Most pedigrees showing the hypothetical human trait show the following characteristics: Females are affected twice as frequently as males. Affected fathers may have affected daughters but never affected sons. Half the children of affected mothers and normal fathers are affected. What is the MOST likely mode of inheritance for this disorder?
A. X-linked dominant
B. X-linked recessive
C. Y-linked
D. autosomal dominant
E. autosomal recessive
Ans: A. X-linked dominant
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A. estradiol. B. testosterone. C. FSH. D. LH. E. progesterone.
If one strand of DNA is CGGTAC, then the complementary strand would be
A) GCCTAG. B) GCCAUC. C) TAACGT. D) GCCATG.
Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?
A) They have been geographically isolated from each other for a longer time. B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp. C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp. D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.
Angiosperms are the most successful terrestrial plants. Which of the following features is unique to them and helps account for their success?
A) wind pollination B) dominant gametophytes C) fruits enclosing seeds D) embryos enclosed within seed coats E) sperm cells without flagella