A man is considered clinically infertile if his sperm concentration falls below:
a. 400 million/mL of semen
b. 165 million/mL of semen
c. 100 million/mL of semen
d. 60 million/mL of semen
e. 20 million/mL of semen
e
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Which statement describes cytoplasmic vesicles?
A) They are formed by all types of endocytosis. B) They have a membrane that is very different from the plasmalemma. C) They never contain extracellular fluids. D) They only contain solids. E) Contents are toxic to the cell.
Describe the role of nonshivering thermogenesis in regulating body temperature
A) Nonshivering thermogenesis involves the contractions of skeletal muscles to increase the generation of heat. B) Nonshivering thermogenesis involves the contraction of erector pili to retain heat. C) Nonshivering thermogenesis involves the release of hormones that increase cellular metabolic activity to generate heat. D) Nonshivering thermogenesis involves the activation of the parasympathetic nervous system to increase digestion to generate heat. E) Nonshivering thermogenesis involves vasoconstriction of blood vessels to reduce heat loss.
Neural tissue develops in the embryo from a portion of the
A. ectoderm. B. endoderm. C. mesoderm.
The thymus enlarges after puberty
Indicate whether the statement is true or false