2.3

Question 1

Pesticides

Answer 1

chemicals used to eliminate pests, such as insecticides that kill insects and
herbicides that kill weeds.

Question 2

Bioaccumulation

Answer 2

the gradual build-up of these chemicals in living

organisms

Question 3

Keystone species

Answer 3

species that can greatly affect population numbers and the health of an ecosystem. Salmon
are a keystone species in many British Columbia forest ecosystems get eating and polute the streams

Question 4

Biomagnification

Answer 4

s the process in which chemicals not only

accumulate but become more concentrated at each trophic level

Question 5

PCBs (polychlorinated biphenyls

Answer 5

synthetic chemicals that were widely used
from the 1930s to the 1970s in industrial
products such as heat exchange fluids, paints,
plastics, and lubricants for electrical
transformers. In 1977, they were banned in
North America as concerns grew about their
impact on the environment and human
health.

Question 6

Half-life is

Answer 6

the time it takes for the amount of a substance to decrease by half

Question 7

persistent organic

pollutants

Answer 7

PCBs belong to a class of compounds. POPs are carbon-containing compounds that remain
in water and soil for many years

Question 8

DDT

Answer 8

DDT was introduced in 1941 to
control disease-carrying mosquitoes. Although now banned in many countries because it biomagnifies, it has a long half-life and persists in the environment.

Question 9

parts per million (ppm).

Answer 9

One ppm means one particle of a given substance

mixed with 999 999 other particles

Question 10

Heavy metals

Answer 10

metallic elements with a high density that are toxic to

organisms at low concentrations

Question 11

Bioremediation

Answer 11

living things to clean up toxins.