ECOSYSTEMS

As a result of studying various ecosystems:

Students understand that while matter is recycled in an ecosystem, there is a one-way flow of energy in ecosystems.

• Describe the oxygen, carbon and nitrogen cycles and explain their significance. (LIA1)

A sprig of an Elodea plant was placed in a test tube as shown below. The test tube was then placed in sunlight for 6 hours.

1. The bubbles of gas in the diagram are composed mainly of

a. carbon monoxide
b. carbon dioxide
c. nitrogen
d. oxygen

2. Which of the following properties of the Earth is the result of the processes of living things?

a. The Earth’s oceans are salty.
b. The Earth has magnetic poles.
c. The Earth’s atmosphere contains a lot of oxygen.
d. The Earth’s crust contains a lot of volcanic rock.

• Explain how carbon dioxide and water are converted into energy-rich foods through an energy capturing mechanism (photosynthesis). (LIA2)

The following equation represents the process of photosynthesis in green plants.

(Carbon Dioxide + Water, in the Presence of Light and Chlorophyll!Sugar + Oxygen)

3. What happens to most of the light energy during photosynthesis?

a. It is transformed into heat energy.
b. It is transformed into chemical energy.
c. It is changed into carbon dioxide.
d. It is changed into oxygen.

4. Which statement about green plants is true?

a. Most green plants do not need food.
b. Most green plants take in food through their roots.
c. Most green plants take in food through their leaves.
d. Most green plants manufacture their own food.

• Describe the transfer of energy from the sun to the environment and back to space, through food webs consisting of producers, consumers and decomposers. (LIA3)

A group of organisms that interact with and depend upon one another is called a community. The movement of matter and energy through a community can be studied by examining its food web. As organisms eat other organisms, energy and nutrients pass through various feeding levels. These feeding levels are called trophic levels. The following is a diagram of the energy and nutrient flow through a simple community.

5. Which group would most likely contain living algae?

a. producers
b. first-order consumers
c. second-order consumers
d. decomposers

6. According to the diagram, nutrients from dead organisms are released into the soil by the action of ________.

a. producers
b. first-order consumers
c. third-order consumers
d. decomposers

The diagram shows part of an aquatic food web for a stable lake ecosystem in Connecticut.

Students understand how the number and variety of organisms and populations are dependent on the resources and physical factors of their environment.

• Explain how changes in resources, predation and climate can affect the growth of different populations. (LIB1)

8. The highest concentration of life exists in the top 200 meters of ocean water. The most important factor that influences this concentration of life is the

a. amount of gases at the surface.
b. amount of nutrients in the water.
c. large number of predators at lower depths.
d. amount of sunlight.

In the longstanding war between coyotes and sheep ranchers in New Mexico, studies show that coyotes kill sheep and the percentage of sheep lost from herds in areas where coyotes have been exterminated is about the same as the percentage lost in areas where coyotes are still present.

9. What is the most likely explanation for the similarity in the percentage of sheep lost in both areas?

a. Coyotes were protecting sheep.
b. The sheep died from overcrowding.
c. Another predator was killing sheep.
d. Coyotes were preying on sick or weak sheep.

Effects of Hurricane Hugo on Bat Species

10. Bats comprise 75 percent of the mammals native to Puerto Rico. In 1989, Hurricane Hugo flattened a large section of the rain forest in Puerto Rico. Researchers collected data about the effects of the hurricane on three different species of bats. The results are shown in the chart above.

A. Discuss three possible reasons for the changes in the bat populations.

B. Predict the role the bats would have in the recovery of this rain forest.

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• Explain how organisms are adapted to environmental conditions in different biomes. (LIB2)

11. Study the picture of the imaginary animal below. Based on its features, make scientific inferences about the animal’s habitat and about its niche. In other words, tell about the kind of area it might live in, what it might eat, and what role it might play in its community. Be sure to explain your reasoning.

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12. Sponges are sessile (permanently attached organisms) and rely on water currents for their survival. Which biological process(es) are directly affected by this way of life?

a. reproduction and feeding
b. response and growth
c. development
d. protein synthesis

• Explain how human activity can impact the stability of various ecosystems. (LIB3)

13. For a long-term ecology study, a meadow in a large forest is divided into two plots. One plot is mowed once a year, while the other plot is not. Describe what each plot will look like after 40 years and justify your answer.

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14. A company wants to build a factory to produce weed killer. The new factory will be located close to the lake ecosystem with the food web shown in the diagram above. What would happen if weed killer from the factory were to pollute the lake? In your response, be sure to include two ways the aquatic food chain could be affected.

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