Food Chains and Food Webs

Organisms get their energy from the sun. The ___________________, or __________________ (self-feeders) produce their own food by the process of ________________________. They turn sunlight energy, water, and carbon dioxide into glucose and oxygen that all other organisms must live off of. __________________________ eat the plants, and in turn are eaten by the ____________________. Sometimes these meat-eaters are eaten by a _______ ______________________. These are most often broken down by scavengers and decomposers when they die, but could be taken by other carnivores when they are young or weakened.

Please use the following organisms to fill out the food web graphic organizer.

1) Placed each of the producers at the 1st trophic level next to the sun.
2) Place an appropriate hervivore (1st order consumer) in place to eat the producer.
3) Place an appropriate carnivore (2nd order consumer) in place to eat the herbivore.
4) Place an appropriate top carnivore (tertiary consumer) in place to eat the carnivore.
5) If there is a 5th level, be sure to have an appropriate top carnivore eat the top carnivore.

6) Next you need to think of all the possible lines showing a food web. Here is where all the possible feeding relationships can now be shown with lines connecting each organism to multiple other animals and plants.

7) Please answer the questions that follow.

top carnivores
black gramma grass
Cooper's Hawks
(prey on smaller birds)
flowering brittlebush
cottontail rabbit
desert shrew
(insectivore rodent)
desert olive bush
black yellow
garden spider
cattle egret
(remove parasites from
large herbivores)
narrowleaf milkweed
milkweed butterfly
redtail hawks
golden yarrow
goldenrod beetle
canada goldenrod
black phoebe
great horned owl
(eat primarily sm mammals)
desert mariposa lily
box elder bug
deer tick
mtn lions
box elder tree
downy woodpecker
sharp-shinned hawk
(preys on birds)
blue palo verde tree
bumble bee
whiptail lizards

Questions (to be answered on your own paper). Write complete thoughts.:

1) Please compare and contrast energy flow through a food chain and a food web.

2) Which is the most realistic idea? Food chains or food webs? Explain.

3) Which will weigh the most? All the producers in a square mile or all the top carnivores in a square mile? Explain.

4) In the simulation run today, which trophic level (producer, herbivore, or carnivore) grew the most? Explain?

5) What are limits that are put on plants in the real world that would not allow them unlimited growth and access to sunlight (photons)?

6) How were calories used by the plants in this simulation?

7) Compare and contrast how herbivores and carnivores used calories in this simulation.

8) Please explain why food chains are most often short.

9) What would the consequences be if a lower trophic level passed all their calories on to a higher level?

10) Why did the video producers of the video Evolution and Extinction use the "house of cards" as an analogy for a food web?

11) How could not understanding the evolutionary past be a mistake that could lead to our early extinction (The average time for a species to exist on Earth is 2 million years. We've only been around for around 30 thousand years)?