Which of the following statements is NOT true?
a. Natural selection is based upon differential
reproduction and survival.
b. For evolution to occur in a population, there
must be some variation.
c. Most mutations have beneficial effects on traits.
d. A population evolves when heritable change
occurs in a line of descent.
e. Over time, some genetic traits are more adaptive
than others.
Answer: c
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Excess glucose taken up by the liver is converted to
a. fat. b. glycogen. c. bile salts. d. fructose. e. proteins.
Which one of the following pairings of an aneuploidy and the syndrome it causes is incorrectly
matched? A. X-chromosome monosomy (X and no Y) causes Turner syndrome. B. X-chromosome trisomy causes Klinefelter syndrome. C. Trisomy 21 causes Down syndrome. D. Trisomy 13 causes Edwards syndrome. E. Uniparental disomy causes Prader-Willi syndrome.
Lethal genes (genes that result in the failure to develop a vital organ or metabolic pathway) are nearly always recessive. Animal breeders who discover a unique trait and selectively breed to increase the occurrence of that trait often encounter a noticeable increase in lethal genes. Why?
A. "Pleiotropy"-the gene that is being selected for this trait may have the second effect of being lethal. B. The lethal recessive gene may be incompletely dominant. C. Spreading the gene among offspring of both sexes will increase the likelihood it will be sex-linked and expressed. D. "Epistasis"-selection for the desired trait may result in "uncovering" the lethal gene. E. The selective-mating of closely related individuals, or inbreeding, increases the chances that two recessive genes will "meet" in offspring.
Scattered patchy blue areas are seen on the Brown and Hopps gram stain although the decolorization step was prolonged. This is most likely the result of:
a) a section of uneven thickness b) drying of the section during the procedure c) inadequate mordanting of the section d) overtreatment with acetone