Why will discharge of sewage wastes into lakes and rivers having abundant varieties of fish eventually eliminate much of the diversity of fish? a.) the amount of oxygen available will be markedly reduced. b.) the waters will become turbid (cloudy), making it difficult for the fish to find their prey. c.) the waters will be excessively heated with thermal pollution. d.) the number of spots where fish can lay their eggs will be reduced.

Which greenhouse gas is emitted when burn fossil fuels for energy? a.nitrogen b.oxygen c.carbon dioxide d.helium

Refer to this portion of a dichotomous key for fish identification to answer the question. 1. (a) has a single dorsal fin ® 5 (b) has a double dorsal fin ® 2 2. (a) one fin is spiny, the other is smooth ® 3 (b) one fin is not spiny or smooth ® 4 5. (a) has small fin on back near tail ® 6 (b) has no fin on back near tail ® 7 6. (a) has barbs near the mouth ® catfish (b) does not have barbs near the mouth ® 10 7. (a) tail is asymmetrical ® 8 (b) tail is symmetrical ® 9 10. (a) scales are small ® trout (b) scales are large ® whitefish what is the next step to complete to identify a fish that has a single dorsal fin, no fin on the back near the tail, and no barbs near the mouth? step 2 step 5 step 7 step 10

Physical characteristics of down syndrome