A32fiffAnswers
A2: The Neanderthal has a more pronounced eyebrow ridge and
more sloping forehead.
Q3: Why would you expect a hybrid of Neanderthals and modern
humans to have intermediate features?
A3: In hybrids, half of the DNA would be from Homo sapiens
and half from Homo neanderthalensis. Hybrids have features
of both parents. Some might have intermediate features, while
others could have mixed features (such as a sloping forehead but a
prominent chin).
CHAPTER 18
END-OF-CHAPTER ANSWERS
- e
- b
- d
- (a) 1, (b) 3, (c) 4, (d) 2, (e) 5
- Weather, climate, Climate change, global warming
- d
- Carbon sink, because more carbon is absorbed in the years
between the fires than is produced by the fires.- (a) 4, (b) 1, (c) 2, (d) 5, (e) 3
- c
- Answers will depend on student location.
- Answers will depend on student location.
ANSWERS TO FIGURE QUESTIONS
Figure 18.3
Q1: List as many biotic and abiotic factors in this photograph as
you can.
A1: Biotic: all living things, such as plants, as well as all animals,
including microscopic bacteria and algae. Abiotic: all nonliving
things, such as rocks and water.
Q2: Is the forest part of the biotic or abiotic environment? Explain.
A2: It can be considered both. The plants and microorganisms are
biotic, while the dirt and minerals are abiotic.
Q3: Is the river part of the biotic or abiotic environment? Explain.
A3: It can be considered both. The algae, plants, and aquatic
organisms like fishes living in the river are biotic, while the water
and rocks of the river are abiotic.
Figure 18.5
Q1: Name two ways in which climate change affects the frequency
and severity of floods.
A1: Changes in rainfall patterns and melting ice can cause rivers
and lakes to overflow.
Q2: How has climate change caused a rise in sea level?
A2: Melting of glaciers and polar ice has caused sea levels to rise.Q3: Give an example of an environmental effect of climate change
in your state or region.A3: Answers may include drought or flooding.Figure 18.6
Q1: Why is it colder at the poles than at the equator?A1: The sun’s rays are spread wider at the poles and strike Earth
less directly than at the equator. Less direct sunlight = cooler.Q2: Why is it warmer at the equator than at the poles?A2: All of the sun’s energy is directed at the equator, and the rays
strike Earth at a direct angle there. The result is more intense heat
at the equator.Q3: During part of the year the Northern Hemisphere is tilted at a
more direct angle to the sun than the Southern Hemisphere is, and
for the other part of the year the opposite is true. How does this tilt
explain temperature differences in summer and winter?A3: When a hemisphere is tilted toward the sun, the sun’s rays
strike it more directly, causing the warmer temperatures of
summer. The opposite is true in the winter.Figure 18.7
Q1: How much of the incoming solar energy is reflected back to
outer space?A1: About a third.Q2: What kind of energy is reemitted to the atmosphere after
being absorbed by Earth’s surface?A2: Infrared radiation.Q3: How are greenhouse gases like a blanket on your bed at night?A3: Greenhouse gases absorb the heat around Earth and hold it
near the surface just as a blanket absorbs body heat, prevents it
from escaping, and holds it near your body.Figure 18.8
Q1: What measurements do the green circles represent?A1: The green circles indicate CO 2 levels measured from bubbles
of air trapped in ice that formed many hundreds of years ago.Q2: What measurements do the red circles represent?A2: The red circles are direct measurements of CO 2 levels at the
Mauna Loa Observatory in Hawaii.Q3: For approximately how many years has the Mauna Loa
Observatory been recording CO 2 levels?A3: Directly for about 60 years.Figure 18.9
Q1: In what years were global temperatures the lowest?A1: The years around 1910.Q2: In what years were global temperatures the highest?A2: The years around the late 1990s through the present.Q3: What trend is apparent in this graph of actual global
temperatures?A3: Average global temperatures are rising.