Refer to the graph. The IUCN has so far assessed 53,033 species, of the approximately 8.7 million thought to exist on Earth.The graph shows the number of species in each extinction risk category that so far have been assessed.This suggests that, especially in nonvertebrate categories, such as corals, the numbers shown on the graph are likely to be
A) very accurate, because they have been comprehensively assessed.
B) fairly accurate, because even good estimates are subject to some errors.
C) underestimated, because only a small percentage of species have been assessed.
D) underestimated, because there is no valid way to assess aquatic species such as corals.
E) overestimated, because scientists tend to assess invertebrates more closely than vertebrates.

Question

Refer to the graph.  The IUCN has so far assessed 53,033 species, of the approximately 8.7 million thought to exist on Earth.The graph shows the number of species in each extinction risk category that so far have been assessed.This suggests that, especially in nonvertebrate categories, such as corals, the numbers shown on the graph are likely to be
A) very accurate, because they have been comprehensively assessed. 
B) fairly accurate, because even good estimates are subject to some errors. 
C) underestimated, because only a small percentage of species have been assessed. 
D) underestimated, because there is no valid way to assess aquatic species such as corals. 
E) overestimated, because scientists tend to assess invertebrates more closely than vertebrates.

Quizplus · Accepted Answer

The graph shows the number of species in each extinction risk category that have been assessed by IUCN. This suggests that only a small percentage of species have been assessed so far. Therefore, the numbers shown on the graph are likely to be underestimated, especially in nonvertebrate categories, such as corals.

Refer to the Graph