Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: The Prokaryotic Cell Recall that prokaryotes (Figure 22.10) are unicellular organisms that lack organelles or other internal membrane-bound structures. Therefore, they do not have a nucleus but instead generally have a single chromosomea piece of circular, double-stranded DNA located in an area of the cell called the nucleoid. Most prokaryotes have a cell wall outside the plasma membrane. Answer: nucleoid
[EX A]: Prokaryotic cells do not have a nucleus but instead generally have a single chromosome, a piece of double-stranded dna located in an area of the cell called the what?

[EX Q]: Passage: Great volcanic explosions and glowing red rivers of lava are fascinating. All igneous rock comes from magma or lava. Remember that magma is molten rock that is below Earth's surface. Lava is molten rock at Earth's surface. Answer: magma or lava
[EX A]: Where does all igneous rock come from?

[EX Q]: Passage: HIV spreads through contact between an infected person's body fluids and another person's bloodstream or mucus membranes, which are found in the mouth, nose, and genital areas. Body fluids that may contain HIV are blood, semen, vaginal fluid, and breast milk. The virus can spread through sexual contact or shared drug needles. It can also spread from an infected mother to her baby during childbirth or breastfeeding. Saliva can carry the HIV virus, but it won't spread it, unless the saliva gets into the bloodstream. Other body fluids such as urine and sweat do not contain the virus. HIV does not spread in any fluid in which the host cells cannot survive. Answer: bloodstream
[EX A]:
Saliva can carry the hiv virus, but it won't spread it, unless the saliva gets into what?