EnergyEmily CordonIB Biology SL

http://www.248am.com

LightLight is the most important energy

source for almost every living thing. Plants absorb light through a

process called photosynthesis; carbon dioxide from air and water mix with light to form sugars. Light goes through the chloroplast of the cell and is converted to ATP.

http://www.biojourney.org

Trophic Levels of the Food ChainProducers – feed only off raw materials, like

water and sunlight (e.g. plants) Herbivores – a.k.a. primary consumers, feed

off of vegetation (e.g. sheep) Carnivores – a.k.a. secondary consumers,

feed off of herbivores (e.g. snakes) Carnivores – a.k.a. tertiary consumers, feed

off of other carnivores (e.g. birds of prey)

Energy Flow in the Food ChainEnergy flow in food chains was analyzed by H.T. Odum. Numbers in the flow chart are kilocalories per square

meter per year (kcal/m2/yr). Gross production – total calories acquired Net production – calories left after respiration Gross production is always higher than net production

because the organism uses the energy to stay alive, and some is also lost due to decay.

The values decrease as trophic levels go up. The ratio of the net production of a lower trophic level

compared to the next trophic level is called conversion efficiency.

The energy transformations between the trophic levels in the flow chart are never 100% correct.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/FoodChains.html

The Pyramid of Energy When the numbers of all the trophic levels

are stacked up, they make the shape of a pyramid because the total amount of energy decreases as the trophic levels increase.

For example, the net production of energy in spiders will be less than the insects they fed off of, and the insects’ energy will be less than the plants they fed off of.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/FoodChains.html

Grass

Fly

Spider

Bird http://www.netstate.com

http://www.markleyspest.com

http://www.mypetjawa.mu.nu

http://www.inkycircus.com

Nutrients Energy is used up by organisms, but

nutrients from light and other factors need to be recycled for the food chain to continue.

For example, in the previous food chain, the grass was eaten by the fly, the fly was eaten by the spider, and the spider was eaten by the bird. If there was nothing to eat the birds, and the birds just simply died, the dead bird’s nutrients need to be returned to the producers. The producers, like grass, absorb the dead bird’s nutrients so the food chain can continue.

Decomposers Saprotrophic bacteria and fungi, a.k.a.

decomposers, recycle nutrients by taking up carbon and other minerals from dead animals or other waste. After they store the minerals, they release them out into the ground so other plants can take them up.

http://www.diseaseproof.com

Bibliography van der Pluijim, Ben. "Introduction to Global Change."The Global

Change Program. Geoscience Education, 2006. Web. 13 Aug 2010. <http://www.globalchange.umich.edu/>.

Food Chains . N.p., 23 April 2010. Web. 13 Aug 2010. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/.  

"What do fungi do? ." FungiBank. N.p., n.d. Web. 13 Aug 2010. <http://www.fungibank.csiro.au/topic_3_2_1.htm>.

G. , Jayd. "Nutrients must be Recycled." Yahoo! Answers . Yahoo!, 2008. Web. 13 Aug 2010. <http://answers.yahoo.com/question/index?qid=20080913212336AAVyfMW>.