DATE:
NAME:
CHAPTER 1
CLASS:
Terrestrial and Aquatic Food
Chains & Food Webs
1. Are decomposers autotrophs or heterotrophs? Explain. (1 mark)
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2. Study the food web below and fill in the blanks in the questions below. (5 marks)
bass
wolf
trout
snake
crayfish
weasel
water spider
minnow
paramecium
algae
rabbit
wheat
field mouse
grass
a) The following organisms in the food web are producers:
_______________________________.
Producers are also known as ____________________________________________________.
b) A _________________ is an example of an aquatic herbivore in the food web.
A _________________ is an example of a terrestrial herbivore.
c) Water spiders are classified as ______________________ consumers and occupy the
__________ trophic level.
d) Field mice are classified as _________________consumers and occupy the ______________
trophic level.
e) The highest trophic level the bass could occupy is the __________trophic level.
f) The snake population in this community has been decreasing due to loss of habitat. As a
result, the weasel population will ___________ and the field mouse population will
____________.
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DATE:
CHAPTER 1
NAME:
CLASS:
Terrestrial and Aquatic Food
Chains & Food Webs
3. In the food chain shown on the previous page, the trout is over-fished and the population of this
species decreases drastically. Describe the effect this change have on at least three other species
found at the other trophic levels. (2 marks)
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4. Isle Royale is a small island located in Lake Superior. The island is home to a population of
wolves and moose that are held in a delicate balance with one another. In the past, this balance
has been maintained. However, the moose population is currently the lowest it has been in many
years. The island was home to only 385 moose in 2007, having fallen from 450 in 2006. The
moose’s primary predators are wolves. Foxes also feed on the moose carcasses if there is
anything remaining, along with grass-eating snowshoe hares. Insects such as ticks and
mosquitoes feed on moose blood. Moose themselves are primary consumers that eat a variety of
woody plant materials, including balsam fir and birch. Aquatic plants make up a large percentage
of the herbivore’s summer food resource.
a) Create a food web for Isle Royale that includes the 8 organisms underlined above. Use
arrows. Arrows should point in the same direction as energy flow. (4 marks)
b) List the trophic level of each organism. (3 marks)
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DATE:
CHAPTER 1
NAME:
CLASS:
Terrestrial and Aquatic Food
Chains & Food Webs
c) The wolf population on the island has also fallen from 30 to 21; however, the fox population
has remained stable. Explain these findings with reference to your food web. (2)
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5. Use a venn diagram or table to identify two major similarities and two major differences between
photosynthesis and chemosynthesis. (2 marks)
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DATE:
CHAPTER 1
NAME:
CLASS:
Terrestrial and Aquatic Food
Chains & Food Webs
6. One acre of prime agriculture land in Canada can produce either 3 tons of quality hard red wheat or
16 tons of corn silage (animal feed). A cow or a steer consumes on average 27 Kg (wet weight) of
that feed per day. An average animal is approximately 450 kg and has about 250 kg of meat after it
is butchered. Whole wheat on average has 3,390 calories per Kg of energy while beef (80% lean,
20% fat) has on average 2710 calories per Kg. Humans need on average 2400 calories of energy per
day.
a) How many people could a 2500 acre wheat field support for one year?
b) How many people could a 2500 acre field support for one year if the farmer grew animal feed on
2250 acres, reserved 250 acres for as many cattle as she could feed, and the people ate only the
beef?
c) Draw a pyramid of biomass for the corn à beef à human food chain. Use an average individual
human mass of 70kg.
d) List at least three assumptions that are made in this hypothetical scenario.
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