A Fable for tomorrow Liu Dan
A Fable for Tomorrow Liu Dan Unit 15
Background Information ♂ Know what?
Background Information ♂ Know what ?
Man and Environment Introduction t-Ecosystem -i Deforestation 于 Pollution
Man and Environment Introduction Ecosystem Deforestation Pollution
Introduction Although the world is large, man is able to live in only a small part of it. The atmosphere is only about eleven kilometers thick. The soil that supplies us with food is only about fifteen centimeters thick and man can live on only about one eighth of the worlds surface. In the past two hundred years man has greatly changed his environment. Water has been given to deserts. Roads have been built across deserts and through forests Cities have grown to an astonishing size. many scientists think that man may not find life pleasant in the world of the future
Introduction Although the world is large, man is able to live in only a small part of it. The atmosphere is only about eleven kilometers thick. The soil that supplies us with food is only about fifteen centimeters thick and man can live on only about one eighth of the world’s surface. In the past two hundred years man has greatly changed his environment. Water has been given to deserts. Roads have been built across deserts and through forests. Cities have grown to an astonishing size. Many scientists think that man may not find life pleasant in the world of the future
Ecosystem any closed world in which life exists Oxygen Cycle Nitrogen Cycle This is the cycle that keeps A large part of the air consists of nitrogen gas, which joins with up our oxygen supply other substances to form nitrates When we breathe in we The nitrates are taken in by plants use up the oxygen in the Animals then eat these plants air. Carbon dioxide is Their wastes return some of the produced and is breathed nitrogen compounds to the soil out. Trees and plants Later bacteria break down these breathe in the carbon compounds. Simple nitrogen compounds are formed as well as dioxide we produce. They free nitrogen gas. The simple then give out oxygen. So compounds are used up by plants the cycle repeats again. The gas returns to the atmosphere
Ecosystem: any closed world in which life exists Oxygen Cycle This is the cycle that keeps up our oxygen supply. When we breathe in we use up the oxygen in the air. Carbon dioxide is produced and is breathed out. Trees and plants breathe in the carbon dioxide we produce. They then give out oxygen. So the cycle repeats. Nitrogen Cycle A large part of the air consists of nitrogen gas, which joins with other substances to form nitrates. The nitrates are taken in by plants. Animals then eat these plants. Their wastes return some of the nitrogen compounds to the soil. Later bacteria break down these compounds. Simple nitrogen compounds are formed as well as free nitrogen gas. The simple compounds are used up by plants again. The gas returns to the atmosphere