G6PD deficiency is an inherited condition in which the body doesn't have enough of the enzyme glucose-6-phosphate dehydrogenase, or G6PD, which helps red blood cells (RBCs) function normally. G6PD deficiency is most common in African-American males. Many females are carriers. It is known that Africa and the Mediterranean basin are high-risk areas for the infectious disease malaria. Researchers have found evidence that the parasite that causes malaria does not survive well in G6PD-deficient cells. How can you explain this?
A. Natural selection favors G6PD deficiency as compared to malaria.
B. Genetic drift is responsible for greater occurrence of G6PD deficiency in these regions.
C. Somatic mutations lead to G6PD deficiency in malaria-inflicted regions.
A. Natural selection favors G6PD deficiency as compared to malaria.
B. Genetic drift is responsible for greater occurrence of G6PD deficiency in these regions.
C. Somatic mutations lead to G6PD deficiency in malaria-inflicted regions.
-
I. Somatic mutations imply that the changes happened to the regular body cells as opposed to gametic mutations, which, of course, affect the gametes. Because the scenario states that the deficiency is most common in African-American males (i.e. homozygous) and many females are carriers (i.e. heterozygous), it is reasonable to assume that the condition itself is a recessive sex-linked trait that occurs on the X chromosome. Therefore, the mutation could not have happened on somatic cell as:
-- a) G6PD deficiency would not be passed on and
-- b) G6PD deficiency is a sex-linked genetic disorder.
This effectively rules out choice C.
II. Since it is known that Africa and the Mediterranean basin are high-risk areas for the infectious disease malaria, and that G6PD deficiency effectively combats it as well as relatively abundant in such areas, we can conclude that the deficiency may have developed as a protection to such stimuli rather than at random.
Therefore, we can cross out choice B, as genetic drift does not work to produce adaptations and is run by chance (i.e. the genes which survive as a result of genetic drift are not 'fit' but rather 'lucky').
III. By process of elimination, the only reasonable choice is C -- by the favour of natural selection. As opposed to genetic drift, natural selection is a mechanism run entirely by fitness, whereby the most advantageous traits are preferred and passed on, while the least advantageous traits reproduce less and ultimately do not survive. Since G6PD deficiency is advantageous in the sense that it protects against malaria, we can assume that natural selection favours it more than the parasitical disease.
Answer: A
-- a) G6PD deficiency would not be passed on and
-- b) G6PD deficiency is a sex-linked genetic disorder.
This effectively rules out choice C.
II. Since it is known that Africa and the Mediterranean basin are high-risk areas for the infectious disease malaria, and that G6PD deficiency effectively combats it as well as relatively abundant in such areas, we can conclude that the deficiency may have developed as a protection to such stimuli rather than at random.
Therefore, we can cross out choice B, as genetic drift does not work to produce adaptations and is run by chance (i.e. the genes which survive as a result of genetic drift are not 'fit' but rather 'lucky').
III. By process of elimination, the only reasonable choice is C -- by the favour of natural selection. As opposed to genetic drift, natural selection is a mechanism run entirely by fitness, whereby the most advantageous traits are preferred and passed on, while the least advantageous traits reproduce less and ultimately do not survive. Since G6PD deficiency is advantageous in the sense that it protects against malaria, we can assume that natural selection favours it more than the parasitical disease.
Answer: A
-
We conducted an experiment that investigate the uptake of sulfate ions by barley plants when exposed to low oxygen Answers content. Click here for the Full Disclaimer. Help us improve Yahoo!