Food Chain & Web Worksheet
Name:
Date:
Block:
Directions: Use the pictures below to answer the following questions.
Food Chain 1
Food Chain 2
Food Chain 3
1. Give 2 examples of producers in the food chains above.
2. Which of the three food chains is an aquatic food chain?
3. Which of the food chains would be found in Richmond, VA?
4. Name 2 herbivores in the food chains above.
5. What is the main source of all of the energy in all of these food chains (hint: it is NOT shown in the picture)?
6. For food chain 1: What is the secondary consumer?
the tertiary consumer?
decomposer?
7. Name an organism above that is a secondary consumer in one food chain but a primary consumer in another.
8. What type of consumer is the snake in food chain 2?
9. Give 2 examples of 4th level consumers.
10. What organism is common among ALL of the food chains? What is its function?
11. For food chain 3: What is the producer?
the primary consumer?
12. What does the direction of the arrow indicate?
the 4th level consumer?
1. How does a food web differ from a food chain?
2. Notice what type of food web is pictured above. Give a specific location in Richmond where this food web may be
found.
3. The winter of 2002 was unusually cold and killed off the majority of the insects (mayfly & stonefly). Will the
crayfish population increase or decrease (hint: look at the “common” animal between them)? Why?
4. From the food web above: name an omnivore, a herbivore and a carnivore.
5.
a. What would happen to the population of Stoneflies if the fish in this stream were over fished and gone?
b. If part a occurred, what would happen to the mayfly population?
6.
a. In the 1998 summer, there was a surge in the caddisfly population. How did this effect the algae?
b. How is the stonefly population affected by the surge in caddisflies?
c. Did the summer of 1999 have a large or small population of caddisflies? Why?
7. What organism will break down all of the dead matter in this food web?
8. In the fall of 2000, there was an overfishing of crayfish at this stream. How did the lack of crayfish affect the
submergent plants (look at the “common” animal between the two)?
9. What are the 2 producers in this food web?
Ecological Pyramid
1. Give the example for each of the following trophic levels: producer, primary consumer, secondary consumer,
tertiary consumer and 4th level consumer.
2. Which of the trophic levels ONLY has herbivores?
3. Which of the trophic levels (indicate name NOT number) has the most biomass? the least biomass?
4. What is the name of the law that states 90% of the energy from one trophic level is lost in transfer to the next
trophic level?
5. How much of the energy from the primary consumer reaches the tertiary consumer (assume the producer has
10,000 kcal)?
6. How much energy would the hawk receive if the grass had 15,000 kcal?
7. How much energy would the snake receive from the frog if the grasshopper had 1,250 kcal?
8. Which trophic level has the least number of species (give the name- not the number)?
9. How much energy would the grasshopper contain if the frog received 200 kcal?
10. How much energy would the hawk receive if the frog had 58 kcal?
11. How much energy did the grass have if the snake receives 18.3 kcal from the frog?
12. What is the herbivore in the pyramid above?
Biomagnification
Biomagnification is the process of passing chemicals, usually toxic, from one trophic level to the next. Chemicals
become concentrated in an organism’s body because an organism does not use the chemicals for energy and they are
not expelled as wastes- the chemicals just continually build up in the animal’s system.
The diagram above shows how pesticides contaminate zooplankton and can reach the highest trophic levels.
Zooplankton has 0.04 ppm (parts per million) but the bird has 25.0 ppm. The chemicals become magnified in the
higher trophic levels because these organisms eat a lot of the organisms below them in the food chain and consume
more of the pesticide.
1. How did the zooplankton become contaminated with pesticide? (hint: runoff)
2. Which of the trophic levels has 2.0 parts per million?
3. How much pesticide does a large fish consume if it eats 3 small fish?
4. How much pesticide does a small fish consume if it eats 3 zooplankton?
5. Why does the large fish have more pesticide in its body then a small fish? (use answers from 3 & 4 as evidence)
6. Which of the organisms has the most pesticide in their system?
7. Which organism is analogous to human beings? At which trophic level would we be?
8. How does biomagnification affect human beings?
9. How can human beings stop biomagnification?
10. Name another chemical other than pesticide that would be biomagnified.