Base your answers to questions 1 through 3 on the food web represented below and on yourknowledge of biology. The food web contains some of the organisms found in Glacier National Park.

1. Describe how the niche of the mouse population differs from the niche of the shrew population in thisecosystem. Support your answer with information from the food web.

2. Explain why a major increase in the number of cloudy days that extends over a period of years wouldbe expected to affect the populations of both plants and animals in this ecosystem.

3. Identify which group of organisms in this food web would contain the greatest amount of storedenergy. Support your answer.

Base your answers to questions 4 through 6 on the passage below and on your knowledge ofbiology.

The lake sturgeon is a fish that often grows over six feet long and can weigh close to twohundred pounds. It is currently an endangered species in the Great Lakes area, although thespecies has lived in those lakes and rivers for millions of years. Now, there is a program toincrease the sturgeon population by reintroducing lake sturgeon to areas where they havedisappeared. Like the lake sturgeon, bloater fish are also found in the Great Lakes. Both find their food on ornear the bottoms of lakes. They eat a variety of small organisms, including insect larvae, worms,and clams. These small organisms feed on algae.

4. Identify which population, other than lake sturgeon, will increase in size after the lake sturgeon areadded to the new ecosystems. Support your answer.

5. State what the arrows in the food web represent.

6. Identify one population that will decrease in size after the lake sturgeon are added to the newecosystems. Support your answer.

7. Stable predator-prey relationships are necessary to maintain a healthy ecosystem. The removal of apredator species from an area caused the deer population to sharply increase from 1910 to 1925.Changes in the deer population and carrying capacity of the area are represented in the graph below.

Based on the information provided, explain how the sharp population increase from 1910 to 1925might have resulted in the decrease in the carrying capacity after 1925.

8. Base your answer on the information below and on your knowledge of biology.

A student measured oxygen and carbon dioxide concentration levels in an aquatic ecosystemduring a 24 hour period. The data are represented in the graph below.

Identify two biological processes that are responsible for the production of varying amounts of carbondioxide and oxygen within the aquatic ecosystem.

9. Base your answer to the following question on the information below and on your knowledge ofbiology.

If farm fields in the Piedmont region of North Carolina are abandoned, there is a regularsequence of plant species that will inhabit the field. The data table below shows a typical sequenceof dominant plant species.

A) degrading of the ecosystem B) loss of biodiversityC) ecological succession D) biological evolution

This regular sequence of plant species over the 150-year period is known as

A) A B) B C) C D) D

10.Events that occur in four different ecosystems areshown in the chart below.

Which ecosystem would most likely require the mosttime for ecological succession to restore it to itsoriginal state?

11. Base your answer to the following question on the diagram below, which represents the changes in anecosystem over a period of 100 years, and on your knowledge of biology.

State one biological explanation for the changes in types of vegetation observed from A through C.

Base your answers to questions 12 through 14 on the information below and on your knowledge ofbiology.

Coral Reef Ecosystems

There are many ecological interactions that maintain the biodiversity present in coral reefs. Inaddition to coral, microscopic algae, seaweed, sea grasses, sponges and worms, and a variety offish are among the organisms that live in reef ecosystems. Ocean currents often link different reefsystems and move organisms from one reef area to another. This movement is a factor inrepopulating a reef that has been damaged by environmental changes. One environmental change involves an increased growth of seaweed. When the population ofseaweed increases, the reef shifts from a coral-dominated ecosystem to a seaweed-dominatedecosystem. This change disrupts the relationships between the organisms that live there. Studies have shown that, as the density of seaweed in a reef area increases, the number of fishthat eat the seaweed in that area decreases. This may be due to the presence of more predators, orthe taste of the more mature plants. The fish move to areas where there is less seaweed growth. Asthis trend continues, the reef areas are taken over by the seaweed. Once this happens, it is veryhard to remove the seaweed and restore the reef to a healthy ecosystem. In addition to this problem, temperature changes are threatening the ocean currents thatconnect the reef systems. A change in the currents would reduce the movement of fish larvae fromone area to another. This contributes to the seaweed problem.

12.Identify one abiotic factor that is affecting the stability of the coral reef ecosystems and state how thefactor identified is important to the coral reef ecosystems.

Abiotic factor:

Effect:

13. State one reason why it is important to maintain the stability of the coral reefs.

14. State the role of the sea grasses in the reef ecosystem.

15. Base your answer to the following question on the information and graph below and on yourknowledge of biology. The graph contains information about an ecosystem.

The graph below shows the carrying capacities of an ecosystem for three different species, 1,2, and 3, that inhabit an area and the actual population sizes of these three different species in thearea.

Identify which species population would most likely have the greatest competition among itsmembers. Support your answer using information from the graph.

Species number: __________

Base your answers to questions 16 and 17 on the information below and on your knowledge ofbiology.

Project Frozen Dumbo - Saving the Elephant Population Means Using Special Breeding

Over the last 10 years, 70 percent of Africa's wild elephant population has been killed off. Themain cause is ivory poaching, in which elephants are slaughtered for their valuable tusks. At thesame time, efforts to breed captive zoo elephants have not been very successful. Now there is some good news. At zoos in Austria and England, two baby elephants were born,using sperm from South African wild elephants. For the first time, elephant sperm gathered in thewild was frozen and given to zoos. Two female zoo elephants were artificially impregnated withthe sperm and went on to deliver calves....Source: Saving the Elephant Population Means Using Special Breeding, Pittsburgh Post-Gazette,8/21/14

16. Identify one likely reason, other than poaching and hunting, for the decline of the elephantpopulation.

17. State one reason why the use of sperm from wild elephants, rather than the use of sperm fromelephants in zoos in England or Austria, would be more important to the long-term survival ofelephants.

18. Base your answer to the following question on the diagram below and on your knowledge of biology.The diagram indicates a change in an ecosystem.

Identify one natural event that could cause the disruption indicated in the diagram.

Base your answers to questions 19 and 20 on the information and passage below and on yourknowledge of biology.

Snowy Owls Move to the South Snowy owls are large white birds that normally inhabit the cold northern regions of Canada.Recently, scientists and birdwatchers have sighted the snowy owls much farther south than usual. When snowy owls are in northern areas, they feed on lemmings (small rodents). Whenlemmings are not available, as in the areas further south, the owls will seek out mice or rabbits astheir food source. Several snowy owls migrated into an area represented by the food web below.

19. State which level, A, B, or C, contains the least total available energy. Support your answer.

Level:

20. Identify one population of organisms shown in the food web, other than rabbits or mice, that wouldlikely be affected by the introduction of the snowy owls and explain why their population would beaffected.

Population affected:

Answer KeyEcology

1. — Shrews are predators of spiders, while miceeat plants.— Mice are herbivores/primary consumers andshrews are carnivores/tertiary consumers.— Mice are food for both weasels and foxes,while shrews are only eaten by weasels.— Mice compete with spruce grouses for food,while shrews compete with weasels for spiders.

2. — Both the plants and animals would benegatively affected, since the rate ofphotosynthesiswould slow down with less light from the Sunavailable, and less food would be available foranimals to eat.— The plant and animal populations wouldboth decrease with less energy available forthembecause of less light for the plants.— These organisms would have less foodbecause of less photosynthesis occurring, sotherewould be fewer of them.— It would affect both plants and animalsnegatively, because the plants would receivelesslight to make food.

3. — The greatest amount of stored energy in thisfood web would be in the plants because theyobtain energy directly from the Sun.— Plants would, since they are theproducers/autotrophs.— Plants, seeds, needles, and leaf litter wouldhave the most energy because they are at thebase of the energy pyramid/beginning of foodchains.

4. — Algae, because there will be fewerorganisms that feed on them. — More algaewill survive and reproduce because populationsof insect larvae, clams, and worms that eat thealgae will decrease in size because they will beeaten by both lake sturgeon and bloater fish.

5. — The arrows show the direction of energymovement from one organism to another.—The arrows show the flow of energy. —movement of nutrients through the food web,— what each organism feeds on

6. — Populations of insect larvae [or clams orworms] will decrease in size because they willbe eaten by both lake sturgeon and bloater fish.—The bloater fish population will decrease insize because it will have to compete with thelake sturgeon for food resources. — clamsbecause they are eaten by the sturgeon

7. — The overpopulation of deer in 1925 causedtheir habitat to be overgrazed. This did notallow the food sources in the area to regrow forfuture deer populations. — In 1925, the deerate too much food, lowering the amount offood available in future years. —Overpopulation of deer in 1925 destroyedsome of the resources deer needed, so fewerdeer could live there.

8. — respiration and photosynthesis —photosynthesis and aerobic respiration —photolysis and respiration

9. C10. C11. Examples: — As more soil accumulated (from

the decomposition of dead vegetation), plantswith deeper root systems could live there andshade out the earlier plants — Ecologicalsuccession

12. — temperature: causes a change in currents —light: used by plants for photosynthesis —ocean currents: carry organisms from one reefto another —carbon dioxide: used by plants forphotosynthesis

13. —in order to maintain the food webs that existthere, —because many organisms depend onthem for food or shelter, — to maintainbiodiversity, — keep oceans healthy, — toprevent extinction of reef species

14. —Their role is to convert inorganic (raw)materials into organic matter/food. — Theycapture radiant energy. — They serve as theproducer in this food web/ecosystem. —Theyserve as food for fish. — produce oxygen

Answer KeyEcology

15. – The population size is greater than the size ofthe population that the ecosystem can support.– Because it is above its carrying capacity, theecosystem cannot supply enough food forsurvival, so members of the species competefor limited food.

16. — habitat destruction/loss of food — lack ofreproductive success — illness/disease —Breeding programs were not successful. —climate change — natural predators — lack ofgenetic diversity

17. — It increases genetic diversity/biodiversity.— It increases species variation. — makes theelephant population more diverse — Captiveelephants produce lower-quality sperm.

18. — fire — volcanic eruption — hurricane/flood— earthquake

19. — At each level, as you go up from the plantsto the herbivores to the carnivores, energy islost. — Energy enters the ecosystem withgreen plants capturing energy from sunlight.There is less energy available as it is passed onto the consumers. — Energy is lost at eachfeeding level.

20. — snakes – The owl would compete with thesnakes for the mouse population. — hawks –The owls feed on much of the same food as thehawks, so there would be fewer hawks.— mountain lions – The owls would competefor the rabbit population. — grasses – The owlswould eat rabbits and mice, and there would bemore grass.