Biology Now, 2e

Answers ■ A33

Figure 18.11

Q1: Where will fire most seriously affect the Amazon rainforest?

A1: Fire will most likely affect areas labeled “Dry and/or logged

forest” (shown in orange).

Q2: Where will fire be the least damaging to the Amazon

rainforest?

A2: Fire will least affect the old-growth forest (shown in green).

Q3: This map does not include an increase in pasturelands for

grazing animals. Do you think more or less pastureland will be

needed in 2030? Explain.

A3: As populations increase, the need for more pastureland to

raise cattle for human consumption will increase as well.

Figure 18.12

Q1: What is transpiration?

A1: Transpiration is the process of plants absorbing water through

their roots and releasing this water through their leaves to the

atmosphere.

Q2: Why is transpiration important to the water cycle?

A2: Transpiration returns water from the soil back to the

atmosphere to form clouds and eventually precipitation.

Q3: If there are fewer plants and therefore less transpiration in a

given area, what will happen to the humidity or cloud cover in this

area?

A3: The humidity and cloud cover will decrease where there is a

substantial decrease in transpiration.

Figure 18.13

Q1: How do the patterns of rainfall in the Northern and Southern

Hemispheres compare?

A1: The same patterns emerge as you move away from the equator

either northward or southward.

Q2: How do the patterns in the kinds of environments shown in

the Northern and Southern Hemispheres compare?

A2: As you move away from the equator, the major biomes are

equivalent distances from the equator either north or south.

Q3: What happens at the equator to make this region so wet?

A3: The density of plants is very high, and therefore the amount

of transpiration is very high, resulting in cloud cover and high

precipitation. High precipitation results in high plant growth and

high transpiration rates.

Figure 18.14

Q1: What are three ways that carbon is released into the

atmosphere?

A1: Respiration from animals; the burning of organic matter,

including fossil fuels and wood; and the decomposition of dead

organic material.

Q2: Are all of the pathways you listed for question 1 affected by

human activity?

A2: Almost everything on our planet is affected by human activity

in some way. Of the three pathways of carbon release, the one most

affected by humans is the burning of organic materials for energy.

Q3: What are two biotic reservoirs of carbon?

A3: Plants and animals.

Figure 18.15

Q1: How does a carbon source contribute to global warming?

A1: A carbon source is a reservoir of carbon that releases more

than it absorbs, thereby dumping CO 2 into the environment,

increasing greenhouse gases, and causing global warming.

Q2: How does a carbon sink protect against global warming?

A2: A carbon sink absorbs more carbon than it releases, thereby

removing CO 2 from the environment, decreasing greenhouse

gases, and blocking global warming.

Q3: How can trees act as both a source and a sink?

A3: Trees act as a carbon sink when photosynthesizing and

absorbing CO 2 and as a carbon source when they are burned for

fuel or in a wildfire.

CHAPTER 19

END-OF-CHAPTER ANSWERS

1. d


2. b


3. c


4. d


5. a


6. Density-dependent, density-independent


7. b


8. c


9. (a) 1, (b) 4, (c) 3, (d) 5, (e) 2


10. (See figure below)


11. The food dispenser increased the carrying capacity
    significantly.


12. b

Prey

Predator

Time

Population size

Prey carrying

capacity (K)

Predator carrying

capacity (K)