Deck 38: Communities and Ecosystems

Question 1

Nuisance aquatic plants such as Hydrilla can disrupt the ecology of the littoral zone of a lake. Two of the most common ways to control nuisance aquatic plants are herbicides (chemicals that kill plants) and biological control (introducing fungi or animals that consume the plants). How might each strategy help or harm the lake ecosystem?

Answer 1

The herbicides could help by reducing the plant before it chokes out resources; however, it may also kill beneficial plants, disrupting the food sources of other organisms.  Biological controls could also reduce the nuisance plant without introducing toxins.  However, the introduced organisms could begin killing desirable plants, or they may themselves become a nuisance.

Question 2

How do climate and soil composition determine the characteristics of terrestrial biomes?

Answer 2

Climate and soil composition determine which plants and microorganisms can grow in a particular area. The plants, in turn, influence the animals and other organisms that live there.

Question 3

Describe how and why photosynthetic activity differs in the zones of a lake or ocean.

Answer 3

Because light penetrates water to different degrees at different depths, photosynthetic activity is highest near the surface and declines with depth. In both lakes and the ocean, the photic zone is the only area where photosynthesis can occur. Photosynthetic rates are generally highest near the shore, where nutrients are most abundant.

Question 4

List and describe the climate, soils, and inhabitants of each of the major terrestrial biomes.

Question 5

Describe the physical and chemical differences between the water in a mountain stream and the water near the mouth of the Mississippi River.

Question 6

Which biomes are supported by fire and grazing?

Question 7

Make a concept map depicting the relationships among the zones of the ocean. What is the main energy source in each zone?

Question 8

Describe the types of organisms that live in each zone of a lake or pond.

Question 9

What factors determine the location of each biome on Earth?

Question 10

The biomes described in this chapter do not include those that humans create, such as cities, villages, croplands, rangelands, and tree farms. How are these biomes similar to and different from the biomes in this chapter?

Question 11

What is the difference between an oligotrophic and a eutrophic lake?

Question 12

How does the fact that Earth is a sphere tilted on its axis influence the distribution of life?

Question 13

Use the Internet to learn about cave ecosystems. What are some possible energy sources in a cave? How do cave ecosystems interact with other ecosystems? How might the abiotic conditions in a cave select for unique adaptations in cave-dwelling organisms? How do human activities affect caves?

Question 14

How does a river changes from its headwaters to its mouth?

Question 15

What types of forests occur on Earth, and what combination of conditions favors each type?

Question 16

Some scientists are currently attempting to catalog all of the world's biodiversity. What are some of the technical problems they may encounter?

Question 17

Describe some of the adaptations that characterize organisms in estuaries, intertidal zones, and coral reefs.

Question 18

Explain why the climate on the west side of Oregon's Cascade Mountains is much wetter than on the east side of the mountain range.

Question 19

Suppose you are exploring the chaparral ecosystem in California. You encounter a shrub species that you think may be fire-adapted, and you wonder whether the plant can reproduce in the absence of fire. Design an experiment that would help answer your question.

Question 20

List and define the major zones of the ocean.

Question 21

How do tropical savannas differ from temperate grasslands?

Question 22

Researchers and citizens in Prairie City, Iowa, are reconstructing the prairie by collecting seeds from remnants of native grasslands and reintroducing animals. Which other biomes discussed in the chapter might it be possible to reconstruct and which not?

Question 23

How is upwelling important to ocean ecosystems?

Question 24

List adaptations that characterize organisms in each of the following biomes: tropical rain forest, savanna, temperate grassland, tundra, desert, taiga, the rocky intertidal zone, the bottom of a lake.

Question 25

Hundreds of millions of years ago, Earth's land masses were joined into one supercontinent, Pangaea. If Pangaea had never broken up, do you think there would be more biodiversity, less biodiversity, or the same amount of diversity as today? Explain your answer.

Question 26

Explain how researchers tested the adaptive bleaching hypothesis.

Question 27

List examples of coastal ecosystems.

Question 28

What are the relationships among ecosystems, communities, biomes, and the biosphere?

Question 29

What are the benefits and limitations of field studies and lab experiments in testing the adaptive bleaching hypothesis?

Question 30

How can the tropical rain forest support diverse and abundant life with such poor soil?

Question 31

What abiotic conditions influence the distribution of species in the biosphere?

Question 32

What is permafrost, where does it occur, and how does it affect primary production in that biome?

Question 33

How do the main factors affecting primary production differ between land and water?

Question 34

Polar bears live on the ice cap near the North Pole. Their numbers are dwindling, apparently because of both pollution and global climate change. Ice on Canada's Hudson Bay, for example, is melting about 3 weeks earlier in the year than it was some 30 years ago. List some specific ways that this change in habitat might affect polar bear populations.

Question 35

Explain why sunlight is most intense at the equator.

Question 36

A watershed is an area of land in which all of the precipitation drains into the same body of water. The central United States, for example, is in the Mississippi River's watershed, which itself consists of many smaller watersheds. Why would cities and towns that share a watershed want to cooperate to manage water resources? Why might one part of a watershed face different issues from another part?

Question 37

Moving outward from the equator, what are the major climatic regions of the world?

Question 38

Poultry farmers apply large amounts of nutrient-rich animal waste onto the land, where it runs off into nearby lakes and streams. What effect might this nutrient input have on the aquatic ecosystems? Lawmakers in some states have debated whether animal waste, a natural substance, should legally qualify as a hazardous waste. Do you think it should?

Question 39

How do prevailing winds, ocean currents, and mountain ranges affect climate?