The human b-globin gene has two alleles, HS and HA, individuals that are homozygous for HS have sickle-cell anemia and a lower fitness. Individuals that are heterozygotes (HSHA) do not show sickle-cell symptoms and have a resistance to malaria. Individuals that are homozygous for HA have the highest fitness but are susceptible to malaria. In areas where malaria is prevalent the HS allele is maintained in the population. Which type of selection is occurring with the b-globin gene?
A. stabilizing
B. directional
C. disruptive
D. balanced
E. negative frequency dependent
D. balanced
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A __________ is a hybrid, with two nonidentical
alleles (Aa). Fill in the blank(s) with the appropriate word(s).
You have inherited some old glass baby milk bottles from your grandmother, and you would like to use them instead of plastic bottles. The bottles are placed into a large metal container and placed in the oven at 325°F for about 2 hours. What factor would you change if you wanted the sterilization to occur much quicker?
A. Increase the temperature of the oven by 5 degrees B. Use a pressure cooker to sterilize the bottles with steam C. Place the bottles outside in the sunlight and then place in the oven D. Pour an antimicrobial chemical into the bottles before placing into the oven
Extinct jawless fish include the:a
lungfish. b. lancelets. c. placoderms. d. acanthodians. e. ostracoderms.
The length of time it takes for the cells labeled during DNA synthesis to begin to enter mitosis is a good estimate of the length of the _______ phase(s).
a. G1 b. S c. G2 d. M