Article: Predators may increase the biodiversity of communities by preventing a single species from becoming dominant. Such predators are known as keystone species and may have a profound influence on the balance of organisms in a particular ecosystem. Introduction or removal of this predator, or changes in its population density, can have drastic cascading effects on the equilibrium of many other populations in the ecosystem. For example, grazers of a grassland may prevent a single dominant species from taking over.

Question: What changes to a keystone predator can seriously affect an ecosystem's equilibrium?
Ans: Introduction or removal of this predator, or changes in its population density


Article: The last opus number that Chopin himself used was 65, allocated to the Cello Sonata in G minor. He expressed a deathbed wish that all his unpublished manuscripts be destroyed. At the request of the composer's mother and sisters, however, his musical executor Julian Fontana selected 23 unpublished piano pieces and grouped them into eight further opus numbers (Opp. 66–73), published in 1855. In 1857, 17 Polish songs that Chopin wrote at various stages of his life were collected and published as Op. 74, though their order within the opus did not reflect the order of composition.

Question: Who grouped 23 unpublished pieces and published them as Opp. 66-73 in 1855?
Ans: Julian Fontana


Article: The most innovative period of Cubism was before 1914. After World War I, with the support given by the dealer Léonce Rosenberg, Cubism returned as a central issue for artists, and continued as such until the mid-1920s when its avant-garde status was rendered questionable by the emergence of geometric abstraction and Surrealism in Paris. Many Cubists, including Picasso, Braque, Gris, Léger, Gleizes, and Metzinger, while developing other styles, returned periodically to Cubism, even well after 1925. Cubism reemerged during the 1920s and the 1930s in the work of the American Stuart Davis and the Englishman Ben Nicholson. In France, however, Cubism experienced a decline beginning in about 1925. Léonce Rosenberg exhibited not only the artists stranded by Kahnweiler’s exile but others including Laurens, Lipchitz, Metzinger, Gleizes, Csaky, Herbin and Severini. In 1918 Rosenberg presented a series of Cubist exhibitions at his Galerie de l’Effort Moderne in Paris. Attempts were made by Louis Vauxcelles to claim that Cubism was dead, but these exhibitions, along with a well-organized Cubist show at the 1920 Salon des Indépendants and a revival of the Salon de la Section d’Or in the same year, demonstrated it was still alive.

Question: In which city did Galerie de l’Effort Moderne take place? 
Ans: Paris


Article: However, the problem of deflection settings — 'aim-off' — required knowing the rate of change in the target's position. Both France and UK introduced tachymetric devices to track targets and produce vertical and horizontal deflection angles. The French Brocq system was electrical, the operator entered the target range and had displays at guns; it was used with their 75 mm. The British Wilson-Dalby gun director used a pair of trackers and mechanical tachymetry; the operator entered the fuse length, and deflection angles were read from the instruments.

Question: Deflection settings were also called what?
Ans:
aim-off