Name: _____________________________________ Period: _______
Food chains, Food Webs, and Symbiosis Questions
1. a) Draw arrows between the organisms to show how energy moves through this food chain. Write
producer (autotroph), herbivore (heterotroph), or carnivore (heterotroph), under each organism.
Then write down the number that corresponds with the trophic level of the organism.
b) Describe how energy flows through this food chain.
c) What do ecologists mean when they say that sharks indirectly depend on krill for their
survival?
d) What would happen to this food chain if a disturbance caused a serious decline in the
shark population?
e) If there is 25,000 kcal available at the level of the phytoplankton, how many kcal are
available to
i. The zooplankton ____________________
ii. The fish ____________________
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Name: _____________________________________ Period: _______
iii. The squid ____________________
iv. The shark ____________________
2. Two examples of producers in an aquatic ecosystem are ________________________________
and ____________________________
3. What do arrows represent in a food chain/web?
4. Which type of organism is always at the base of every ecological pyramid and food chain/web?
5. Which group of organisms is always found at the base of a food chain or web? Explain why.
6. Examine the picture below and answer the following questions
b) What type of organism is missing from this food web and every food chain/web?
_____________
c) What is the tertiary consumer? ____________________________________
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Name: _____________________________________ Period: _______
d) What is the primary producer? ____________________________________
e) If there are 2,000 calories of energy available for the starfish, how many calories of energy
are available to the mussels? _______________ and human? _________
f) If the zooplankton population decreased significantly, explain how that would affect its
predator and its prey. How would it also affect octopus?
7. Which of the following statements is true about matter and energy?
b) Matter is not recycled; energy is recycled
c) Matter is recycled; energy is not recycled
d) Both matter and energy are recycled
e) Neither matter nor energy are recycled
8. Compared to the osprey, the perch has
b) 1/100 the energy available
d. 20x more energy available
c) 10x more energy available
e. 100x more energy available
d) 1/10 the energy available
9. Ants are known to protect, or "tend" aphids from predators, and in return receive some nutrients
from the aphids. This relationship is an example of this type of symbiosis:
________________________________
10. Sea anemones contain a venom that is used to sting and paralyze their prey. The clownfish
contains an enzyme in their scales that makes them immune to the venom. This allows them to
freely live in the sea anemone without being harmed. This is an example of what type of symbiotic
relationship? ______________________________
11. Why is the transfer of energy in a food chain usually only about 10 percent efficient?
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Name: _____________________________________ Period: _______
12. Write True or False on the line provided.
__ a. Primary consumers always make up the first trophic level in a food web.
__ b. On average, about 50 percent of the energy available within one trophic level is
transferred to the next trophic level.
__ d. The more levels that exist between a producer and a given consumer, the larger the
percentage of the original energy from producers is available to that consumer.
13. Use this diagram to answer the following questions. The diagram shows the typical impact of a
chemical pollutant in an aquatic ecosystem.
a) Name and describe the process that this diagram is illustrating.
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Name: _____________________________________ Period: _______
14) What is the other way of saying "Biological Magnification?
a. Biological build-up
b. Biomultiplication
c. Bioaccumulation
d. Biological enlargenment
15) Which ends up with the most posions/chemicals due to biological magnification?
a. Producers
b. Organisms of a high trophic level
c. Organisms of a low trophic level
d. Tertiary consumers
16) Review the image and answer the following questions.
17) Why are birds shown at the top of this food chain as being susceptible to high concentrations of DDT?
A. Birds are at the top of every aquatic food chain.
B. Birds consume fish at all levels of aquatic food chains.
C. DDT made the eggshells of predatory birds very fragile, and their population sizes plummeted,
leading to a ban of DDT in the United States.
D. There is no significance to showing birds at the top of this food chain.
18) . Why does DDT magnify within food chains when certain other chemicals do not?
A. DDT is more toxic.
B. DDT is stored in animal fat and is not readily eliminated from the body.
C. DDT is now present in great quantities in most natural habitats.
D. All of these are correct.
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Name: _____________________________________ Period: _______
19) Selenium is a heavy metal that can undergo biomagnification. In which of the organisms in the food
chain below would you expect to find the highest concentration of selenium?
A. carp
B. large insect larva
C. pondweed
D. small insect larva
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