Unformatted text preview: ividuals homozygous for the
sickle cell trait, and 2pq is the percentage of homozygous individuals. 2pq = 2 x 0.88 x 0.12
77. D. Answers A, B and C all would likely occur if malaria was widespread disease in the US.
Answer D, however, is not a logical outcome of increased malaria incidence because the
mosquitoes are simply the transmission vectors of the disease and are not affected by it
positively or negatively. Page 9 of 12 78. B. Global warming could increase the number of malaria occurrences because an increase in
the mosquito population, the transmission vector of malaria, could increase the infection rates
of malaria. Mosquitoes breed in warm, wet environments, the number of which would be
increased by global warming.
79. D. She is not the mother. She can contribute only the i allele, and this child must receive iA
from one parent and iB from the other parent. The man cannot be ruled out as the father with
the limited information given, since he can contribute a iB allele to the child.
80. D. If the man previously fathered a child with blood type O, then the man must be of
genotype iBi. The woman can contribute only the O gene. Since the man has an equal chance
of contributing the i or iB allele, there is a 50% chance of the child being type O (genotype ii)
or type B (iBi).
81. B. Because the man in question 76 fathered a child of blood type O, he must be capable of
passing on the i allele, and therefore must be of genotype iBi.
82. B. Because the genes are so close in proximity, it follows that they are on the same
chromosome and will be inherited as a unit. The affected type AB man (genotype iaiB Nn)
had a type A affected mother (genotype iAi Nn) and a normal type B father (iBi nn)
reproduces with a normal type O woman (ii nn), their children have four possible genotypes:
iAi nn, iAi Nn, iBi nn, and iBi Nn. Therefore the chances of a normal child of type B blood is 1
in 4 or 25%.
83. D. People with blood type O are known an universal donors because their blood contains
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