Select the correct statement regarding the greatest extinction event in earths h

Question

Select the correct statement regarding the greatest extinction event in earths history

a)It occurred 10,000 years ago at the end of the last major glaciation

b)65.5 million years ago when the dinosaurs went extinct from a giant meteor

c)It occurred 251 MYA when massive volcanism caused the Siberian traps

d)542 million years ago during the Cambrian explosion.

e)It occurred during the great oxygen catastrophe

Walking along the beach , you find animal with radial symmetry and two germ layers, it is most likely

a)A bilateran

b)A mollusk

c)A cnidarian

d)An arthropod

e)A chordate

Explanation / Answer

1. C    There have been five mass extinction events in Earth's history. In the worst one, 250 million years ago, 96 percent of marine species and 70 percent of land species died off.

2. C   Animals with radial symmetry, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic.

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