Question

1. What alpha-globin genotype has the highest V_O2max when tested at high altitudes (3800m)?
   1. a⁰c⁰/a⁰c⁰
   2. a⁰c⁰/a¹c¹
   3. a¹c¹/a¹c¹

Answer 1

The correct answer is option A - a0c0/a0c0 .
The alpha-hemoglobin chains in adult deer mice are usually encoded by two tightly linked loci. Because of strong linkage disequilibrium, almost all alpha-globin haplotypes fall into just two classes. The a0c0 class predominates in high-altitude populations, whereas the a1c1 class is generally fixed in low-altitude populations . The a1c1/a1c1 genotype mice have the highest P50 values and show the highest Vo2max values at low altitude (340 m) but the lowest VO2max values at high altitude (3800 m). The a0c0/a0c0 mice have the lowest P50, and show the highest VO2max at high altitude but usually have the lowest VO2max at low altitude. The a0c0/a1c1 heterozygotes have an intermediate P50 and are generally intermediate in VO2max at both altitudes.