Two closely related nocturnal species of frogs in the same marsh sometimes mate, but the embryos almost always fail to complete development. The mechanism maintaining these frog species is __________.
a. reduced hybrid fertility
b. gametic isolation
c. reduced hybrid viability
d. temporal isolation
e. habitat isolation
Answer: c. reduced hybrid viability
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Imagine that you are searching for the gene associated with nail-patella syndrome, a dominant genetic disorder that causes developmental abnormalities. In a large pedigree you discover an association between nail-patella syndrome and a genetic marker that
occurs in two different alleles, A and B. Fifteen individuals within this pedigree have nail-patella syndrome and are A/B heterozygotes for the marker. Thirty individuals within this pedigree don't suffer from nail-patella syndrome and are homozygous for the A marker allele. One individual within this pedigree has nail-patella syndrome and is also homozygous for the A marker allele. The most likely explanation for this exceptional individual is that _____. A) a new mutation converted the disease-causing allele to the wild-type form B) a new mutation converted the B allele of the marker to the A form C) the exceptional nail-patella individual is haploid D) recombination occurred between the nail-patella gene and marker locus in one of the parents of the exceptional individual
If a fungus encountered a particularly rich food source, what would be the expected result?
A. Hyphae would branch and extend rapidly to form a mycelium. B. Hyphae would stop growing in length, but increase in diameter. C. Individual hyphae would begin to produce spores. D. Hyphae would stop growing and a fruiting body would form to exploit the food source. E. The mycelium would break down into widely separated hyphae.
The most numerous cells carried in the plasma
are
a. erythrocytes. b. leukocytes. c. platelets. d. thrombocytes. e. cyanocytes
Neisseria gonorrhoeae circumvents our iron-sequestering defenses by
A) breaking down red blood cells to get to the iron-rich hemoglobin inside. B) capturing our iron-binding proteins and pulling the iron out of them for their own use. C) making siderophores that pull iron from our iron-binding proteins. D) using manganese in their metal-requiring enzymes instead of iron. E) releasing lytic enzymes and then scavenging the debris for iron.