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| | Valdai Hills -- Encyclopædia Britannica |
 | | It occupies an area of 32,471 square miles (84,100 square km) and extends from the morainic Valdai Hills in the southwest, across the broad, swampy plain of the upper Volga River, to the shore of the huge Rybinsk Reservoir in the northeast. |
 | | The river basin drains some 533,000 square miles (1,380,000 square kilometres), stretching from the Valdai Hills and Central Russian Upland in the west to the Ural Mountains in the east and narrowing sharply at Saratov in the south. |
 | | Hill, who was born on April 2, 1899, discovered in 1937 that isolated chloroplasts (the green particles responsible for photosynthesis in plants) could produce oxygen from water in the presence of light and an appropriate chemical compound introduced to serve as an electron acceptor, a process that became known as the Hill reaction. |
| www.britannica.com /eb/article-9074664 (717 words) |
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