Why might the knoblike proteins on the outer surface of hiv hold a key to the production of a vaccine against aids?

This is because the GP120 protein of the HIV virus that forms the ‘knob’ is essential for the infection of CD4 cells of the immune system by the virus. The glycoprotein is, therefore, a good target for vaccines especially since the molecule is highly conserved because most mutations in the region could be highly deleterious to the virus.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.

the farther away the object is from the central star (the sun) it's gravitainal pull on the object is weaker when it is farther

explanation: