Practice Exam 2 - Environmental Science - page 267

2. A The production of electricity and transportation are the two main contributors to global emissions of
greenhouse gases. Fossil fuels power many electrical power plants and most forms of transportation,
both of which are increasing along with the human population.
3. D A tragedy of the commons is the overexploitation of a resource due to unregulated use, and the best
way to address this issue is through some form of regulation. This regulation can occur through private
ownership, government regulation, or a cooperative effort of participants involved in the use of the re-
source.
4. C Death rates fall during the transitional stage of demographic transition due to more efficient and reli-
able food production and medical advancements, which reduce death due to starvation and health-re-
lated causes.
5. C Water vapor is the most abundant greenhouse gas, considered as such because of its ability to absorb
reflected solar radiation that would otherwise escape into space.
6. A Radiation is released when temperatures in the core of the reactor increase and the uranium fuel rods
melt. Water is usually used as a way to keep the reactor core cool in a nuclear power plant. If the
coolant water is lost or leaks in some way, the core will quickly overheat, causing the melting of the
metal in which the uranium fuel rods are located. This allows radiation from the uranium to escape
from the core.
7. E Despite lower overall populations, industrialized nations use close to 100 percent more energy than
developing nations do. This is because people in industrialized nations use relatively large amounts of
energy for transportation; industry; and home heating, cooling, and lighting. Because industrialized na-
tions have the economic ability to consume in excess, they do, and this consumption is currently not
balanced by energy-saving technologies.
8. A Photochemical smog is produced when atmospheric nitrogen reacts with oxygen to produce nitric ox-
ide, which then combines with oxygen to form nitrogen dioxide. Nitrogen dioxide absorbs light energy
and splits to form nitric oxide and atomic oxygen. The oxygen atoms combine with the O 2 in air to pro-
duce ozone. Then nitric oxide can remove ozone by reacting with it to form nitrogen dioxide and oxy-
gen.
9. B Breeder nuclear reactors make more efficient use of the fuel than conventional nuclear reactors do.
This is because breeder reactors make use of the isotope U-238, which is discarded as a waste product
in conventional reactors.
10. A Polybrominated diphenyl ethers (PBDEs) are used as fire retardants in consumer products ranging
from computers and televisions to couches, curtains, and plastics. Unfortunately, PBDEs can be re-
leased when products are created and during disposal. PBDEs may cause cancer and neurological prob-
lems.
11. D A temperate deciduous forest is mainly comprised of deciduous trees, which are trees that lose their
leaves in the winter months.
12. B Invasive species thrive in a new environment because of the lack of limiting factors, including lack
of predators and disease, potentially abundant food sources, and the ability to outcompete native species
for resources.
13. B Hydrogen power uses electrolysis to split water molecules into their component parts of hydrogen
and oxygen. Although this process makes pure hydrogen without creating any harmful or polluting by-