Ecosystem Pt 2 Of 2

Symbiotic Relationship ● Symbiosis – interaction between two species. Sometimes beneficial, sometimes harmful… There are a few types:

● Commensalism ● Mutualism ● Parasitism

Commensalism ● Commensalism - an association between two organisms in which one benefits and the other derives neither benefit nor harm.

Mutualism ● Mutualism - symbiosis that is beneficial to both organisms involved.

Parasitism ● Parasitism - one species, the parasite, benefits at the expense of the other, the host.

8.L.3.3 Explain how the flow of energy within food webs is interconnected with the cycling of matter (including water, nitrogen, carbon dioxide and oxygen).

Flow of energy ● What is the ultimate source of energy? ● The sun! The flow of energy through ecosystems can be described and illustrated in food chains, food webs, and pyramids (energy, number, and biomass).

● Food Pyramid

Food Chain ● Food chain – linear sequence of links in a food web starting from "producer" species (such as grass or trees) and ending at apex predator "decomposer" species (like grizzly bears or killer whales).

● Simple ● Why are there fewer organisms at the top of the food chain?

Food Web ● Food web - a system of interlocking and interdependent food chains.

● More complex ● Interconnected

Energy Pyramid (Trophic Pyramid) ● Energy Pyramid – graphical model of energy flow in a community. ● Producers are at the bottom because they are able to

transform the sun’s energy into a large amount of plant energy through photosynthesis. ● Animals that eat plants are at the next level (primary consumers). They reply on plants for their energy. ● Animals that eat primary consumers are next (secondary consumers). They reply on primary consumers for most of their energy. The energy level of this section of the pyramid is smaller because most of the energy at the primary consumer level is used for their life processes and transformed to heat before these animals are consumed. ● Animals that eat secondary consumers make up the next level (tertiary consumers). They reply on secondary consumers for most of their energy. This energy level of the pyramid is even smaller than the others.

Energy Pyramid ● How much energy is lost from one level to the next? ● 10 % of the original energy is left to feed the next level. 90 % of the available energy is used for life processes such as respiration, photosynthesis, and reproduction and transformed to heat energy before an organism is consumed.

● The amount of energy at each trophic level decreases as it moves through an ecosystem.

Cycling of Matter ● The flow of energy is interconnected with the cycling of matter.

● Matter, in the form of nutrients, also moves though the organisms at each level. But matter cannot be replenished like the energy from sunlight. The atoms of carbon, nitrogen, oxygen and other elements make up the bodies of organisms alive today are the same atoms that have been on Earth since life began.

● Matter is constantly recycled.

Cycling of Matter ● Flow of energy within food webs is interconnected with the cycling of matter including… ● Water ● Nitrogen ● Carbon Dioxide ● Oxygen

Cycling of Water

Cycling of Nitrogen ● Nitrogen cycle – how nitrogen moves between plants, animals, bacteria, the atmosphere, and soil in the ground. ● For nitrogen to be used by different life forms on Earth, it must change into different states. Nitrogen in the air, N2, nitrates (N03), nitrites (NO2), and ammonium (NH4). ● The most important part of the cycle is bacteria. Bacteria helps nitrogen change between states so it can be used.

● Fixation - Fixation is the first step in the process of making nitrogen usable by plants. Here bacteria change nitrogen into ammonium.

● Nitrification - This is the process by which ammonium gets changed into nitrates by bacteria. Nitrates are what the plants can then absorb.

● Assimilation - This is how plants get nitrogen. They absorb nitrates from the soil into their roots. Then the nitrogen gets used in amino acids, nucleic acids, and chlorophyll.

● Ammonification - This is part of the decaying process. When a plant or animal dies, decomposers like fungi and bacteria turn the nitrogen back into ammonium so it can reenter the nitrogen cycle.

● Denitrification - Extra nitrogen in the soil gets put back out into the air. There are special bacteria that perform this task as well.

Cycling of Carbon Dioxide ● Carbon Cycle – cycles describing the flow of essential elements from the environment to living organisms and back to the environment again.

● All living things are made of carbon. Carbon is also a part of the ocean, air, and even rocks.

● Because the Earth is a dynamic place, carbon does not stay still. It is on the move!

Oxygen Cycle ● Almost all living things need oxygen. They use this oxygen during the process of creating energy in living cells.

● Plants mark the beginning of the oxygen cycle. Plants are able to use the energy from the sun to convert carbon dioxide and water into carbohydrates and oxygen into a process called photosynthesis.

● Animals form the other half of the cycle, we breathe in O2 which we use to break carbohydrates down into energy in a process called respiration. CO2 produced during respiration is breathed out by animals into the air.

● http://northsaanich.sd63.bc.ca/pluginfile.php/6749/mod _resource/content/1/sp7_-_chapter_2.pdf