Biology: Concepts and Investigations

Mariëlle Hoefnagels

Chapter 37 Communities and Ecosystems - all with Video Answers

Educators

Chapter Questions

01:36

Problem 1

How does a community differ from an ecosystem?

Alexander Clippinger

Numerade Educator

01:37

Problem 2

How does a habitat differ from a niche? Describe your own habitat and niche.

Alexander Clippinger

Numerade Educator

01:17

Problem 3

How can two species share the same habitat without one driving the other to extinction?

Alexander Clippinger

Numerade Educator

02:00

Problem 4

Describe and give examples of three types of symbiotic relationships.

Alexander Clippinger

Numerade Educator

02:36

List examples of adaptations that enable an organism to compete with other species, live inside another species, find food, and avoid herbivory or predation. How does each adaptation contribute to the organism's reproductive fitness?

Alexander Clippinger

Numerade Educator

01:43

Problem 6

In one type of mimicry, a harmless species such as a jumping spider physically resembles a noxious species such as an aggressive type of ant. Explain why this type of mimicry can exist only if the spiders are less abundant than the ants.

Alexander Clippinger

Numerade Educator

02:45

Problem 7

What is a keystone species? How do researchers design experiments that help them identify keystope speries?

Alexander Clippinger

Numerade Educator

02:59

Problem 8

How is natural selection apparent in ecological succession?

Alexander Clippinger

Numerade Educator

01:43

Problem 9

Why are true climax communities rare?

Alexander Clippinger

Numerade Educator

04:31

Problem 10

After fires destroyed much of Yellowstone National Park in 1988 forest managers suggested humans could help the areas recover by feeding deer, bringing in plants, and planting trees. What are some advantages and disadvantages of intervening in recovery from a disaster?

Alexander Clippinger

Numerade Educator

01:54

Problem 11

When Mount St. Helens erupted in 1980 , areas nearest the volcano were totally devastated. Farther away from the blast site, however, the disturbance was more mild. Predict how the rate of forest succession would change with distance from the volcano, and explain your prediction.

Alexander Clippinger

Numerade Educator

01:26

Problem 12

Can you think of an example of an organism that is both a producer and a consumer?

Alexander Clippinger

Numerade Educator

01:27

Problem 13

Identify a consumer in an ecosystem not mentioned in the text.

Alexander Clippinger

Numerade Educator

01:40

Problem 14

Krill are tiny, shrimplike plankton that are abundant in Antarctic waters. Some people have suggested that we "farm" the krill in Antarctic waters and use it to feed people who are starving. Predict the effects of krill farming on the Antarctic ecosystem.

Alexander Clippinger

Numerade Educator

02:09

Problem 15

In a long-term study of a tropical rain forest in Puerto Rico, researchers studied the aftermath of hurricanes Hugo and Georges. Tree debris supported the growth of detritivores. Beetles and flies ate the detritivores. Propose a food chain and trace how the booming insect populations might eventually benefit top predators such as birds and snakes in the forest. What do you predict happened to fruit- and nectar-eating animals immediately after the storm?

Alexander Clippinger

Numerade Educator

08:04

Problem 16

As the human population in the United States has increased, we have reduced or eliminated the populations of top predators such as wolves and coyotes. How might this history relate to the recent explosion of deer populations? Using the ecological principles you have learned in this chapter and chapter $36,$ what are some possible ways to reduce deer populations? What are the pros and cons of each approach?

April Townson

Numerade Educator

01:17

Problem 17

Pigs and chickens in commercial farms may eat food made from herrings, anchovies, and other fish. What are some possible consequences to marine food webs?

Alexander Clippinger

Numerade Educator

02:07

Problem 18

In the United States alone, tens of millions of domesticated cats consume hundreds of millions of songbirds. Use the Internet to learn more about songbird diets, then predict how predation by cats might affect the rest of the food web.

Alexander Clippinger

Numerade Educator

03:01

Problem 19

Some farmers and ranchers kill the prairie dogs on their land. Use the Internet to research the ecology of prairie dogs and some of the techniques used to control prairie dog populations. How does each technique affect the prairie ecosystem?

Alexander Clippinger

Numerade Educator

02:52

Problem 20

Use the second law of thermodynamics and a pyramid of energy to explain why most food chains have four or fewer levels.

Alexander Clippinger

Numerade Educator

00:54

Problem 21

Some forms of mercury biomagnify in aquatic food chains. High concentrations of mercury in fish are prompting health advisories that warn pregnant women not to eat tuna and some other fish species. From this information, do you think tuna is an herbivore or a carnivore? Explain your reasoning. What properties do you predict that mercury shares with DDT and other pollutants that biomagnify as they ascend food chains?

Ronald Prasad

Numerade Educator

02:52

Problem 22

How do organisms return water, carbon, nitrogen, and phosphorus to the abiotic environment?

Alexander Clippinger

Numerade Educator

02:06

Problem 23

Use the carbon cycle to trace a hypothetical path of a carbon atom from Abraham Lincoln's body into your own.

Alexander Clippinger

Numerade Educator

01:59

Problem 24

Suppose your friend says "I hate germs! I wish we could kill all the bacteria in the world!" What would happen to your friend if she didn't harbor bacteria in her own body? What would happen to nutrient cycles without bacteria?

Alexander Clippinger

Numerade Educator

01:34

Problem 25

Several sites on the Internet offer water- or carbon-footprint calculators. Choose one and compute your footprints. What are the assumptions that go into these calculations? What strategies could you use to reduce either footprint?

Christie Gilbert

Numerade Educator

02:59

Problem 26

Use the Internet to look up the components of a so-called "lowcarbon" diet. How does each element of a low-carbon diet help reduce $\mathrm{CO}_{2}$ emissions into the atmosphere?

Alexander Clippinger

Numerade Educator

02:31

Problem 27

Review the structures of organic molecules in chapter $2 .$ How do the molecules in living cells create interconnections between the carbon, nitrogen, and phosphorus cycles?

Josee Pacheco

Numerade Educator

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