Ans.
Sickle-cell disorder shows defected red blood cells, due to mutation in gene that code for hemoglobin. The mutated genes for sickle-cell disease are found in higher percentage of sub-Saharan African population as it provides protection against malaria as compared to population of United States.
Malaria is common in sub-Saharan Africa region and there, natural selection favored gene for sickle cells, because it might be beneficial to people having sickle cell disease that makes them able to survive in such condition and transmit their genes to offspring.
On the other hand, in those Africans, who moved to United States, where malaria is uncommon or absent, natural selection favored normal, wild type genes, resulting in fewer people with defected sickle cell.
Thus, the evolutionary process behind this is 'natural selection.'
Answer:
Statements thar are true:
Some organisms have phenotypes that make them better increase chances of reproduction.
Natural selection continues to occur even today
Phenotypes found In the most successful members of a species become the most prevalent after several generations.
Explanation:
It is not true that all organisms must compete for survival, sometimes the conditions are good and there is enough food or good climate conditions and that makes no need of competition an increase in the individuals of the species.
Animals undergo natural selection, this is a random natural phenomenon that can make plants and animals adapt better or worse to the enviromental conditions. This cause that the beneficiaries can adapt, survive and reproduce and became the most prevalent after generations.
Mutations are not phenomen that occur because the living being needs it, but rather they are phenomenon that occur at random at any time and determine the possibility of survival.
A decrease in food availability will do the contrary, decrease the variation in a population because it makes that only those who manage to adapt to eat another food survive, for example.
Let us assign the
recessive allele for freckle to be f and
the dominant F. According to the statement, we deduce that ff = 0.04.
The frequency of the recessive f allele is, therefore, is
0.2 (square root of 0.04 ).
Hardy-Weinburg p + q = 1
P + 0.2 = 1; p = 1- 0.2 = 0.8
Therefore using the Hardy-Weinburg equation of a population
in equilibrium
P2+2pq+q2=1
Heterozygous individuals are;
2pq = 2*0.8*0.2 = 0.32
This is 32% of the population
Scientists have suggested that these examples of gigantism are possible because of the extreme cold found in these waters.
