Paleontologists estimate that ________
A) extinction is tied exclusively to human activities
B) more than 99% of all species alive today have been discovered and described
C) 99% of all species that have ever existed are now extinct
D) biodiversity is evenly spread over the earth's biomes
C
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Most of the earth's deserts are located in the:
A) boundary between liquid and frozen oceans. B) tradewind belt. C) doldrum belt. D) subsidence areas of subtropical highs. E) areas along the polar front.
Which of the following correctly describes the relationship between the R,S system and the +/- system associated with optically active compounds?
A) All R enantiomers are (+). B) All S enantiomers are (+). C) No S enantiomers are (+), but some R enantiomers are (-). D) There is no general relationship between the R,S designations and the +/- designations.
P-bromonitrobenzene is treated with hydrogen gas in the presence of a Pd catalyst. What would be the product of the reaction?
A) 4-bromoaniline B) benzene C) bromobenzene D) nitrobenzene
What makes up the greatest biomass of any species on Earth?
A) King crab B) Krill C) Squid D) Coral