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 genotypic frequency = 1:1
The phenotypic frequency = 1:1
Explanation:
Given that:
The allele → R = Red beetles
The allele → B = Blue beetles
Since the gene color shows a codominant allele
The Red Beetle = RR
The blue beetles will be = BB
The heterozygous beetle will be = RB
∴
The punnet square showing the crossing of RB × RR is:
R B
R RR RB
R RR RB
The result shows that we have two red beetles and two heterozygous beetles.
Hence;
The genotypic frequency = 1:1
The phenotypic frequency = 1:1
Answer:
3. the absence of a cell wall in human cells
Explanation:
Animal cells do not have cell walls. Cell membranes separate the cytoplasm of the animal cells from the surroundings and maintain their interior. Plant cells have cellulosic cell walls. A cell wall surrounds the cell membrane of a plant cell. Cell walls serve to provide structural support and protect plant cells from pathogens. Cell walls also help keep excess water out of cells so they do not burst. Therefore, human cheek cells would not have cell walls while the onion cells would have cell walls made up of cellulose.
Answer:
DNA
Explanation:
<h2>What is DNA?</h2>
DNA is a self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.
B it will be exactly 100 grams
