1. 91. Which consumes energy from dead organisms?
A. the sun
B. producers and consumers
C. trees, grasses and shrubs
D. scavengers, fungi, and bacteria

2. 92. Which type of organism is BEST at fixing nitrogen?
A. bacteria
B. fungi
C. protists
D. animals

3. A. nitrogen B. oxygen C. sulfur D. water
93. Which molecule is necessary in order for respiration to occur in plants and animals?
A. nitrogen
B. oxygen
C. sulfur
D. water

4. A. digestion B. respiration C. decomposition D. photosynthesis
94. Which process do animals use to obtain nitrogen within their diets?
A. digestion
B. respiration
C. decomposition
D. photosynthesis

5. 95. Which BEST explains the role of plants in the carbon cycle?
A. Plants take in oxygen and release carbon dioxide.
B. Plants take in carbon dioxide released by other organisms.
C. Plants take in carbon dioxide and pass it directly to animals.

6. 96. What is the primary source of energy for producers?
A. the Sun
B. the atmosphere
C. the metabolism of glucose
D. the decomposition of organic matter

7. A. snakes B. viruses C. insects D. bacteria
97. Which organisms contribute the most to the decomposition of dead organisms?
A. snakes
B. viruses
C. insects
D. bacteria

8. 98. Which would be MOST affected by the absence of water?
A. the transfer of pollen between flowers
B. the metabolism of glucose during respiration
C. the production of glucose during photosynthesis
D. the release of waste products into the environment

9. A. evaporation B. condensation C. decomposition D. photosynthesis
99. How are the remains of living organisms cycled through the ecosystem?
A. evaporation
B. condensation
C. decomposition
D. photosynthesis

10. A. fungi B. plants C. animals D. bacteria
100. Which provides MOST of the carbon dioxide that algae need to make food?
A. fungi
B. plants
C. animals
D. bacteria

11. A. chlorine B. nitrogen C. hydrogen D. carbon dioxide
101. In a marine ecosystem, which gas is needed by algae to produce oxygen?
A. chlorine
B. nitrogen
C. hydrogen
D. carbon dioxide

12. A. fox --> grass --> rabbit B. grass --> fox --> rabbit
102. Which shows the correct flow of energy through this simple food chain?
A. fox --> grass --> rabbit
B. grass --> fox --> rabbit
C. grass --> rabbit --> fox
D. rabbit --> grass --> fox

13. 103. Which level of a food chain has the MOST energy?
A. decomposers
B. scavengers
C. consumers
D. producers

14. 104. How does the energy in each trophic level of an energy pyramid compare to the energy in the preceding level?
A. It has about 5% of the energy from the level below it.
B. It has about 10% of the energy from the level below it.
C. It has about 15% of the energy from the level below it.
D. It has about 20% of the energy from the level below it.

15. 105. Which factor would MOST LIKELY have a negative effect on the rate at which photosynthesis occurs in a plant?
A. a lack of water
B. a shortage of oxygen
C. an increase in temperature
D. an abundance of carbon dioxide