Mammals appeared 220 million years ago but did not begin to greatly diversify until 65 million years ago. Why is
this? What will be an ideal response?
ANSWER: During the first 155 million years of mammalian existence, they shared the Earth with
dinosaurs. Mammals were not able to directly compete, and thus stayed relatively small.
After the extinction of the dinosaurs, mammals evolved to fill the niches previously occupied
by the dinosaurs.
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Antiseptics are generally regulated by the
A. Food and Drug Administration. B. The National Institutes of Health. C. Centers for Disease Control and Prevention. D. Environmental Protection Agency.
Changes in the nucleotide sequence of DNA, known as _______ are the ultimate source of new alleles.
a. mediocre b. mutagens c. mutations d. metamorphosis e. metastasis
The ________ route of drug administration is commonly used for small laboratory animals such as the rat.
a. intraperitoneal b. oral c. intravascular d. topical e. intranasal
Protozoan cysts are resistant to many disinfection methods.
Answer the following statement true (T) or false (F)