Download Ecology Test Review

Ecology Test Review Answer Key
Section 3.1 and 3.2: Energy Flow
1. List and define the six levels of ecological organization.
Individual- a single organism within a species (like you!)
Population- a group of individuals of the same species living in the same area
Community- many populations living together in one area
Ecosystem- a community, plus the abiotic factors in their environment
Biome- a group of ecosystems with a similar climate and biotic members
Biosphere- the entire earth, where all biomes are located
2. What is the main source of energy for ecosystems? The sun!
3. What is the equation for photosynthesis?
CO2 + H2O + sunlight
C6H12O6 + O2
Carbon dioxide + water+ sunlight
sugar + oxygen
4. Define the following terms and give a living example of each:









Producer: an organism that produces chemical energy by doing photosynthesis (plants)
Autotroph: an organisms that makes it own food via sunlight or chemicals in its environment (plants)
Consumer: an organism that gets its energy from eating producers or other consumers (deer, human)
Heterotroph: an organism that gets its food/energy from another organism (deer, human)
Herbivore: an organism that eats producers only (cow)
Carnivore: an organism that eats only other consumers (tiger, owl)
Omnivore: an organisms that eats both consumers and producers (humans)
Detritovore: an organism that feeds off dead material (termite)
Decomposer: an organism that gets energy by releasing enzymes and absorbing nutrients from dead
organisms (bacteria, fungi)
5. Draw a food web using the following information:
 Krill, cod, and whales eat plankton
 Whales and cod eat krill
 Whales eat cod
On your food web, label the following:
 producer; first, second, and third level consumers (in red)
 first, second, third, and fourth trophic levels (in purple)
 show how whales can occupy the second, third, and fourth trophic levels
Krill
Cod
1st, 2
1st, 2nd, 2,
3
Plankton
1st, 2nd,
3rd, 2, 3, 4
Whale
P, 1
6. Draw an energy pyramid using the plankton, krill, cod, and whales above.
Whal
e
Cod
Krill
Plankton
a. How much energy gets passed from one trophic level to the next? 10%
b. What is the main reason why 100% of the energy does not get passed on?
The other 90% of energy that a population can produce is given off as heat as a byproduct of cellular
respiration.
7. Draw a biomass pyramid using the plankton, krill, cod, and whales above.
a. biomass: the mass of all living things at the given trophic level
Whal
e
Cod
Krill
Plankton
It’s the same!
Section 3.3: Cycles of Matter
8. Why is water important to living things?
Water transports key molecules like proteins and sugars, and maintains an internal balance in cells.
9. Define the following terms:
Precipitation: Clouds dropping liquid water back to earth
Condensation: Water vapor cooling to form clouds
Run-off: Precipitation traveling back to bodies of water via running over land
Root Uptake: Plants absorbing ground water and nutrients through soil
Evaporation: Liquid water from oceans, lakes, and streams turning to water vapor and rising into
the atmosphere
Transpiration: Evaporation from plants
10. Why is carbon important to living things?
Carbon is the basis of all organic molecules, like DNA, proteins, carbohydrates, and fats
11. List three ways that carbon dioxide gets into the air.
Respiration by organisms, burning of fossil fuels, volcanic eruptions
12. How is gaseous carbon (CO2) converted to solid carbon that can be used by producers and
consumers?
Plants turn carbon dioxide (CO2) into sugar (C6H12O6) through photosynthesis. Plants are the
producers, so they use their own sugar for energy. Consumers get this sugar by eating plants.
13. How is solid carbon deposited back into the ground?
When organisms die, their carbon returns to the soil by the work of detritivores and decomposers.
14. Why is nitrogen important to living things?
Nitrogen is a major component of amino acids and proteins
15. Define nitrogen fixation and denitrification.
Nitrogen fixation is the conversion of nitrogen gas into solid nitrogen compounds. Trees cannot
absorb nitrogen gas, so bacteria in the soil convert it to usable forms that are passed on to producers
and consumers through root uptake.
Denitrification is the conversion of solid nitrogen compounds into nitrogen gas by bacteria.
16. Why is phosphorus important to living things?
Phosphate makes up the backbone of the DNA molecule in all organisms.
17. What is the main source of phosphorus for plants and animals?
The weathering/erosion of rocks. NOT IN THE ATMOSPHERE!!!
18. How do energy and matter flow differently through ecosystems? Provide an example of each.
Energy moves in one direction, from the sun to producer, to consumer and into the atmosphere.
Matter, like carbon, nitrogen, and water, is recycled between solid, gas, and liquid forms.
Ex: In a forest, douglas fir trees convert light energy into chemical energy via photosynthesis. This
chemical energy, in the form of sugar, is passed on to consumers who use it and convert it to heat
energy. This heat energy is lost into the atmosphere, and not recycled.
Ex: In the carbon cycle, gaseous carbon (CO2) is converted to solid carbon (C6H12O6) through
photosynthesis. Organisms then convert this solid carbon back to gaseous carbon through cellular
respiration. Carbon cycles back and forth through this process.
Section 4.1: The Role of Climate
19. What is the difference between climate and weather?
Weather is the daily condition of an area (rainy, cloudy, etc.), while climate is the average, year-afteryear, temperature and precipitation of an area.
20. What are the four major contributors to climate?
The four major contributors to climate are temperature, sunlight, ocean currents, and wind currents.
Unequal heating of the earth’s surface by the sun, based on latitude, causes climate differences.
21. Define ‘range of tolerance’ and explain why salmon are dying in dammed rivers.
A range of tolerance is the range of abiotic conditions where a species can live. Salmon are dying
because dams on rivers are causing an aquatic environment that is outside their range of tolerance.
Salmon prefer to lay their eggs in cool, fast-running, rocky rivers, and dams make rivers warm,
stagnant, and deep. No salmon babies = dying salmon populations.
22. What are the earth’s three climate zones?
Tropical, temperate, polar
23. What is the greenhouse effect?
The greenhouse effect is the trapping of heat energy from the sun by greenhouse gases. Light energy
from the sun enters the atmosphere and is converted to heat energy when it bounces off of earth.
Gases capture some of this energy, keeping our planet at a habitable temperature. These gases are
carbon dioxide, methane (CH4), and water vapor.
24. What is the greatest contributor to excess CO2 in our atmosphere?
The burning of fossil fuels like coal, natural gas, and oil
25. What are three consequences of global warming?
a. the rise of sea levels from 7-23 inches worldwide
b. stronger storms and droughts as we disrupt global wind and ocean currents
c. extinction of organisms forced outside of their range of tolerance
d. lack of fresh water for communities relying on ice and snow packs
Section 4.2: Interactions in Ecosystems
26. What is a niche?
A niche is the role that an organism plays in an ecosystem. Part of this role is the food and shelter
sources an organism uses. For example, to be a decomposer or a producer is a niche.
27. What is the competitive exclusion principle?
The competitive exclusion principle explains that no two species can occupy exactly the same niche.
One will outcompete the other, and the other will either evolve or go extinct.
28. Define and give an example of the following:
Predation: a relationship in which an organism eats another to obtain energy. Example: humans
eating chickens.
Parasitism: a relationship in which one species benefits, and the other suffers. Example: leeches
attach themselves to fish, sucking their blood.
Commensalism: a relationship in which one species benefits, and other sees no
advantage/disadvantage. Example: microscopic ticks feed off of your dead skin cells; you don’t
even know they’re there!
Mutualism: a relationship in which both species benefit. Example: clown fish live in sea anemone
tentacles, gaining protection from predators. The sea anemone gets cleaned of parasites by the
clown fish.
29. What is an invasive species, and how do they cause the extinction of native species?
An invasive species is an organism that is not native to an ecosystem- it has immigrated from
elsewhere. These species are a problem because they compete for resources with native species and
cause their extinction.
Section 5.1: Populations Basics
30. What are population size and population density?
Population size: the number of organisms in a population (all of the same species)
Population density: the number of organisms per area of land
31. Write an equation representing the growth rate of a population.
(births + immigration) – (deaths + emigration) = growth rate
32. Draw a graph representing exponential population growth. Label the axes.
33. Why is exponential population growth hard to find in nature?
Populations always encounter limiting factors, like space and food, that stop their growth.
5.2: Limits to Population Growth
34. List two biotic and two abiotic factors that limit population growth.
Biotic: predators, disease, competition
Abiotic: natural disasters, habitat destruction, weather
35. Of the above factors you listed, which depend on population density (density-dependent) and which limit
population regardless of density (density-independent)?
Biotic factors depend on density, while abiotic factors are density-independent
36. Populations have a carrying capacity. Define carrying capacity and give an example.
Carrying capacity is the maximum amount of organisms an environment can support over time.
For example, northwest forests can only support a few cougars because of a finite amount of food and
territory.
37. Answer the following questions for the graph below:
O
X
a. Draw a logistic graph
b. Put an ‘x’ where the population is increasing exponentially. Put a ‘o’ where the birth and death rate
are equal.
c. Why is this graph a more accurate representation of population growth than an exponential curve is?
It takes into account limiting factors, like food, disease, and space
Human Impacts on the Environment
38. Define and give an example of:
a. Renewable Resources
Renewable resources will regenerate themselves if used wisely. Ex: fish, trees
b. Non-Renewable Resources
Non-renewable resources will not regenerate themselves; when gone, they’re gone! Ex: fossil fuels
39. List three ways that humans are depleting renewable resources.
Overfishing: taking so many fish that not enough are left to reproduce and replenish stock
Deforestation: cutting trees down without replacing them, or replacing them without time to grow to
usable size
Overharvesting: mass planting/harvesting without allowing plants to die and return nutrients to soil
40. What does the movement for sustainable development advocate?
Using the earth’s renewable resources wisely, allowing them to regenerate for use of future
generations