Context and question: Sometimes people of mixed African-American and Native American descent report having had elder family members withholding pertinent genealogical information. Tracing the genealogy of African Americans can be a very difficult process, as censuses did not identify slaves by name before the American Civil War, meaning that most African Americans did not appear by name in those records. In addition, many white fathers who used slave women sexually, even those in long-term relationships like Thomas Jefferson's with Sally Hemings, did not acknowledge their mixed-race slave children in records, so paternity was lost.
Who were not identified by name on the census before the civil war?
Answer: slaves
Context and question: A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.
A railway electrification system supplies power to trains and trams with an on-board what?
Answer: unanswerable
Context and question: The number of species of flowering plants is estimated to be in the range of 250,000 to 400,000. This compares to around 12,000 species of moss or 11,000 species of pteridophytes, showing that the flowering plants are much more diverse. The number of families in APG (1998) was 462. In APG II (2003) it is not settled; at maximum it is 457, but within this number there are 55 optional segregates, so that the minimum number of families in this system is 402. In APG III (2009) there are 415 families.
How many species of moss is there?
Answer:
12,000