Weeds are types of
A) pathogens that spread disease to humans or between plants.
B) animals or plants that can cause disease.
C) plants that can rapidly spread through lightly airborne seeds.
D) pests that may threaten our health or compete with our food.
Question 2
The Millennium Ecosystem Assessment primarily characterized human impact on
A) atmospheric carbon dioxide levels.
B) degradation of the ozone layer.
C) ecosystem services.
D) plate tectonics.
