ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
08-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological
components of an ecosystem affect populations.
• I’m learning to construct an oral and written argument to explain how disruptions to any physical or biological
component of an ecosystem can lead to shifts in all its populations.
• I’m learning to recognize patterns in data and make inferences about changes in populations.
• I’m learning to describe how changes in one part of an ecosystem cause large changes in another part.
In 1906, northern Arizona’s Kaibab Plateau was declared a park. Mule deer hunting ended, and an effort
was made to eliminate all the predators on the Plateau with the belief that these actions would “protect”
the deer herd. During the next 25 years, the following predators were killed:
 4,889 Coyotes
 781 Mountain lions
 544 Bobcats
 30 Wolves
 ?? An unknown number of golden eagles
The deer population of the plateau is in the chart below.
Year
# of deer
1905
4000
1910
10000
1915
25000
1920
60000
1923
100000
1925
90000
1930
30000
1935
15000
1940
10000
1. Graph the data above to shown the deer population over time in the Arizona Kaibab Plateau.
# of deer
Deer Population Over Time
120000
100000
80000
60000
40000
20000
0
Year
2. What are possible reasons that the deer population in Arizona would explode and then crash?
The deer population of the Kaibab Plateau exploded when predation (hunting) was eliminated and then later
crashed due to starvation.
3. An area of land has enough food, water, shelter and space for only a certain number of animals of a particular
kind. This number is called the area’s carrying capacity. In 1905, the Kaibab Plateau had a deer carrying capacity of
30,000 animals. By 1935, this carrying capacity was reduced to only 10,000 animals. What are some possible
reasons the Plateau’s carrying capacity would change in this way?
Due to serious deer over-grazing plants were damaged long-term meaning less food was available for the deer,
causing the carrying capacity to decrease.
4. Predators are essential to maintaining a balance of population in an ecosystem. Many scientists believe that
death by predators is more natural or right than death by starvation. How do predators help maintain this balance?
ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
Predators reduce the population of species to prevent them from over-populating, resulting in maintaining the
areas carrying capacity.
Questions 5 & 6 refer to the following data collected from a lake.
Organism
Bald Eagle
Striper Bass
Shad
Phytoplankton
5.




Trophic Level
Tertiary Consumer
Secondary Consumer
Primary Consumer
Primary Producer
Description
Large Carnivorous Bird
Carnivorous Fish
Herbivorous Fish
Producer
Biomass (g/m2)
1.5
13.0
40.0
750.0
If the shad population began to die, what would happen to the striper bass?
If shad are removed from the food chain, then the amount of phytoplankton will increase.
If striper bass are killed by disease, then the bald eagle population will decrease.
If the bald eagle population relocates to another area, then striper bass will increase.
If phytoplankton is killed due to toxic runoff, then all organisms will reduce in number.
Least likely to occur: If shad begin to die, then striper bass will begin eating phytoplankton.
6. What is the 10% rule? Be able to apply it to the information in chart above.
Only 10% of the energy is transferred between trophic levels.
If the phytoplankton gets 100,000 calories of energy from the sun, then how much energy will remain in the Bald
Eagle. (100)
Question 7 refers to the data collected between 1985 and 2014.
Year
1985
1995
2000
2005
2014
Average Number of Deer
Per 1,000 Acres
5.7
35.7
142.9
85.7
25.7
7. What is the most likely reason that the deer population decreased for a 30-year period?
There was an increase competition for food which resulted in a drop in the population.
Use the biomass pyramids below to answer question 8.
ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
8. The pyramids above show the biomass of two different ecosystems, which ecosystem is more stable and why?
The ecosystem is more balanced in Pyramid A, because there is more biomass of producers than consumers.
Questions 9 and 10 refer to the following graphs.
9. Which graph represents a population whose growth is being maintained at the carrying capacity of the
environment?
Graph III shows a slight increase initially but then a steady period which means carrying capacity is reached in that
environment.
10. Which graph shows a population with unlimited environmental resources and a birth rate much higher than a
death rate?
Graph II shows a dramatic shift in the population occurring very rapidly this would occur if there was unlimited
food and reproduction rates.
08-LS2-5. Evaluate competing design solutions for maintaining biodiversity and ecosystem services.
• I’m learning to describe changes that are occurring within a population based on data interpretation.
• I’m learning to identify factors that may cause a population to change in size.
• I’m learning to determine the carrying capacity of an area based on data analysis.
• I’m learning to debate the best solution for maintaining biodiversity in specific area.
• I’m learning to create an informational article about the importance of maintaining biodiversity in a specific area.
11. What effects could fracking have on the biodiversity of Madison County?



Fracking could possibly cause the water at Owsley Fork Reservoir to become more acidic.
Fracking could result in chemicals being put into the air.
Fracking would result in soil erosion which would cause the land of Madison County to become arable.
Fracking would NOT make Madison County more aesthetically pleasing which would make the area a more
desirable place to live.
ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
Questions 12 and 13 refer to the food web below.
12. What would result if the spiders were removed from the food web shown?
The number of herbivorous insects would increase and the number of plants would decrease. Spiders prey on
herbivorous insects, so population of herbivorous insects would increase and the population of plants would
decrease.
13. In the above food web, what would happen if the toads suddenly disappeared?
The predaceous insect population would slightly increase. If the toads disappeared from the food web then the
snakes would have still have food to eat. The predaceous insects would have no predator and their population
would increase, causes the herbivorous insect population to drop.
14. As the population of small fish in a lake decreases, the population of large fish that depend on the small fish for
food will
The large fish will decrease in number because their food supply decreased.
Questions 15 and 16 refer to the graphs below.
ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
Rabbit Population 1985-1993
1800
1600
1400
1200
1000
800
600
400
200
0
Plant Population 1985-1993
45000
40000
35000
30000
25000
20000
15000
10000
5000
0
1985 1986 1987 1988 1989 1990 1991 1992 1993
15. What happened to the plant population in 1990 and why?
The plant population is slightly decreasing because of the increasing rabbit population. An increase in the rabbit
population means more plants are being consumed.
16. An herbivore is an animal that only eats plants. What will happen to the plant population as the herbivorous
population increases?
The plant population will decrease because there are more herbivores consuming the plants.
Use the passage below to answer question 17.
Humans benefit from biodiversity every time they eat. Most of the crops produced around the world
originated from a few areas of high biodiversity. Most new crop varieties are hybrids, crops developed by
combining genetic material from other populations. History has shown that depending on too few plants
for food is risky. For example, famines have resulted when an important crop was wiped out by disease.
But some crops have been saved from diseases by being crossbred with plant relatives. In the future, new
crop varieties may come from species not yet discovered.
17. Maintaining biodiversity is critical to world food supply. What are possible consequence if corn was wiped out
by disease?



There would be a shortage of food for livestock.
There would a shortage of crops to harvest for farmers.
There would be no corn ethanol (E-85 Flex Fuel).
Read the following sentences and answer the question below: “When the biodiversity of a region declines, many of
the organisms critical to this filtering process can disappear. So, pressures on the freshwater supply can cause
biodiversity to decrease, which can cut the drinkable water supply even further.”
18. Based on this information, how do water supply and biodiversity effect each other?
Water supply and biodiversity and interconnected and affect each other.
Read the following sentences and answer the question below: “Say a particular species of freshwater frog dies
because its habitat has been depleted in a drought. This means the population of birds that feeds on this frog may
ECOSYSTEMS UNIT ASSESSMENT-STUDY GUIDE
decline as well, as it lacks sufficient food. Conversely, the insects that the frogs fed on may increase in number, as
the frogs are no longer around to keep their population in check.”
19. How might this affect the producers in this ecosystem?
If the frogs are eliminated and the insects the frogs fed on increase in population, the producers would not be able
to supply enough food for the growing population of insects.
20. How can humans help maintain biodiversity? How could they prevent it?


Maintain: protecting habitats, conserving the limited supply of fresh water, and minimizing water pollution.
Prevent: maximizing the amount of fracking in order to obtain more minerals.