Grade 8 Life Posttest
Select the best answer to each question.
____
1. The diagram below shows the flow of two gases between two organisms. One gas is a product of
photosynthesis and the other is a product of cellular respiration.
Which statement describes Product X?
A. It is carbon dioxide released by cellular respiration.
B. It is carbon dioxide released by photosynthesis.
C. It is oxygen released by cellular respiration.
D. It is oxygen released by photosynthesis.
____
2. Which statement about the products of photosynthesis is NOT true?
A. Some of the glucose is stored by the plant for later energy needs.
B. The oxygen is released through pores on the underside of the leaves.
C. The carbon dioxide is released through pores on the underside of leaves.
D. Some of the glucose is used to make structural materials such as cellulose.
____
3. The diagram below shows the processes of photosynthesis and cellular respiration.
What cellular structures are represented by B?
A. chloroplasts
B. lysosomes
C. mitochondria
D. ribosomes
____
4. Which of the following are reactants in cellular respiration as well as products of photosynthesis?
A. carbon dioxide and oxygen
B. carbon dioxide and water
C. glucose and oxygen
D. glucose and water
____
5. A freshwater marsh is a type of ecosystem. Grasses, fish, wading birds, frogs, and alligators live together in
freshwater marshes. Pieces of decaying material sink to the bottom of the marsh. In which of these places can
carbon be found in the marsh?
A.
B.
C.
D.
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in the atmosphere and water only
in living things only
in living things and decaying materials only
in the atmosphere, water, living things, and decaying materials
6. Robin studies this food chain.The sea grass passes carbon through the carbon cycle to the manatee.
What provides energy to the seagrass to make food?
A. air
B. carbon
C. Sun
D. water
____
7. Evan is studying a diagram of the carbon cycle. Which of the following will he learn from the diagram?
A. Carbon is lost among organisms and their environment.
B. Carbon moves only among living organisms and their environment.
C. Carbon usually moves from animals to plants rather than plants to animals.
D. Carbon is constantly being transferred among organisms and their environment.
____
8. A coral reef is damaged during a hurricane. The waves and currents move broken pieces of coral onto the
beach. What happened to the matter in the broken pieces of coral?
A.
B.
C.
D.
____
It is still part of the coral reef ecosystem.
It was removed from the environment.
It became part of the beach ecosystem.
It was lost due to the energy in the waves.
9. A snake eats a mouse. Then, an owl eats the snake. Which of the following statements about this system is
true?
A. Mass stays the same.
B. Mass increases as each animal adds mass.
C. Mass is lost as it moves from animal to animal.
D. Mass decreases because the animals do not consume all parts.
____ 10. Jacob draws this food chain.
What happens to energy as it moves through the food chain?
A. It is lost.
B. It is increased.
C. It is conserved.
D. It is unchanged.
Grade 8 Life Posttest
Answer Section
MULTIPLE CHOICE
1. ANS: D
A is incorrect because animals do not take in carbon dioxide.
B is incorrect because carbon dioxide is not a product of photosynthesis.
C is incorrect because oxygen is not a product of cellular respiration.
D is correct because oxygen is released by photosynthesis and taken in by animals.
STA: SC.8.L.18.1
2. ANS: D
A is incorrect because some glucose is stored by the plant for future use.
B is incorrect because oxygen is released through the stomata on the backs of the leaves.
C is correct becaue carbon dioxide is not a product of photosynthesis.
D is incorrect because some glucose is used to make structural elements like cellulose.
STA: SC.8.L.18.1
3. ANS: C
A is incorrect because cellular respiration does not take place in chloroplasts.
B is incorrect because lysosomes are not part of the processes shown here.
C is correct because cellular respiration takes place in the mitochondria.
D is incorrect because ribosomes are not part of the processes shown here.
STA: SC.8.L.18.2
4. ANS: C
A is incorrect because carbon dioxide is a reactant of photosynthesis and a product of cellular respiration.
B is incorrect because carbon dioxide and water are reactants of photosynthesis and products of cellular
respiration.
C is correct because glucose and oxygen are reactants of cellular respiration and products of photosynthesis.
D is incorrect because water is a reactant of photosynthesis and a product of cellular respiration.
STA: SC.8.L.18.2
5. ANS: D
• A is incorrect because living and decaying things also contain carbon.
• B is incorrect because the atmosphere, water and decaying materials also contain carbon.
• C is incorrect because the atmosphere and water also contain carbon.
• D is correct because carbon is found in all of these areas in the ecosystem.
STA: SC.8.L.18.3
6. ANS: C
A is incorrect because air provides carbon, not energy.
B is incorrect because carbon is not the original energy source.
C is correct because energy from the Sun allows the seagrass to make food.
D is incorrect because water provides hydrogen and oxygen, not energy.
STA: SC.8.L.18.3
7. ANS: D
A is incorrect because carbon is not lost, only transferred.
B is incorrect because carbon also moves from dead organisms and fossil fuels, which are non-living.
C is incorrect because the opposite is true.
D is correct because carbon is constantly moving.
STA: SC.8.L.18.3
8. ANS: C
• A is incorrect because the coral was moved to the beach, so its matter is no longer a part of the reef
ecosystem.
• B is incorrect because the coral pieces became part of the environment beyond the coral reef.
• C is correct because the coral was no longer part of the reef, but it did become part of the beach.
• D is incorrect because the energy in the waves moved the matter in the coral to the beach; it did not destroy
any of the matter.
STA: SC.8.L.18.4
9. ANS: A
A is correct because according to the Law of Conservation of Mass, mass in a system is conserved.
B is incorrect because although each animal adds mass when it eats, it equals the consumed animal.
C is incorrect because mass is conserved, not lost.
D is incorrect because a decrease in mass implies mass is lost, which is false.
STA: SC.8.L.18.4
10. ANS: C
A is incorrect because according to the Law of Conservation of Energy, energy is never lost.
B is incorrect because according to the Law of Conservation of Energy, energy can be changed to other
forms, but it will not increase.
C is correct because according to the Law of Conservation of Energy, energy is conserved.
D is incorrect because according to the Law of Conservation of Energy, energy is conserved, but can be
changed.
STA: SC.8.L.18.4