Dissolved Oxygen Quiz

Use the information you've learned about dissolved oxygen to answer the following ten multiple-choice questions. Take a deep breath and good luck!

1. What percent of the atmosphere we breathe is composed of oxygen gas?
   1. 78%
   2. 21%
   3. .03%
   4. 50%

2. Trace amounts of dissolved oxygen are measured in...
   1. percent
   2. mg/L
   3. grams
   4. mL

3. Oxygen is an essential element for...
   1. photosynthesis
   2. protein synthesis
   3. cellular respiration
   4. bones and teeth

4. High dissolved oxygen levels in a river indicate...
   1. low flow rates
   2. high turbidity
   3. excessive aquatic plants and/or algal blooms
   4. better water quality

5. An acceptable level of dissolved oxygen (mg/L) for cold water trout is...
   1. 2-4
   2. 5-7
   3. 7-9
   4. 11-15

6. High dissolved oxygen levels can result from...
   1. mixing and splashing
   2. the decay of dead animal and plant matter
   3. warm water discharge from wastewater and power plants
   4. excessive nutrients that increase aquatic plant and algae growth

7. Low dissolved oxygen levels can result from...
   1. mid-day photosynthesis
   2. run-off from cattle feedlots
   3. keeping trees along stream banks
   4. faster river velocities

8. One effect of low oxygen concentrations is...
   1. water levels drop
   2. temperature increases
   3. water becomes clear
   4. trout can't survive

9. During a dissolved oxygen test, the fuzzy orange material that gradually settles to the bottom of the round DO bottle is called a...
   1. scum
   2. floc
   3. film
   4. filtrate

10. The organism responsible for low oxygen levels during the decay of excessive plant and algae growth is...
    1. fish
    2. bacteria
    3. macroinvertebrates
    4. snails

Click here for the answers.