1. Bioenergetics Food Chain BCH 341 lecture 2

2. Food and energy in an ecosystem All living organisms need energy. All living organisms need energy. All the energy comes from the sun. All the energy comes from the sun. some of the energy in sunlight captured by plants (phototrophic). some of the energy in sunlight captured by plants (phototrophic). Every food chain start with green plants. Every food chain start with green plants. food chains are usually short. food chains are usually short. Consumers feeds at different trophic levels. Consumers feeds at different trophic levels. Decomposers release minerals from dead organisms. Decomposers release minerals from dead organisms. BCH 341 lecture 2

3. Food Chain Oxygen, Carbon dioxide, nitrogen and water are cycling continuously between the animal and plant worlds. BCH 341 lecture 2

4. Food Webs BCH 341 lecture 2

5. Oxygen, Carbon dioxide and Nitrogen cycles The food chain thus return simple forms of carbon to the soil and atmosphere. The food chain thus return simple forms of carbon to the soil and atmosphere. Oxygen, Carbon dioxide, nitrogen and water are cycling continuously between the animal and plant worlds. Oxygen, Carbon dioxide, nitrogen and water are cycling continuously between the animal and plant worlds. BCH 341 lecture 2

6. Oxygen Cycle Almost all living things need oxygen. They use this oxygen during the process of creating energy in living cells. Almost all living things need oxygen. They use this oxygen during the process of creating energy in living cells. Just as water moves from the sky to the earth and back in the hydrologic cycle, oxygen is also cycled through the environment. Just as water moves from the sky to the earth and back in the hydrologic cycle, oxygen is also cycled through the environment. Plants mark the beginning of the oxygen cycle. Plants mark the beginning of the oxygen cycle. BCH 341 lecture 2

7. Plants are able to use the energy of sunlight to convert carbon dioxide and water into carbohydrates and oxygen in a process called photosynthesis. Plants are able to use the energy of sunlight to convert carbon dioxide and water into carbohydrates and oxygen in a process called photosynthesis. 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 This means that plants "breathe" in carbon dioxide and "breathe" out oxygen. This means that plants "breathe" in carbon dioxide and "breathe" out oxygen. SUN lightenergy (glucose) BCH 341 lecture 2

8. Animals form the other half of the oxygen cycle. We breathe in oxygen which we use to break carbohydrates down into energy in a process called respiration (Previously demonstrated). Animals form the other half of the oxygen cycle. We breathe in oxygen which we use to break carbohydrates down into energy in a process called respiration (Previously demonstrated). C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + Carbon dioxide produced during respiration is breathed out by animals into the air. Carbon dioxide produced during respiration is breathed out by animals into the air. BCH 341 lecture 2 ATP glucose glucose energy

9. Carbon Cycle Carbon Cycle Essential part of CHO, Fat & proteins. Air contain about 0.03% CO 2. BCH 341 lecture 2

10. Nitrogen essential to make proteins. The air is about 79% nitrogen gas. N 2 is very inert which mean that they will not react with other substances. So, the animals and plants cannot use it at all. nitrogen fixation It must be changed into a more reactive form such as NH 3 or NO 3- (nitrogen fixation). Nitrogen Cycle Nitrogen Cycle BCH 341 lecture 2

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12. Nitrogen fixation Nitrifying bacteria Nitrifying bacteria Denitrifying bacteria Denitrifying bacteria Because of the nitrogen cycle, the percentage of nitrogen remains constant in the air. Because of the nitrogen cycle, the percentage of nitrogen remains constant in the air. BCH 341 lecture 2

13. Micro-organisms involved in Nitrogen Cycle BCH 341 lecture 2