Name: _____________________________________________________
Class: ________________
4.3 Matter and Energy Flow through Ecosystems Exam
PreAP 2016 - 2017
1. (7.5 B) Fungi, bacteria, and insects perform a special function in the ecosystem by breaking down
dead matter in order to help cycle nutrients back through an ecosystem. Which of the following
scenarios would be most likely if an ecosystem lost all of its decomposers?
A. The ecosystem would do very well without the bacteria making everything smell bad. Plants
would survive longer and more animals would be attracted to the area.
B. The ecosystem would immediately turn into a desert.
C. The ecosystem would have piles and piles of dead material and eventually producers would
die from lack of nutrients, then affecting the entire food web.
D. None of these
2. (7.5 B) The element carbon is so important to life on Earth, an entire branch of chemistry is
designed to study it, called Organic Chemistry. When decomposers in an ecosystem break down the
organic material of once living organisms, the element carbon is also released. Why are
decomposers important to the ecosystem?
A. They recycle nutrients and release stored energy from dead organisms into the ecosystem.
B. They photosynthesize and produce oxygen as a byproduct.
C. They provide a direct energy source for producers.
D. They help keep plant populations under control.
3. (7.5 B) When thinking about the importance of cycling nutrients through an ecosystem, what is a
major flaw in food web models as far as representing the cycling of nutrients?
A. Most food webs don’t show the connection and importance of decomposers playing a major
role in the cycling of nutrients.
B. There are way too many animals to keep track of in a food web.
C. They often leave out the Sun, the most important decomposer of all!
D. Top level consumers are often treated with much more importance than producers.
4. (7.5 B) Why can steam be observed in a large pile of mulch or compost material?
A. It retains the heat from the Sun when it sits out and releases that heat when the air around it
is cooler.
B. Those are usually the toxic chemicals being released into the atmosphere.
C. The steam is evidence of heat being released, which is a byproduct of decomposition that is
occurring in a pile of mulch or compost.
D. It is purely the gaseous aroma of cow poop.
5. (7.5C) Which of the following correctly shows how energy flows through a food chain?
A. snake  hummingbird  flower  Sun
B. Sun  flower  hummingbird  snake
C. Sun  hummingbird  snake  flower
D. flower  Sun  snake  hummingbird
6. (7.5 B) In looking at the squiggly, curvy arrows above, how does this food chain diagram relate to
what you know about the decaying of organic matter?
A. Just like when matter decays, energy is released as heat into the atmosphere during the
flow of energy in a food chain as well.
B. Seaweed is decomposing small fish successfully.
C. Small fish are considered decomposers that break down seaweed.
D. All of the arrows in the above diagram represent energy going to decomposers.
7. (7.5 C) Look at the picture provided. Which organism in this food chain is a producer?
A. Plant
B. Beetle
C. Catfish
D. Hawk
8. (7.5 C) Using the diagram above, which of the following changes in this ecosystem would most
likely result in an increase in energy available to the catfish population?
A. An increase in the number of beetles.
B. An increase in the number of hawks.
C. A decrease in the number of plants.
D. A decrease in the number of beetles.
9. (7.5 C) What role does a consumer play in a food chain?
A. An organism that provides energy to the Sun.
B. An organism that transforms the energy of the Sun to make food.
C. An organism that eats producers and/or consumers to obtain energy.
D. An organism that is at the beginning of the path of energy in an ecosystem.
10. (7.5 C) In the
desert food web shown
above, if most of the snakes in this ecosystem were killed off due to environmental poisons, what
would be the most immediate result?
A. The hawk population will increase.
B. There will be an increase in the number of tarantulas and ants.
C. There will be an increase in the number of producers.
D. There will be an increase in the number of rats.
11. (7.5 C) In the desert food web shown above, what do the arrows represent?
A. The arrows show the direction that energy flows through an ecosystem.
B. The arrows point towards the organism being eaten.
C. The arrows show what organisms live together in the ecosystem.
D. The arrows point towards other organisms that are in competition with each other for food
supply.
12. (7.5 C) Using the diagram above, which of the following correctly describes the amount of energy
available at A and B in the diagram above?
A. A has the most amount of energy. B has the least amount of energy.
B. A has the least amount of energy. B has the most amount of energy.
C. A and B have the same amount of energy.
D. A and B have an endless supply of energy.
13. (7.5 C) If only 10% of the available energy is passed on at each stage in a food chain or web,
what happens to the other 90%?
A. It is destroyed.
B. It is all released as heat.
C. It is all stored as chemical energy. Until it is eaten, then it is all passed on to the consumer.
D. Some of it was used as mechanical energy and some was released into the atmosphere as
heat.
14. (7.5 C) Which of the following statements is most accurate regarding the food chain in the
diagram above?
A. 90% of the energy is lost to other forms as it moves from the bird to the coyote.
B. 10% of the energy is gained as it moves from the cricket to the grass.
C. 10% of the energy is lost as it moves from the grass to the cricket.
D. 90% of the energy is gained as it moves from the cricket to the bird.
15. (7.5 C) Models are used to represent situations in real life. All models have limitations. Some
models are more useful than others. Which of the following statements is most accurate when
comparing food chains and webs?
A. Food webs are essentially the same as food chains, therefore they both have the same
limitations.
B. Food webs better represent an ecosystem because they show multiple relationships
between a greater variety of organisms in an ecosystem, whereas food chains simply show a
direct relationship between producers and consumers.
C. Food chains better represent an ecosystem because they show multiple relationships
between a greater variety of organisms in an ecosystem, whereas food webs simply show a
direct relationship between producers and consumers.
D. Food webs and chains have no limitations.
16. (7.6 B) Many processes occur in the digestive system. Which process is best classified as a
physical change?
A.
B.
C.
D.
Saliva converting the starch molecules in cracker into simple sugars.
Digestive enzymes breaking down proteins into smaller fragments.
Bacteria converting lactose into simple sugars in the intestines.
Teeth grinding an almond into smaller pieces in the mouth.
17. (7.6 A) Four students were given a list of compounds and asked to identify which ones are
organic.
Formula
Student 1
CaO
Organic
C₂ H₄ (OH)₂
Organic
Ca(OH)₂
Organic
CH₄
Student 2
Student 3
Organic
Organic
Organic
Organic
Organic
Organic
Organic
NaCl
C₃ H₈
Student 4
Organic
Organic
Which student correctly identified the organic compounds in this list?
A.
B.
C.
D.
Student 1
Student 2
Student 3
Student 4
18. (7.12 D) Which table correctly describes the functions of the cell structures listed?
19. (7.12 B) Which table best shows the major functions of the circulatory, respiratory, digestive, and
endocrine systems?
20. (7.12 F) In the 1800 two scientists, Theodor Schwann and Matthias Schleiden, studied different
types of organisms. After many years of studying a great variety of organisms, they drew similar but
independent conclusions about their observations.
What statement was developed most directly from these conclusions and is part of the modern cell
theory?
A.
B.
C.
D.
The functions of living things occur in cells.
Cells exist only in multicellular organisms.
Living things are composed of cells.
Cells contain hereditary information.