1.2 Nutrient Cycles and Energy Flowhttp://www.sciencesource2.ca/pgs/book9_unitA.php?chapter=n&type=5&search=Go

Here is a summary of what you will learn in this section;

• Nutrients move through ecosystems in cycles.• Energy enters ecosystems through photosynthesis, is

transferred through cellular respiration, and is eventually lost as heat.

• Producers, consumers, and decomposers are related through food webs and energy pyramids.

Key Terms

• nutrients• elements• nutrient cycle• reservoir• run­off• aquifers• nitrogen fixation• nitrogen­fixing bacteria• nitrifying bacteria• denitrifying bacteria• chlorophyll• photosynthesis• cellular respiration• producers• consumers

• primary consumer• secondary consumer• tertiary consumer• herbivores• carnivores• scavengers• omnivores• detritivores• organic matter• prey• decomposers• food chain• food web• energy pyramid

A Great Migration

At the end of each summer in Tanzania, Africa a great migration begins. Over 1 million wildebeests move across the Serengeti Plain in search of food. The desperation for food will cause them to risk their lives by crossing huge rivers. Drowning is not the only concern for these animals. Crocodiles wait hungrily for the wildebeests to enter the water.

All organisms need food to survive. Animals must eat other organisms to survive. Grass is eaten by wildebeest, the wildebeest are eaten by the crocodile. Grass and wildebeest are examples of food. Food contains nutrients. Nutrients are substances that an organism uses to build and repair the cells of its body.

Nutrient Cycles

The nutrients your body needs to survive include carbohydrates, fats and oils, proteins, vitamins and minerals. These nutrients are made of elements (substances that cannot be broken down into simpler substances).

A nutrient cycle describes the movement of a nutrient back and forth from the abiotic and biotic parts of the ecosystem. Sometimes these nutrients or matter can cycle between the biotic and abiotic parts of an ecosystem fairly quickly. Other times the matter can stay in one place for a long time (even millions of years!). Any place where matter accumulates is called a reservoir.

Nutrient Cycles

Most organisms are dependent on many different nutrients to survive and are therefore dependent on many nutrient cycles. The water, nitrogen and carbon cycle and are briefly described on p. 24 ­ 27.

Using the diagrams for the above nutrient cycles, draw a single pathway for each one. Where an arrow appears, the nutrient changes form. Give a brief description as to the cause of this change of form.

http://sites.ext.vt.edu/virtualfarm/flash_mov/nitrogencycleintro.swf

http://www.youtube.com/watch?v=w03iO_Yu9Xw&feature=related

Nitrogen Cycle

Nitrogen in Atmosphere(N2)

Atmospheric fixation(N02­)

Nitrate (N03­)

Denitrifying bacteria

Learning Checkpoint

• Complete # 1 ­ 4 on p. 27

Energy Flows Through Ecosystems

The vast majority of the energy in the Earth's ecosystems comes from the Sun. A small fraction of sunlight is absorbed by the leaves of plants which then convert that energy into chemical energy. Green plants contain the chemical chlorophyll.

Photosynthesis

Plants use chlorophyll to convert the energy in sunlight to chemical energy. This chemical reaction is called photosynthesis and can be represented by the following word equation;

carbon dioxide + water + sunlight ⇒glucose + oxygen

The glucose is used by the plant for food. The oxygen is released as a byproduct but is essential for many types of life on Earth.

http://www.youtube.com/watch?v=pdgkuT12e14

Cellular Respiration

Plants and animals need a continuous supply of energy for functions such as growth, repair of tissues and reproduction. This energy is obtained through the chemical process of cellular respiration where glucose reacts with oxygen and can be represented by the following word equation;

glucose + oxygen ⇒carbon dioxide + water + energy

Animals cannot carry out photosynthesis so they need to eat other organisms to get glucose (carbohydrates).

http://www.youtube.com/watch?v=nkRcdfmHqqI

http://www.youtube.com/watch?v=S5zX15HD8pk&feature=related

http://www.youtube.com/watch?v=n8LjpGnTWuU&feature=related

Learning Checkpoint

• Complete # 1 ­ 4 on p. 29

Producers and Consumers

Ecosystems have many different parts with many different organisms. Each organism occupies a niche. Ecologists have names for each of these niches. For example, plants carry out photosynthesis and provide the energy for all other organisms and are therefore called producers. Any organism that eats other organisms to obtain energy are called consumers. Food chains are a way of showing feeding relationships among organisms. Arrange the organisms below into a food chain and label them.

Define the following terms, giving an example for each;

• herbivore• carnivore• scavenger• omnivore• detritivore• organic matter• predator• prey• decomposer

Food Chains and Food Webs

Most consumers eat many different types of food. This creates more complicated feeding relationships than illustrated by a food chain and can be modelled with a food web. Which do you think is more realistic in an ecosystem?

Energy Pyramids

Energy pyramids are a form of graph that shows the amount of energy available in producers and consumers. Because every organism uses energy itself and the digestive systems are not very efficient, only a small percentage of energy is passed up the food chain/web.

Energy Flow video.htm

A6:Quick LabComparing Energy Pyramids

Practice Quiz

http://www.sciencesource2.ca/resources/hotpotato_quiz_09_01_2.htm

http://www.sciencesource2.ca/resources/xword_gr09_ch01_2/index.html