Why is the ratio of male to female births roughly 50:50?
a. half of all sperm cells carry a Y chromosome
b. all eggs carry an X chromosome
c. half of all egg cells carry a Y chromosome
d. all sperm cells carry an X chromosome
Answer: a. half of all sperm cells carry a Y chromosome
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a. epididymis b. bulbourethral gland c. testis d. seminal vesicle e. ejaculatory duct
A type of tissue has tight junctions, a basement
membrane, no blood supply, and is one layer thick. This tissue type is
a. stratified epithelium. b. simple epithelium. c. connective. d. muscle. e. nervous
Which law of thermodynamics explains energy inputs and outputs in chemical reactions?
1.the first law of thermodynamics: energy cannot be created or destroyed
2.the second law of thermodynamics: energy tends to spread out spontaneously.
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A) endoskeleton B) notochord C) skull and a backbone D) pharyngeal slit