In order to understand human impact on the environment, scientists need to monitor the levels of many substances. which substances should be monitored and controlled to help minimize the impact of human activity on air quality A. nitrogen
B. water vapor
C. ozone
D. oxygen

In this case, the statement that people who exercise for an hour may have lower cholesterol levels is .

Many plants can reproduce asexually. which of these is an example of asexual reproduction in a plant? a. pine cones forming on a tree b. cross-pollination in a tomato c. roots sprouting from a potato d. night-blooming jasmine flowers

Vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a.) antibody, antibiotic b.) antigen, antibody c.)antibiotic, antibody d.)antibody, antigen