter )This process is known as nitrification;

• different types of bacteria are also able to break down nitrates, nitrites and ammonia which results in the release of nitrogen. This process is known as denitrification.

(http://www.bcb.uwc.ac.za/Sci_Ed/grade10/ecology/cycling/nutr.htm)

c. Calcium



http://www.bcb.uwc.ac.za/Sci_Ed/grade10/ecology/cycling/nutr.htm


Works Cited1. Taylor, Stephen. Communities and Ecosystems. Science Video Resources (presentation). [Online] October 2009. http://sciencevideos.wordpress.com/bis-ib-diploma-programme-biology/05-ecology-and-evolution/02-communities-ecosystems

2. Allott, Andrew. IB Study Guide: Biology for the IB Diploma. s.l. : Oxford University Press, 2007. 978-0-19-915143-1.



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5.1 communities and ecosystems/ Yok