Although Many Groups Continue to Contain Undescribed Members, Scientists Have

Q31: How can the significance of human involvement

Q32: Ecosystems that are not diverse tend to

Q33: More than half of the presently identified

Q34: Although water treatment facilities exist, in most

Q35: Many yet unknown species of insects are

Q37: Scientists estimate that about 90 percent of

Q38: During the past 30 years amphibians have

Q39: Studies have shown that when an ecosystem's

Q40: The end of the Permian period approximately

Q41: Functioning ecosystems provide a variety of benefits