The student correctly associates macrocytic and enlarged red blood cells with which type of anemia

Macrocytic and enlarged red blood cells are characteristic for macrocytic anemia.

Macrocytic anemia is a blood disorder which occurs when the body produce large red blood cells and not enough normal red blood cells. Macrocytic anemia is most often caused by a lack of vitamin B-12 and folate with the symptoms like loss of appetite or weight, pale skin (including lips and eyelids), brittle nails, diarrhea, fatigue…

The student correctly associates macrocytic and enlarged red blood cells with a type of anemia called a megaloblastic anemia. In this type of anemia, red blood cells (RBC’s) are not produced properly so the cells are very large. They are not able to withdrawal the bone marrow to come into the bloodstream and carry or transfer the oxygen.  

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

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