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Ecology

Learn about the key concepts in ecology, including habitat, niche, population, community, ecosystem, producer, consumer, food chains, food webs, trophic levels, and the nitrogen cycle.

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Ecology

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  1. Ecology

  2. Definitions • Habitat – The natural home or environment of an animal, plant, or other organism. Eg. Marine habitat • Niche – the relational position of species in an ecosystem to each other and how an organism or population responds to the distribution of resources and competitors

  3. Population – all the organisms of one particular species within a specified area at a particular time, sharing the same gene pool and more or less isolated from other populations of the same species. • Community – all of the populations of all of the different species within a specified area at a particular time.

  4. Ecosystem - all the organisms living in a particular area, as well as all the nonliving (abiotic), physical components of the environment with which the organisms interact, such as air, soil, water and sunlight. • Linked together by energy flow and cycling of nutrients. • Vary in size but always form a functional entity.

  5. Producer – an organism that makes its own organic nutrients, using energy from the sun, by photosynthesis.

  6. Consumer – an organism that gets its energy by feeding off another organism

  7. Food Chains and Food webs Food chain – chart showing the flow of energy from one organism to the next beginning with the producer.

  8. Food web – network of interconnected food chains showing the energy flow through part of an ecosystem

  9. Trophic Level – position of an organism in a food chain, food web or pyramid of biomass, numbers or energy. • Energy is lost from each trophic level as it is used by the organism for: • Respiration while the animal is alive • Excretion of waste products • The only energy passed on is what is in the biomass. About 10% of what it ate. • The higher one goes in the food chain the less energy available so most chains only have 5 trophic levels.

  10. Nitrogen cycle

  11. Nitrogen in several forms. • 78% of atmosphere is nitrogen gas. • But most not usable by life on Earth. • nitrogen is transformed into a form usable by plants. • In two ways:

  12. Nitrogen fixation Rhizobiumare bacteria established inside root nodules of legumes (peas, beans, clover, and soy), • N2 + 8 H+ + 8 e− → 2 NH3 + H2 • NH3 + H+ → NH4+, using enzyme nitrogenase • In return, the plant supplies the bacteria with carbohydrates, proteins, and oxygen

  13. Nitrosomonasoxidizes ammonia into nitrite  • Nitrobacteroxidizing nitrite to nitrate • Nitrates then absorbed by plants

  14. decomposing bacteria start ammonification, to convert plants and animals back into ammonia • anaerobic bacteria will convert them back into nitrogen gas, denitrification. • In watery soils, bacteria use nitrates and nitrogen gas is formed. 

  15. Nitrobacter Rhizobium Nitrosomonas

  16. Lightning, ultraviolet radiation and electrical equipment can fixate nitrogen. • Algae and other more complex plants use nitrates and ammonia created by nitrogen fixation. • Animals eat these plants and use the nitrates in their bodies. • The remains of dead plants and animals are decomposed, creating ammonia. • This ammonia is a turned back into nitrate by bacteria through a process called nitrification.

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