Which type of selection is occurring with the ?-globin gene?
The human ?-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.
A. stabilizing
B. directional
C. disruptive
D. balanced
E. negative
D. balanced
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Which of the following is not a general requirement for complex multicellular life?
A. Cells must retain a full range of functions, including reproduction. B. Cells must stick together. C. Cells must communicate with one another. D. Cells must participate in a network of genetic interactions that regulate cell division. E. All of these options are requirements for complex, multicellular life.
Which of the following does not pertain to helminths?
A. Parasitic worms B. Have organ systems C. Eggs and sperm used for reproduction D. Often alternate hosts in complex life cycles E. Members of Kingdom Protista
Anabolic-androgenic steroids
a. are synthetic forms of testosterone. b. are synthetic forms of estrogens. c. are used for treating early puberty. d. are natural variants of testosterone. e. are natural variants of estrogen.
What metric unit would be most appropriate for expressing the size of most viruses?
a. Nanometer b. Millimeter c. Micrometer d. Centimeter