People homozygous for the sickle-cell anemia allele develop a life-threatening disease, while those homozygous for the normal allele are at the highest risk of dying from malaria. Carriers have some resistance to malaria but do not develop sickle cell anemia. This is an example of
A. genetic bottleneck.
B. heterozygote advantage.
C. point mutation.
D. heterozygosity.
E. founder effect.
Answer: B
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Helicase ________.
A. supercoils DNA B. unwinds RNA C. winds RNA D. unwinds DNA
Four of the five answers below are correct statements about seedless vascular plants. Select the exception
a. Sporophytes are independent of gametophytes. b. Water is not needed for gamete transport. c. Sporophytes have vascular tissue. d. Seeds are not produced. e. Living members still exist.
Assume that a species has a diploid chromosome number of 24. The term applied to an individual with 25 chromosomes would be ________
A) euploid B) triploid C) trisomy D) aneuploidy E) aneuploidy and trisomy
What is the main function of the nucleolus?
A) It produces enzymes that are then exported to the lysosomes. B) It produces cell adhesion proteins that are then exported to the cell membrane. C) It is the site of ribosome-subunit synthesis. D) It is the site of photosynthesis in photosynthetic cells. E) It is the site of cellular waste digestion and recycling.