Answer:
<em>6</em><em> </em><em>minutes</em>
EXPLANATION:
The brain can survive for up to about six minutes after the heart stops. The reason to learn cardiopulmonary resuscitation (CPR) is that if CPR is started within six minutes of cardiac arrest, the brain may survive the lack of oxygen. After about six minutes without CPR, however, the brain begins to die.
I think two are stem cell research and cloning
This excerpt outlines the important precedent set by the court case Plessy vs. Ferguson. Plessy vs. Ferguson establishes the idea that "separate but equal" facilities are constitutional (aka legal). Essentially, this Supreme Court ruling allows for private and public places to be segregated. The ruling of Plessy vs. Ferguson resulted in segregated facilities all over the country including schools, restauraunts, bus stops, bathrooms, water fountains, etc.
This case is not overturned until 1954, in which the case Brown vs. Board reverses this idea and declares that separate but equal facilities violates the 14th amednment rights of African-American citizens.
Smooth ER<span> also regulates and releases calcium ions and processes toxins. It is described as '</span>smooth<span>' to distinguish it from rough </span>ER<span>, which has ribosomes for protein synthesis on its surface. Each organelle in the cytoplasm of a cell is responsible for performing a certain function.</span>