Energy Pyramids
Part one: The Process of Primary Production
The general term "production" is the combining of different types of matter into new
forms of matter. Remember: matter is neither created or destroyed, it only changes
forms. When a plant, otherwise known as a producer or autotroph, goes through
photosynthesis it takes carbon dioxide from the atmosphere and water from the ground
and combines them with the energy supplied from the sun to create glucose (sugar).
This energy is stored within the tissues of plants and is used by the plant to live and
grow when they break the chemical bonds that hold glucose together. You might recall
that chemical bonds are where chemical energy is found in food. Food itself is not
energy; energy is stored in the chemical bonds of matter that hold the molecules that
make food together. Without performing photosynthesis plants would die based on a
lack of chemical energy required for them to perform life processes.
Below are two pictures to help you understand photosynthesis in plants:
This is what you may remember one compound of glucose to
look like. Notice all of the chemical bonds that hold each
individual element, such as Carbon (C), Hydrogen (H) and
Molecules like hydroxide (OH) together to form sugar.
chemical bonds
Part 2: Primary (first-level/first order) Consumers
A primary consumer is any organism that eats (consumes) a producer. A rabbit is a strict
herbivore eating plants only. Primary consumers rely on the chemical bonds stored in
glucose molecules in plants for energy. Once consumed, the consumer breaks the
chemical bonds in the food during digestion and uses the energy for survival.
Additionally, the smaller, broken down molecules are sent to cells in their bodies to be
used for things like growth and reproduction. Remember: most plants reproduce by
creating a fruit that contains a significant amount of chemical energy and has a seed
inside. When the consumer eats the fruit they can transport the seed before excreting
it. The consumer benefits by gaining chemical energy and nutrients from the fruit, while
the plant has its seeds distributed throughout the ecosystem. The plant does not always
have to die, as a result of the consumer eating the fruit. However, at times, the plant
itself is consumed and does die. Only the digestible portions of the plant give off
chemical energy and the indigestible food is excreted into the ecosystem. For example:
Deer, a primary consumer, are known for eating corn from farmers’ fields. The outside
of corn is indigestible and as a result the chemical energy found within the molecules
that make up the outside of the kernel are not used by the deer—they are expelled,
undigested, into the ecosystem.
In the picture below, the bird is the primary consumer because it eats a producer (the
fruit).
Part 3: Secondary (second-level/second order) Consumers
Secondary consumers eat primary consumers. For example, a bear might eat a deer.
Since a deer eats only plants that makes it a primary consumer and if the bear eats the
deer then it’s a secondary consumer, as a result. We call animals that eat meat only
carnivores.
Which one of the organisms below is a secondary consumer?
Part 4: Tertiary (third-level/third order) Consumers and Beyond
Just as secondary consumers eat primary consumers, tertiary consumers eat secondary
consumers. Additionally, it is possible for a tertiary consumer to also eat a primary
consumer or even plants. In that case, that specific organism would be part of multiple
trophic levels.
Part 5: Decomposers
We've all seen -- and smelled -- the work of decomposers. Reach for an apple at the
bottom of the fruit bowl, or take a whiff of a garbage can, and you'll likely have a pretty
memorable tactile or olfactory experience. In other words—it will be squishy and smell
horrific.
Unfortunately, the memories we most often associate with decomposers involve rotting
food. The fact is, it's nearly impossible to recall the positive aspects of an organism
that's responsible for turning an apple into a handful of goo. But consider this: All of the
foods we eat -- including the foods that occasionally go bad before we get a chance to
eat them -- wouldn't exist if it weren't for the work of decomposers. Without this
diverse group of organisms breaking down nature's waste and making it usable again,
life on this planet might not exist -- at least not in the way we know and enjoy it.
Locked in the tissues of every plant and animal is a wealth of nutrients, including carbon,
nitrogen, and phosphorous. Living organisms require copious amounts of these and
other elements in order to synthesize the structural compounds that make up cells and
tissue and provide energy for life processes. These elements are an integral part of an
organism's tissues throughout its life.
When a plant or animal dies, those nutrients would remain forever locked in the dead
organism's tissues if it weren't for decomposers. Decomposers, including fungi, bacteria,
and invertebrates like earthworms, work to disassemble the cells and structures that
made up the living organism. In the process of breaking down dead plant and animal
tissue, decomposers not only gain energy to drive their own life processes, but release
nutrients back to the environment, where they can be used again by other organisms.
Source: http://www.teachersdomain.org/resource/tdc02.sci.life.oate.decompose/
PBS Resource
Part 6: Food Web
Use the information at the bottom of the food web worksheet to help correctly fill in the
blank boxes on the food web. Each organism will only fit in one.