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>
Answer:
The correct answer is to ADP and Pi is the most common mechanism for transferring free energy to drive endergonic reactions.
Explanation:
Many endergonic reactions(the free energy change of these reactions are highly positive) proceed in a thermodynamically unfavorable manner.
To make those reactions thermodynamically favorable,these reactions are coupled with hydrolysis of high energy compound such as hydrolysis of ATP to ADP and Pi.
As a result the free energy change of those reactions becomes negative which allow those reactions to proceed in a thermodynamically favorable manner.
The answer is cotton. It is natural because it is grown and easily woven in to clothes :)
There are choices for this question namely:
<span>A) genetic bottleneck.
B) sexual selection.
C) habitat differentiation.
D) founder effect.
</span>
The correct answer is founder effect. The definition of founder effect is the loss of genetic variation when a new population is established in a small number of individuals from a larger population. The larger population in the context is the ecosystem in Hawaii before it rose from the sea surface. After it rose above the sea surface, most organisms will not be able to survive in land but there will be a small population that can evolve from there.
