3

=FINDING THE ENERGY=

BY THE END OF THIS LESSON, YOU SHOULD BE ABLE TO EXPLAIN THE FOLLOWING CONCEPTS:
What are trophic levels and how are they arranged?

What is meant by the 10% rule?

What happens to the energy in an ecosystem?

What is the equation for photosynthesis and what does it mean?

What are calories and what's the difference between calories and kilocalories?

There are 8 sections in this lesson


 * 1. Before you begin, consider this: You will need to create your own discussion prompt by the end of this lesson**

then, post a response to someone elses question. Try your best to create quality questions: avoid the basics of "what is the definition of....." type questions.
 * in the discussion page at the top,[[image:uparrow.jpg width="46" height="47" caption="uparrow.jpg"]] create a question that can be answered from the content of this page.


 * 2. read the following information. Remember to take notes**

Photosynthesis is the process of assembling simple chemicals (carbon dioxide and water) into more complex chemicals called carbohydrates (sugars) in the presence of light. But what does that mean?

Well....the basic reaction looks like this: CO2+H2O+LIGHT=CARBOHYDRATES +O2.....in other words........carbon dioxide + water + light = carbohydrates + oxygen

where did the light come from for this reaction? The sun, of course!!

Organisms in an ecosystem can be organized into layers based on how they get their energy.

These layers are called **trophic** layers. trophic=food

The basic, or bottom layer, is made up of producers

All activities in an ecosystem rely on the energy brought into the ecosystem by the plants through **photosynthesis**

The amount of energy brought into the ecosystem is called **gross production**

It can be measured by determining the total amount of biomass.


 * Biomass** is simply the mass of the organisms, if they were dried out. Think of beef jerky. Yum!

The **net production** is the amount of energy available for the next trophic level to use.

Think of it like this; if you were to eat beef jerky, you get energy, but only the energy left over that the cow (before he was killed) didn't use for himself.

So how much energy is left for the next trophic level? Well, as a general rule, only 10% of the energy moves from one level to the next.

The trophic levels are often illustrated in the shape of a pyramid. There are two reasons for this:
 * 1) consumers at any level never eat all of the food available. For example, squirrels never eat all of the acorns from the oak tree. This is to guarantee there is some left over to replenish what is lost
 * 2) energy is removed (used) from the ecosystem at each level. This is because most of the energy taken in by an organism is used to run and maintain its body. Think of it like this; when cows eat grass, they don't think to themselves, "Gee, I better save some energy for when I'm turned into hamburger."

Let's take a look at an example:

If we have 1000kg of grass, how much rabbit would that feed?

If we remember the 10% rule, then we know that 10% of 1000kg is 100kg, so the answer is 100kg of rabbits can live off of 1000kg of grass.

Suppose we have coyotes who like to eat rabbits. How much coyote can live off of our 100kg of rabbit? (remember the 10% rule)

If you said 10kg, you are correct!

Now, last but not least, we have lions who like to eat coyotes. How much lion can live off of our 10kg of coyotes?

You should have said 1kg.

Be careful when you think about biomass and the 10% rule. 1kg of lion does not mean only 1 lion. It means 1kg of lion. That would be like gathering up the lions in the area and weighing them. 1kg= 2.2pounds. That means our 10kg of coyote (or 22pounds of coyote) will support less than one lion, because 1 lion weighs a lot more than 2.2 pounds, don't you agree?


 * 3. Watch This!**
 * take a look at this videothat talks about energy flow in the ecosystem: or click on the link below





4**. How does your body use that energy?** Click here to learn about Metabolism
 * you will learn how all this biomass talk applies to you
 * click on the link below. then click on brainpop. then type in "metabolism" in the search bar.
 * take the graded quiz at the end of the video
 * email the quiz results to grademytest@gmail.com

5**. Calories, Calories, Calories!**

The unit we use to measure heat energy is the calorie. One calorie is the amount of heat needed to raise 1cc of water 1degree Celsius.

calories is different from Calorie (notice the capital letter and the lower case letter).

You have heard of Calories in food, but what you did not realize is that the Calories you are counting are actually kilocalories, or food calories.

1 food calorie, or Calorie, or kilocalorie, is equal to 1000 calories (lower case letter).

Confused yet? Don't be. But the next time you're eating food from a box, can, or wrapper, turn it over to look at the calories. You'll notice calorie is spelled with a capital C.

Click here to learn more about calories. But remember to come back when your done!


 * 6. ...And the cycle goes on and on, or does it? Read here to find out!**

The Law of Conservation (saving) of Energy says that Energy is never created or destroyed, it only changes forms. So....

Solar (radiant) energy is transformed by plants into food energy.

Consumers, then, turn food energy into other forms of energy, like heat energy, mechanical energy, kinetic energy, potential energy.

But, once we use energy, we "lose" it. It is transformed, used, and moves on.

We lose most of our energy in the form of heat.

Matter, on the other hand, is recyclable!

Organisms are born, live and die. Once they die, their body is recycled back into the earth, and their elements (carbon, hydrogen, oxygen, nitrogen) are used again and again by other living things. Pretty cool, huh?

revisit this video clip:



(don't forget to post your discussion questions!)


 * 7. It's wikispaces again!**
 * yes, use your wikispaces information to return to wikispaces and create another wiki tab on your wiki page
 * the third page should demonstrate what you have learned about trophic levels and energy transfer
 * use your notes to help you create your wikispace page