ID：9406-6838 Most animals use more than one species as food. Therefore, the term “food web” is a better description of food relationships than “food chain”. A food web is a complex feeding system that contains several food chains. For example, mice, rabbits, and deer eat plants. owls eat mice and rabbits. Mountain lions eat rabbits and deer. These five species are parts of food chains that together form a food web. The first link in a food chain is always a green plant. Only organisms with chlorophyll, such as green plants can make food. for example, the first link aquatic food chains is algae. Most algae are microscopic green plants that produce food by photosynthesis. In photosynthesis, energy from sunlight converts carbon dioxide and water to sugar. Tiny fish in lakes, streams and oceans eat algae. In turn, these tiny fish are eaten by larger fish. The larger fish are eaten by still larger fish. The food supply for fish is made by algae. This food is then passed through the food chains as one animal eats another. Organisms may be divided into three groups based on how they obtain food. These groups are producers, decomposer and consumer. Organisms containing chlorophyll are producers. thus, green plants are producers. Animals that eat other animals and plants as consumers. Microbes, one-celled organisms that cause the decay of dead plants and animals are decomposers. Since decomposers cannot make their own food, they are also consumers. 1. The main purpose of the passage is to. A. determine which food chain is the most efficient B. describe the food network among plants and animals C. explain the process of photosynthesis in green plants D. appeal to conservationists to protect endangered plant species 2. According to the author, what is a “food web”? A. A complicated system of several food chains B. A society that distributes food C. The relationship of one green plants to another D. The device that spiders use to catch food 3. Which of the following would most likely be the first link in a food chain? A. Termites B. Fish C. Lions D. Grass 4. The author divides organisms according to. A. how they use up energy B. how they obtain food C. how much energy they require in order to move D. whether they live on the land or in the sea 5. Which of the following organism could not be a consumer as described in the passage? A. a microbe B. a rabbit C. a tree D. a fish
（翻译）Previously, enzymes were prepared mainly from animal organs and plant seeds. However, these sources of enzyme have their limits both in quantity and quality. Microbes, on the contrary, can be cultured at large scale by simple methods. Also, in this case, selective production of certain enzyme in large quantities is possible by adjusting the conditions of culture. Further, microbes have marked adaptability, and mutant species can be induced artificially. Thanks to these advantageous properties, enzymes which cannot be produced from animals and plants can be obtained from microbes.
