Why do we have fossils for only about 250,000 different species, although there must have been millions more species?
1.Fossils can form only if exposed to air, and most fossils are buried.
2.Fossils formed only where there were major disruptive geologic events, so they are relatively rare.
3.Fossils are found close to the surface so many have been destroyed by development.
4.Many ancient and extinct species were very soft, so did not fossilize well.
4
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Enzymes speed up reactions by
A. raising activation energy. B. producing heat. C. reducing entropy. D. lowering activation energy. E. raising activation energy AND reducing entropy.
___________, such as sea stars, are invertebrate
members of the deuterostome lineage. Fill in the blank(s) with the appropriate word(s).
Although they are two different types of connective tissue, cartilage and bone have what feature in common?
a. lacunae and Haversian canals b. canaliculi and Haversian canals c. lacunae and canaliculi d. lamellae only e. lacunae only
A scientist develops a new medication that is a protein compound and that must be administered by injection. Which of the following would be the most effective and safest means of preparing a sterile solution of the new medication?
A) autoclaving B) filtration C) dilution with alcohol D) lyophilization E) ultraviolet irradiation