The human immunodeficiency virus (HIV) that causes the disease known as aids selectively infects helper T cells (CD4+).
This retrovirus also infects macrophages and dendritic cells. When CD4+ T cell numbers decrease below a critical level (due to the killing of this cells with different mechanisms), cell-mediated immunity is lost. As a result, the body becomes progressively more susceptible to infections, leading to the development of AIDS.
<span> HIV can be transmitted only via body fluids like blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk, which means that people usually get or transmit HIV through sexual behaviours and use of the needle. For HIV infection, these fluids must come in direct contact with a mucous membrane or damaged tissue. Another way is to be directly injected into the bloodstream (from a needle for example).</span>
The 3 States Of Matter udndusjd
I believe the answer is : D
The genotype of the cross is 1 : 2 : 1 ( TT : Tt : tt )
The phenotype of the cross is 3 : 1 ( Tall : Dwarf )
<u>Explanation:</u>
Given:
Cross between two heterozygous tall pea plant
Let the allele of a tall pea plant be represented by T and for dwarf be t
In heterozygous condition, the genotype would be Tt
Cross between Tt X Tt is shown in the diagram inserted.
According to the cross performed:
The genotype of the cross is 1 : 2 : 1 ( TT : Tt : tt )
The phenotype of the cross is 3 : 1 ( Tall : Dwarf )
