Essential genes are the set of genes thought to be critical for an organism's survival. This definition assumes the abundant availability of all relevant nutrients and the absence of environmental stress. Only a small portion of an organism's genes are essential. In bacteria, an estimated 250400 genes are essential for Escherichia coli and Bacillus subtilis, which is less than 10% of their genes. Half of these genes are orthologs in both organisms and are largely involved in protein synthesis. In the budding yeast Saccharomyces cerevisiae the number of essential genes is slightly higher, at 1000 genes (~20% of their genes). Although the number is more difficult to measure in higher eukaryotes, mice and humans are estimated to have around 2000 essential genes (~10% of their genes).
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What does the definition of essential genes assume an absence of?
Ah, so.. environmental stress

Ethnic Russians constitute 25.5% of the country's current population and 58.6% of the native Estonian population is also able to speak Russian. In all, 67.8% of Estonia's population can speak Russian. Command of Russian language, however, is rapidly decreasing among younger Estonians (primarily being replaced by the command of English). For example, if 53% of ethnic Estonians between 15 and 19 claim to speak some Russian, then among the 10- to 14-year-old group, command of Russian has fallen to 19% (which is about one-third the percentage of those who claim to have command of English in the same age group).
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What percentage of Russians are between 15 and 19?
Ah, so.. unanswerable

Black labor played a crucial role in Miami's early development. During the beginning of the 20th century, migrants from the Bahamas and African-Americans constituted 40 percent of the city's population. Whatever their role in the city's growth, their community's growth was limited to a small space. When landlords began to rent homes to African-Americans in neighborhoods close to Avenue J (what would later become NW Fifth Avenue), a gang of white man with torches visited the renting families and warned them to move or be bombed.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What was NW Fourth Avenue previously called?
Ah, so..
unanswerable