Environmental Science
Study guide for Chapter 5 Test
1. Define photosynthesis.
Process by which plants, algae, and some bacteria use sunlight carbon dioxide (CO2) and water (H2O) to
produce carbohydrates and oxygen (O2).
2. List two names for organisms found on the bottom level of a food web/pyramid.
Producers; Autotrophs (self-feeders)
3. Describe another way bacteria could make food without sunlight.
Chemosynthesis (use chemicals to make food)
4. Define consumer. Give an example of a primary, secondary and tertiary consumer.
Organisms that get their food by eating other organisms. Consumer also called Heterotroph (eats
others)
Primary: (eats plants; called herbivore): cow, deer, insect
Secondary: (eats Primary): wolf, human (human eats cow), bird
Tertiary: (eats Secondary): eagle (eats bird)
5. Describe what the four types of consumers eat.
Herbivores: eat plants
Carnivores: eat meat (other animals)
Omnivores: eat plants and meat
Decomposers (also called Detrivores): eat dead stuff (breaks it down to release nutrients): fungi
6. What is the purpose of cellular respiration?
Produce energy from the breakdown of carbohydrates
7. How is excess energy stored in the body?
As fat or sugar
8. Each time an organism eats another organism, an _______________ transfer occurs.
Energy
9. Each level of a food chain/web is called a _________________ level.
Trophic
10. Describe the difference between a food chain and food web.
Food Chain: sequence in which energy is transferred from one organism to the next as each organism
eats another organism. (In the form of a single chain, or line)
Food Web: many feeding relationship that are possible in an ecosystem (many food chains intertwined).
11. Which (web or chain) is a better representation of how an environment works? Why?
Web; ecosystems contain more than one chain
12. Each time energy is transferred, some of the energy is lost as ____________.
Heat
13. Why do there have to be more organisms at the bottom of the energy pyramid than at the top?
Because there is less energy available at higher trophic levels (energy is lost as heat as move up the
pyramid).
14. Describe what happens in the carbon cycle.
Movement of carbon from nonliving environment into living things and back.
Air to Producers to Consumers to Decomposers to ground/water/air.
15. How does carbon exist in the atmosphere?
As carbon dioxide (CO2)
16. Is carbon important to living things? How?
Yes: essential component of proteins, fats, and carbohydrates.
17. How do plants remove carbon from the atmosphere?
Convert carbon dioxide (CO2) into carbohydrates during photosynthesis,
18. How does carbon relate to our energy sources? (How do we use carbon as fuel)
Bodies of organisms long dead in soil become coal, oil or natural gas (fossil fuels)
19. How do consumers obtain carbon?
Eat Producers
20. What substance stores carbon? (carbon sink)
Limestone
21. How does carbon return to the Earth once the organism has died?
Decomposers break down organisms to release nutrients
22. Flashback: Are fossil fuels renewable or nonrenewable resources?
NONRENEWABLE
23. How do humans affect the Carbon Cycle?
Burn fossil fuels to release carbon into atmosphere; returns as carbon dioxide; increased levels
contribute to Global Warming. which is an increase in the Earth’s temperature.
24. Describe the effect of global warming.
An increase in the Earth’s temperature.
25. Describe the nitrogen cycle.
Process in which nitrogen circulates among air, soil, water, plants, and animals in an ecosystem.
Nitrogen in air to plants as ammonia (done by nitrogen-fixing bacteria on plant roots) to animals to
decomposers to soil/water/air.
26. Nitrogen makes up ___________of the gases in the atmosphere.
78%
27. What type of organism is capable of converting atmospheric nitrogen into ammonia?
Nitrogen-fixing bacteria on roots of plants
28. What type of plants coexists with this tiny organism?
Legumes (ex: beans, peas, clover)
29. What element of weather also converts nitrogen?
Lightning
30. Describe the phosphorus cycle.
Cyclic movement of phosphorus in different chemical forms from environment to organisms and back to
environment. PHOSPHORUS NEVER GOES INTO THE AIR.
Soil/water to Producers to Composers to Decomposers to environment
31. Where do plants obtain phosphorus?
Into their roots from the soil.
32. Where do animals obtain phosphorus?
Eating plants (or other animals that ate plants)
33. How does erosion affect the phosphorus cycle?
Rocks erode and small amounts of phosphorus dissolve as phosphate which moves into soil.
34. Which two element cycles can be found in fertilizers?
Nitrogen and phosphorus
35. What happens to these elements once it rains?
Excessive amounts end up in aquatic (water) ecosystems as runoff; causes rapid growth of algae which
can deplete oxygen and cause fish kills.
36. What is acid precipitation?
Produced by nitric acid in rain or snow
37. Describe ecological succession in general.
Gradual process of change and replacement of type of species in a community
38. Contrast a pioneer species and climax community. (How are they different)
Pioneer Species: Colonizes uninhabitable area and starts ecological cycle in new area that will become
habitable for other species.
Climax Communities: Final stable community in equilibrium with environment.
39. Describe primary succession. Give an example of some causes of primary succession.
Succession that occurs on a surface where no ecosystem existed before.
Causes: New island created by volcano
40. Describe secondary succession. Give an example of some causes of secondary succession.
Occurs on a surface where an ecosystem previously existed; process by which one community replaces
another community that has been partially or totally destroyed.
Cause: disruptions by humans or animals; storms; floods; earthquakes; volcanic eruptions; lightning
strikes/fires.
41. How are natural fires caused by lightning are a necessary part of secondary succession?
Remove accumulations of brush and deadwood that could lead to major fires’ some animals feed on
vegetation that sprouts after a fire has cleared the land; some plants/trees seeds will not sprout until
after a fire.
42. Define old field succession.
Type of secondary succession that occurs when farmland is abandoned.