Problem: Flowering plant:

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.

What is the estimated range for the number of flowering plants?
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A: 250,000 to 400,000


Problem: Bird migration:

In the tropics there is little variation in the length of day throughout the year, and it is always warm enough for a food supply, but altitudinal migration occurs in some tropical birds. There is evidence that this enables the migrants to obtain more of their preferred foods such as fruits.

Why does altitudinal migration occur in some tropical birds?
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A: to obtain more of their preferred foods


Problem: Incandescent light bulb:

The spectrum emitted by a blackbody radiator at temperatures of incandescent bulbs does not match the sensitivity characteristics of the human eye; the light emitted does not appear white, and most is not in the range of wavelengths at which the eye is most sensitive. Tungsten filaments radiate mostly infrared radiation at temperatures where they remain solid – below 3,695 K (3,422 °C; 6,191 °F). Donald L. Klipstein explains it this way: "An ideal thermal radiator produces visible light most efficiently at temperatures around 6,300 °C (6,600 K; 11,400 °F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous efficacy (LER) is 95 lumens per watt." No known material can be used as a filament at this ideal temperature, which is hotter than the sun's surface. An upper limit for incandescent lamp luminous efficacy (LER) is around 52 lumens per watt, the theoretical value emitted by tungsten at its melting point.

What is the flaw in the color of light produced by an incandescent bulb?
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A: the light emitted does not appear white,


Problem: Hanover:

Another point of interest is the Old Town. In the centre are the large Marktkirche (Church St. Georgii et Jacobi, preaching venue of the bishop of the Lutheran Landeskirche Hannovers) and the Old Town Hall. Nearby are the Leibniz House, the Nolte House, and the Beguine Tower. A very nice quarter of the Old Town is the Kreuz-Church-Quarter around the Kreuz Church with many nice little lanes. Nearby is the old royal sports hall, now called the Ballhof theatre. On the edge of the Old Town are the Market Hall, the Leine Palace, and the ruin of the Aegidien Church which is now a monument to the victims of war and violence. Through the Marstall Gate you arrive at the bank of the river Leine, where the world-famous Nanas of Niki de Saint-Phalle are located. They are part of the Mile of Sculptures, which starts from Trammplatz, leads along the river bank, crosses Königsworther Square, and ends at the entrance of the Georgengarten. Near the Old Town is the district of Calenberger Neustadt where the Catholic Basilica Minor of St. Clemens, the Reformed Church and the Lutheran Neustädter Hof- und Stadtkirche St. Johannis are located.

What world famous landmark is located on the bank of the Leine?
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A:
Nanas of Niki de Saint-Phalle