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>
3% of time or, 40 minutes.
I hope this helped you answer your question! I've definitely learned a lot about the topic of meiosis and mitosis today from my research! Peace out!
- hershy103
A. <span>Exposure to an antigen
Exposure to viruses and antigens led to the foundation of modern vaccination. Vaccination introduces an antigenic material that helps the ability of the immune system to adapt a specific pathogen, therefore leading to a long-term immunity.</span>
This is to prevent water loss by the trees. Under drought or dry conditions, plants may close their stomata to limit the amount of water that evaporates from their leaves a process called transpiration. In this process water diffuses through the stomata into the atmosphere, in a bid to preserve water plants may close their stomata, especially during very dry climates.
Answer:
Rats - Virgin Island
Hemlock - Asia
Zebra moulds - Great Lakes
Explanation:
An alien species is one that was introduced into a new environment, but does not have harmful effects. Such alien species are considered invasive species as they begin to have harmful effects on the new habitat. Invasive species can cause damage to the ecosystem, economic harm or human health effects.
Three invasive species are as following:
- Rats that came on board ships to the Virgin Islands infested the islands' sugar cane fields and caused significant crop damage.
- The woolly adelgid hemlock is an invasive Asian insect which rapidly kills infested hemlock trees.
- Zebra moulds in the Great Lakes can easily cover submerged surfaces, obstructing water intakes at water treatment plants and power plants
