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:
light
Explanation:
The above experiment is an investigation on the factors that affect photosynthesis which include carbon dioxide concentration,light intensity and quality,chlorophyll, water and temperature.Light was the independent variable. When the lant is moved to an area where light intensity is low, the rate of photosynthesis decreases.
After the experiment, oxygen gas is produced being a by-product of photosynthesis. Plants that are not adapted to an aquatic environment are not suitable for this experiment. The amount of carbon dioxide dissolved in water is low.
When insulin is deficient , GLUT4 transporters are not inserted into the cell membranes , glucose is not transported into the cells and the blood glucose concentration increases.
Insulin deficiency provides more amino acid and glycerol substrates for glucose synthesis ie increased gluconeogenesis .
With a deficiency of insulin, there is both increased hepatic glucose production through increased glycogenolysis and gluconeogenesis as well as decreased glucose use. The result is hyperglycemia.
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Answer:
The fish did not yet exist when the old layers of rocks were deposited. In fact, animals with hard parts did not evolve until about 600 million years ago, which is only about 13% of the 4.5 billion year age of the Earth. Multicellular animals without hard parts left tracks in older sediments, but had no fossilize-able body parts.
Explanation: