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 tributaries carry small amounts of salt into the lake
<u>Explanation</u>:
The Greatest salt lake is one of the most saline inland water body in the world.The water carried to this lake by the tributaries is very less as compared to the amount of the salt present in the lake. Rest part of the salt remains in the lake as such.
When the water from the lake gets evaporated, it leaves behind the salt. When time passes by, or years of inflow and evaporation salts they gets deposited layer over layer. The amount of salt added leads to formation of new minerals on the sea floor.
Answer:
Nomad
Explanation:
is a person or group of people without a designated home who roam around in search of food and pasture land. A person who moves from place to place without having a permanent home is an example of anomad.
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Answer:
The correct answer is B. Worms move through changes in body structure caused by contraction of muscles compressing their watery fluid.
Explanation:
The hydroskeleton consists of a fluid-filled cavity, surrounded by muscles. The fluid pressure and the action of the muscles that border it, serve to change the body's shape and produce a movement such as digging or swimming. The successive contraction of various metamers, which are provided with bundles of circular and longitudinal muscle fibers, stretching and thickening parts of the body, allow it to move horizontally. Hydrostatic skeletons have a role in the locomotion of annelids, nematodes and other invertebrates. The hydroskeleton has similarities with the hydrostatic muscles.
Answer: The genes have a codominant pattern of inheritance because the heterozygous forms both traits equally.
Explanation: