A woman who is herself a fraternal twin has what chance of giving birth to fraternal twins?
a. double
b. triple
c. quadruple
d. one half the average
e. about the same as the average
A
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E. coli has been isolated and cultured from three different individuals. Upon biochemical testing of these three cultures, you find that there are differences in some reactions. What is the best explanation of these differences?
A. These represent three different species of E. coli. B. This is normal genetic variation seen among strains of E. coli. C. The other two cultures are not really E. coli. D. Mistakes have been made in the test interpretation. E. Two of the cultures are mutants of the other.
If you cross RrYy and RRyy pea plants, what fraction of the offspring will have yellow peas? R = round, r = wrinkled, Y = yellow, y = green.
A. 100% B. 50% C. 75% D. 25% E. 0%
Which statement is NOT true?
a. Migration leads to genetic variation. b. Dominant genes always occur more frequently in a population than recessive genes. c. Nonrandom mating may result in changes in gene frequency. d. The Hardy-Weinberg law applies to large, stable populations. e. Crossing over increases variation.
Chloroplasts arose by endosymbiosis of ______.
A. an aerobic bacterium B. a photosynthetic bacterium C. an anaerobic bacterium D. an aerobic archaeon E. a photosynthetic archaeon