填空题. Some people say love makes the world go around. Others say it is not love; it's money. Since the truth is that it is energy that makes the world go 1 around. Energy is the currency of the ecological system and life becomes possible even when food is converted into energy, which in turn is used to 2 seek more food to grow, to reproduce and to survive. In this cycle all life 3 depends. It is fairly well-known that wild animals survive from year to year by eating as many as they can during times of plenty, the summer and fall, 4 storing the excess, usually in the form of fat, and then using these reserves of fat to survive during the hard time in winter when food is scarce. But it is 5 probably less well-known that even with their stored fat, wild animals spend less energy to live in winter than in summer. A good case in point is white-tailed 6 deer. Like most wildlife, deer reproduce, grow and store fat in the summer and fall when there is plenty of nutritious food available. A physically mature female deer in the good condition who has conceived in 7 November and was given birth to two fawns during the end of May and first 8 part of June, must search for food for the necessary energy not only to meet her body's needs but also to reproduce milk for her fawns. The best milk 9 production occurs at the same time that new plant growth is available. This is good timing, because milk production is an energy consuming process—it requires a lot of food. The cost can be met unless the region has ample food 10 resources.