Answer:
B) Viruses are killing some of his B cells and becoming incorporated into the genomes of others.
Explanation:
Epstein-Barr virus causes infectious mononucleosis by following mechanism.
1) Epstein-Barr virus attaches to and infects epithelium of the throat where it replicates and causes pharyngitis.
2) Virions enter the lymphoid vessels and are carried to the lymph nodes. Some virions escape the lymphnode trap and are carried to the bloodstream.
3) Virions attach specifically to B lymphocytes and infect them, producing either latent infection or productive infection.
4)The infected B lymphocytes actively replicate and differentiate into cells producing random immunoglobulins.
5)T cells respond to infection and destroy the lymphocytes replicating EBV vitus.
6) Latently infected B lymphocytes become immortal. They are not attacked by T cells.
Answer:
C) The stems would wilt.
Explanation:
The stem relies on the pressure of the plant cells to maintain its rigidity. The plant cells shrink when they lose water, losing their rigidness in the process.
Ans.
Sickle-cell disorder is a genetic disorder, which shows defected red blood cells, due to mutation in the genes for hemoglobin protein.
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.
Hence, sub-Saharan African population shows higher percentage of mutated gene for sickle cell as compared to population of United States.
Thus, the evolutionary process behind this difference is 'natural selection.'
I'm fairly sure it would be windward and leeward. So C
