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>
By process of elimination you can find the right answer. We know for a fact that carbon is found in all living organisms. That is why we talk about carbon based life forms. So the first statement cannot be true. You can figure out how many Valence electrons an element has by looking at the group number. The group number of carbon is 4 so the 2nd statement cannot be true. We know that carbon does bond with other elements because it is not a noble gas and therefore must be able to form compounds.
This means the answer must be they can form up to four covalent bonds
First of all, pterophyta have neither seeds nor flowers in the first place.. Angiosperms are flowers and are the most diverse group of land plants so I doubt they would be losing its seeds... Lastly gymnosperms are a group of seed producing plants.. According to what I just wrote, what do you think the answer is??
