Environmental Science 20 Unit 3 review answer key

Environmental Science 20
Unit 3: Aquatic Ecosystems Review
Part A: Vocabulary
River Mouth
Metabolic rate
Benthic Zone
Euphotic Zone
River Source
Aphotic Zone
River Course
Littoral Zone
Biotic factors
Index Species
Keystone Species
Abiotic factors
Part B: Short Answer Questions
1. What are three important functions of wetlands? Filters absorbs and removes pollutants from water, control flooding
by absorbing extra water, provide home for large biodiversity
2. What is a coral reef made of? Why does it need sunlight to survive? Where is Coral Reefs usually found? Accumulated
skeletons of coral polyps. It has a mutualistic relationship with algae. Usually found along the shore, in shallow waters,
close to the equator.
3. What is a tide? What happens during high and low tide? When do they occur? Rise and fall of sea levels, low tide
water recedes away from the shore( occurs when water closest to the moon), high tide water comes into the shore
(occurs when water is farthest from moon)
4. What are geophysical properties and list 5 of these properties? Abiotic factors
Temperature, turbidity, speed, depth, nature of bottom
5. Describe the relationship between temperature and dissolved oxygen.
Warmer water holds less dissolved oxygen then cold water, triggering higher plant growth and respiration rates.
6. What is respiration and give the equation. When animals use oxygen to burn up foods
Glucose + oxygen → CO2 + H20 + Heat
6. How does temperature affect respiration? Warmer water, increase plant growth which increase respiration rate.
7. What is thermal pollution and describe 5 sources of thermal pollution? Source of water temperature warming.
Power plants, paper mills discharge water into bodies of water. Rainwater running over warm surfaces, removing of
shade over water, eroding soil causes turbid water, sediment build-up makes stream/rivers shallow heating water up
8. What is turbidity and list biotic causes, abiotic causes? Know sources of turbidity. Amount of cloudiness in a body of
water Low- clear, High- cloudy, Biotic causes: living organic matter, Abiotic- dead organisms, sewage, clay
9. List three chemical properties of freshwater ecosystems. Oxygen, pH, CO2
10. What are the four factors that affect the amount of dissolved oxygen in water? Number of Organisms, Dgree of
activity, water temp, pollutants
11. What is the pH range for well-balanced fish population? Between 6.7 - 8.6
12. What five organisms are index species? Algae, bacteria, zooplankton, fish, bottom fauna
13. Give two examples of keystone species, describe why they are. An organism that is crucial to the way other species
interrelate. The removal would drastically affect the ecosystem.
Sea star- eat mussels if there are too many mussels in crowds out other species.
Ivory tree coral- home for many invertebrate species which provide food for larger fish
14. Briefly describe what happens in an algal bloom.
Sewage, manure, farm run-off Adds nutrients, this causes algae to grow very quickly, forming an algal bloom. Algae are
food for other organisms produce 02, when they die bacteria feed on them and use up oxygen that fish and other
organisms need to survive.
15. Label the light zones in an ocean and be able to describe where the energy comes from for each.
Littoral Zone- shallow zone in a freshwater where light reaches, locate along the shore. Capture solar energy to make
their own food during photosynthesis.
Benthic Zone- is a dark region deep underwater. Located at the bottom. No photosynthesis, food source is dead and
decaying organisms that sink into this zone.
16. Fill in the table below
Water Temperature
Dissolved Oxygen
How does increasing
turbidity affect it?
(Explain your answer!)
Increases temp
Particles absorb heat from
Due to warmer water
Less oxygen
How does thermal
pollution affect it?
(Explain your answer!)
Increase water temp
Hold less oxygen due to
warmer temp
Less oxygen
How does water speed
affect it?
Slow has warmer temp
Slow has less oxygen
Slow has less oxygen
How does water depth
affect it?
Deeper water
Cooler temp
Deeper water
Less plants, less oxygen
Deeper water
Less plants
Less oxygen
Less respiration