Which of the following features were required for the the evolution of the amphibians?
A. notochord, vertebrae, jaws, bony skeleton, lungs and 4 limbs
B. notochord, vertebrae, jaws, bony skeleton, lungs and amniotic eggs
C. notochord, mammary glands, jaws, bony skeleton, lungs and 4 limbs
D. notochord, vertebrae, jaws, cartilaginous skeleton, lungs and 4 limbs
Answer: A
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Marc Spehr and his colleagues demonstrated that ____
a. sperm cannot detect and swim toward attractant molecules b. sperm can detect and swim toward attractant molecules c. eggs release chemicals that attract sperm d. sperm attraction can be inhibited by chemicals e. sperm can release chemicals that kill other sperm
Which statement about prokaryotic gene expression is true?
a. RNA transcription and protein translation occur almost simultaneously. b. Gene expression is regulated primarily at the epigenetic level. c. Prokaryotic organisms have intracellular organelles. d. RNA post-processing includes the splicing of exons.
Prions differ from viroids in that they are
a. made up of DNA. b. circular RNA surrounded with protein. c. linear DNA surrounded with lipid. d. circular RNA with no protein coat. e. single proteins.
The force of the original vibrations entering the ear is amplified by the
a. organ of Corti. b. oval window. c. round window. d. Eustachian tube. e. semicircular canals.