During the adaptive radiation of jawed fishes 400 million years ago, most cephalopods ________
a. lost their external shell and became active, quick, and relatively intelligent
b. evolved thicker, heavier shells requiring a sessile lifestyle
c. became herbivores, subsisting on algae and ocean plants
d. became extinct
a
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Animals that help other animals of the same species _____
A) have excess energy reserves B) are bigger and stronger than the other animals C) are usually related to the other animals helped D) are always male E) have defective genes controlling their behavior
Concerning the sex chromosomes, which of the
following is correct? a. The Y chromosome carries a greater number of genes for nonsexual traits than does the X. b. X and Y are different in size but carry nearly equal numbers of genes. c. The X chromosome carries more genes for nonsexual traits than does the Y. d. The X chromosome carries only gender-related genes. e. The X chromosome carries the SRY gene.
Which birth control method prevents sperm from exiting the male’s body?
a. rhythm method b. withdrawal c. vasectomy d. tubal ligation e. condom
Which type of base-pair substitution mutation has no effect on the amino acid sequence of a protein?
A) Missense mutation B) Nonsense mutation C) Silent mutation D) Frameshift mutation E) None of these choices