Science 10
Assignment: Oh, What a Tangled Web We Weave
Name - ________________________________________________
Goals:
1.
2.
3.
4.
Identify the trophic levels of organisms in a food chain.
Predict changes in food chains.
Determine what various animals eat in a number of food chains.
Build two food webs.
Materials:
colored pencils: red, blue, green and yellow
Procedure:
Part I – Trophic Levels
A. For the food chain below, identify the:
grass
grasshopper
frog
snake
a) producer: _________________________________ (1)
b) primary (1st) consumer: ________________________________ (1)
c) secondary (2nd) consumer: _________________________________ (1)
d) tertiary (3rd) consumer: ________________________________ (1)
e) quarternary (4th) consumer: ______________________________ (1)
f) herbivore: ______________________________ (1)
g) first carnivore: ________________________________ (1)
h) top carnivore: ________________________________ (1)
eagle
B. Consider a food chain that is common in New Brunswick: (5)
sapling
deer
wolf
a) If the deer population increases, what will happen to:
i) the sapling population? increase or decrease
ii) the wolf population? increase or decrease
b) The changes in the sapling and wolf population will cause a change in the number of deer.
What happens to the deer population as a result? increase or decrease
c) As a result of the change in (b) what will now happen to:
i) the sapling population? increase or decrease
ii) the wolf population? increase or decrease
Part II - Examining Food Chains
A. Study the food chains listed below.
B. Complete the table on the next page. “X” all the organisms that each animal listed on the left side eats.
(13)
plants  land snail  mouse  raccoon
plants  sparrow  hawk
plants  rabbit  fox
plants  mouse  fox
plants  earthworm  robin  snake
plants  raccoon  fox
plants  rabbit  snake
plants  cricket  robin  fox
plants  earthworm  snake  hawk  fox
plants  rabbit  hawk
plants  small insects  mouse  owl
plants  rabbit  owl  fox
plants  cricket  mouse  hawk
plants  mouse  snake  owl
Food in an Ecosystem
Living Things the Forest Animals Eat
Sparrow
Snake
Robin
Raccoon
Rabbit
Plants
Owl
Mouse
Land snail
Small
Insects
Hawk
Earthworm
Cricket
Animals in a
Forest
Ecosystem
Cricket
Earthworm
Fox
Hawk
Small
Insects
Land snail
Mouse
Owl
Rabbit
Raccoon
Robin
Snake
Sparrow
Part III: Building Food Webs
A. Use the food chains in Part II to build a food web. The food web has been started for you on the next
page. Draw an arrow from each living thing to each thing that eats it. The first arrow in any food
chain (between producer and primary consumer) should be green, the second (between primary
consumer and secondary consumer) should be blue, the third (between secondary and tertiary
consumer) should be red and the fourth should be orange. Draw your lines neatly. This will make
your food web easier to read when you’re finished. (14)
earthworm
robin
snake
cricket
mouse
rabbit
plants
fox
owl
Food Web
small insects
sparrow
hawk
land snail
raccoon
B. Use the food chains provided in Part II and the food web you drew in Part III to answer the questions
below:
1. In how many food chains do the following animals appear? (6)
hawk _____
owl _____
earthworm _____
snake _____
fox _____
small insects _____
2. In how many food chains do plants appear? _______ (1)
3. List the organism in this forest ecosystem that is a producer. (1) _________________
4. List the organisms that are only primary consumers. (6) _____________________________________
___________________________________________________________________________________
5. What is another name for an animal that is only a primary consumer? (1) _______________________
6. Name the animal that is only a secondary consumer. (1) ___________________________________
7. What is another name for an animal that is only a secondary consumer? (1) ____________________
8. List the consumers that are omnivores. (2) ________________________________________________
9. Describe how 3 animals might be affected if owls were removed from the food chain. (1) ___________
___________________________________________________________________________________
___________________________________________________________________________________
10. Which organism in this food web has the greatest influence on the ecosystem? Justify your answer.
(1)
__________________________________________________________________________________
__________________________________________________________________________________