Triiodothyronine (T3) is secreted by
a. pancreatic islet cells.
b. the thyroid gland.
c. the pituitary gland.
d. the adrenal medulla.
e. the adrenal cortex.
B
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What would happen to the HS allele if a vaccine for malaria was 100% effective?
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. . The HS allele would increase in frequency in populations where malaria was present. B. The HS allele would decrease in frequency in populations where malaria was present. C. There would be no change in frequency between the HS and HA allele. D. Negative frequency-dependent selection would occur and there would be a balanced frequency between the two alleles. E. The frequency of homozygous individuals would decrease and the heterozygous individuals would increase.
When a person receives a sudden, large dose of ionizing radiation, what symptoms may be expected to
occur? a. serious infections b. intestinal hemorrhages c. anemia d. wounds that do not heal e. all of these
In most species the expression of Hox genes is colinear with the anterior to posterior organization of the organism. Describe what this means
What will be an ideal response?
The preserved remains or physical evidence of an organism that lived in the past are called -
a. evolutionary features b. fossils c. mutations d. variations