Energy Flow: Food Chains and Food Webs
The main source of energy for any ecosystem is the ________________. The ____________ energy is absorbed by ______________ and is converted into a potential energy source ­ a chemical potential energy source we call _____________. The name of this process is called ____________________________.
Scientists are always looking for patterns in nature. Many things about an ecosystem can be learned by looking at the patterns found in how organisms obtain their energy. Ecologists have devised food chains and food webs along with several descriptive terms to help understand an ecosystem. PHOTOSYNTHESIS
SUN
PLANTS
SUN'S
FOOD
Match the following term with the correct definition
Herbivore
Food Chain
Consumer
Decomposer
Food Web
Producer
eats meat
a community of organisms where there are several connected food chains a particular position occupied by a group of organisms in a food chain needs to eat other organisms to get energy
any organism that eats decaying organic matter Omnivore
Trophic Level
Carnivore
eats plants only
is able to make its own food through photosynthesis a community of organisms where each member is eaten in turn by another member eats both meat and plants
Food Chains
Food Chains show how organisms are linked together in an ecosystem based on what they ______________. The arrows in the food chain always point in the direction of the _______________ (ie. at the organism that is doing the eating).
In a food chain, labels are used to indicate characteristics of the organisms:
consumer (primary, secondary, tertiary and quaternary to show the order)
producer
herbivore
carnivore
omnivore
decomposer
Trophic levels are also labelled starting with the ____________ (first trophic level) and ending with the ____________________.
1
Label the following food chain
Role and Order
Types of organisms
plants
grasshoppers
small birds
hawks
Trophic Level
use the words in the banks
to label the food chain above
Role and order word bank
consumer secondary
producer primary
tertiary
decomposer
Types of organisms word bank
carnivore
omnivore
herbivore
carnivore
herbivore
Food Webs
In an ecosystem, many different ____________________ exist together creating a __________________________.
A __________________ shows the energy flow within an ecosystem starting with the ____________________ and ending with the __________________.
Label the following food web
Name 3 primary consumers.
What organisms are the top carnivores?
Draw one food chain that is within this food web.
What would happen if the herbivorous insects became extinct? Explain how this might effect other organisms in the food web.
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Food Chains and Food Webs Homework
Food Chains
Food chains show how organisms are connected through what they eat. The arrows in the chain always point in the direction the energy flows (towards the organism doing the eating). Using the organisms listed draw a food chain on the top of the next page. Your food chain should start with the producer and end with the organism that is not eaten by any other. Make sure your arrows are pointing in the direction of the energy flow. (leave space around your food chain to add labels)
1.
Grasshopper
Owl
Mole
Grass
Label the following on your food chain:
2.
producer(s)
consumer(s)
herbivore(s)
carnivore(s)
1st trophic level
2nd trophic level
3rd trophic level
4th trophic level
The first consumer in the food chain is known as the primary consumer. The second consumer is known as the secondary consumer. The third consumer is known as the tertiary consumer.
3.
Add the labels primary consumer, secondary consumer and tertiary consumer to your food chain as necessary.
4.
Remember that we, as humans, are consumers. Below each of the following meals, draw the food chain from producer to you. Label each food chain fully.
a.
A salmon fillet (The salmon eats herbivorous fish)
b.
A steak
c.
A bowl of plain rice (think about what rice comes from!)
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Food Webs
1. How many organisms form the longest food chain in the food web?
tree
2. Which organism in this food chain is hawk
owl
a) the top carnivore(s) (hint­ nothing eats the top carnivore)­ caterpillar
fox
b) a herbivore­ spider
c) a producer­ robin
mosquito
d) at the 2nd trophic level­ e) is a tertiary consumer­ deer
mouse
chipmunk
grasshopper
rabbit
grass
3. Write this food chain out (make sure your arrows point in the right direction!)
*Label your food chain fully­ use your notes as an example
4. Is there an omnivore in this food web? Explain your answer.
5. List all the primary consumers in this food web.
6. If all the squirrels were killed by a virus, what would happen to this food web? Would it remain sustainable? Explain your answer in detail.
7. If a pack of coyotes entered this ecosystem, how would it be impacted? Explain your answer in detail.
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Homework
Read the following description of the relationship between bees, clover flowers, dormice and humans. Answer the following questions using complete sentences.
Bees collect a sugar rich liquid, nectar, from clover flowers. They convert the nectar into honey which they use to feed their larvae and also as a winter food store. Humans and dormice are both fond of honey and dormice will also eat bee larvae in the honeycomb. Other animals such as cats and hawks will feed on dormice.
1) From this information draw a food chain involving four organisms starting from the clover flower. 2) In what form does energy enter this food chain? 3) Into which form is this energy converted by the clover plant? 4) Why do clover flowers produce nectar? 5) Give two reasons why the bees need to store honey for the winter. 6) If a beekeeper removes honey from the hive in autumn she will provide the bees with sugar solution. Suggest a reason for this. 5
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