Chapter 21 Section Review Answers
Environmental problems
1.nonrenewable resource
2.Biodiversity
3.D
4.B
5.A renewable resource is a resource that can be replaced as quickly as it is used. A nonrenewable resource cannot be replaced or can be replaced only over thousands or millions of years.
6.Sample answer: Advances in medicine, such as immunizations, and advances in farming have made human population growth possible.
7.An exotic species is a species that makes a home for itself in a new area outside its native home.
8.Sample answer: Habitat destruction may cause erosion and pollute streams and rivers. Habitat destruction may also leave some organisms without food or a place to live. Some of these organisms may die. So, habitat destruction causes the loss of biodiversity.
10.Sample answer: Hospitals save people’s lives but produce medical waste, which is hazardous waste. Old refrigerators kept food cold but used CFCs, which destroy protective ozone. Road construction makes it easier for people to travel from one place to another but causes habitat destruction.
11.Sample answer: Each person causes pollution. As the population grows, more pollution is produced.
12.Sample answer: Pollution of marine habitats could kill many of the organisms that humans collect for food or could make those organisms unfit for humans to eat. Pollution also harms coral reefs, which are places that people like to visit for recreation.
environmental solutions
1.Sample answer: Conservation protects the environment by reducing pollution. Someone who is recycling is conserving resources.
2.B
3.D
4.Sample answer: Reduce means “to use fewer natural resources.” Reuse means “to use something over and over.” Recycle means “to reclaim materials from waste.”
5.Sample answer: Biodiversity is important to the survival of species in an ecosystem. For example, the loss of a predator can cause an increase in a prey population that causes other species to starve. Biodiversity is protected by protecting species and by protecting habitats.
6.Sample answer: Liza reduced the use of resources by riding her bike, which saves gas; by buying products with little packaging, which reduces trash; and by using a backpack instead of a plastic bag, which also reduces trash.
7.Sample answer: Conserving resources means that you are using less of them, so you won’t be producing as much trash. If you conserve resources, fewer habitats will be destroyed by activities such as mining, harvesting, or construction.
8.27% (28% 2 14%; 13% 14% 27%)
9.18% (20% 0.9 18%)