After hundreds or even thousands of generations both alleles for sickle cell anemia are still common in those of African ancestry. This is supported by two mechanisms: heterozygote advantage and gene flow.
Heterozygote advantage
When an allele is said to be heterozygous, it is carrying one copy of a gene. For example if one carries a copy of sickle cell allele, it will stay in the population even after many generations — natural selection will not be able to remove it and it will be passed on through generations. So, having one copy of that allele is advantageous but not deleterious.
Gene flow
With humans migrating throughout the different parts of the world, sickle cell allele is passed from one person to another or in different populations. It is actually advantageous to have one copy of this allele especially if there’s malaria in the area, which the allele is resistant.
The existence of brain areas like Wernicke's and Broca's areas support Noam Chomsky's beliefs about language development.
Noam Chomsky is well known for his work on linguistics, especially, the evolution of transformational grammar. He presumed that formal grammar was directly accountable for an individual's capacity to comprehend and interpret basic pronouncements.
The Wernicke's Area is the region of the brain critical to language development. It is situated in the temporal lobe on the left hemisphere of the brain. Its functions involve language comprehension, semantic or grammar processing, language identification as well as language interpretation.
The Broca's area helps create speech sounds, whereas, the Wernicke's area contributes to comprehension of language.
To learn more about Broca's area here
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<span>The appropriate justification of this is that B. As hydrilla is aquatic in nature, the roots do not have to search for minerals, and there is no need for xylem to absorb nutrients because the plant is surrounded by water that has dissolved nutrients in it. </span>
The correct answer is letter a, it is because in wet drop method, it does not need to add water after placing the specimen because adding water before placing the specimen in the glass slide is already enough and after placing the specimen, a cover slip is the last step in finishing the method. That is why Johnny is not correct in doing the procedure.
