1. By: dania abida

2. Oxygen is a gas in the air. It is a product of photosynthesis. Photosynthesis is the plant’s food making process.four things are needed for photosynthesis to take place:

3. 1. sun light 2. Water 3. Cholorophyll 4. Carbon doixide(composes less than 1% of the air)

5. How does this process take place? Plants make their own food. During day light, green plants use special leaf cells(chloroplasts) that contain chlorophyll to trap sun light. Sun light energy is then used to combine water and carbon dioxide from the air to produce sugar and oxygen. Veins in the leaves are the small tubes that carry water to the leaf

7. Veins also transport food from the leaf to the stem and roots and carry the sugar the plant makes to all part of the plant. These sugars give the sweet taste to fruits such as grapes, apples, and pears.

9. this food making process is called photosynthesis. this food making process is called photosynthesis. Click here

10. The oxygen that the plant makes is released into the air. The plant stores the food that it makes until it is needed. When it is needed, the cell use oxygen to break apart sugar. When sugar break apart, they give off energy. This process is called respiration.

11. Respiration occurs day and night. The same process energy in animal cells.

12. In photosynthesis, plant use the energy from sun light to produce sugar and oxygen from carbon dioxide and water; then they release oxygen. Respiration uses oxygen and gives off carbon dioxide.

13. You can prepare a simple experiment to observe this for your self. Find an aquarium plant called elodea or any similar type of plant. Cut off a small portion of the stem. Place the plant with the cut stem in a jar or glass of water. The water level should be at

14. at least 1.25 cm above the cut stem. Place the jar out side or near a bright window or light. Wait a few minutes and watch the oxygen bubbles being released by the plant.

16. answer answer What happened? What process did the plant go through to give off oxygen?

17. Through the respiration process we receive the oxygen that is used in chemical reaction in our cells to give us energy and warmth, just as oxygen burns with gasoline to power our cars. We know that we need oxygen from the air, but do we need nithrogen?

18. Nitrogen, the main component of air (78%) is also a colorless, tasteless, and odorless gaseous chemical element. Nitrogen in the air dilutes the oxygen so things do not burn too quickly. It is one of three ingredients of proteins and DNA. it is an essential element in the

19. Structure of all living things. Although nitrogen makes up 78% of the Earth’s atmosphere, plants and animals cannot use it in this from. It is the nitrogen cycle, in which microscopic bacteria trans from nitrogen into a variety of components, that makes nitrogen useful to other living things.

20. Lightning and bacteria can convert nitrogen in the air directly into nitrates in the soil. Nitrates are soluble in water, and plants are able to absorb them through their roots. The nitrates act as a plant fertilizer. In turn, animals obtain their nitrogen from plants. the proteins

21. In waste material such as dung or dead plants and animal also contains nitrogen. Various bacteria break down the proteins and finally convert the nitrogen into nitrates that can be used by other organisms. Some of the nitrates are absorbed by plants and some complete the cycle when they are changed back to

22. Nitrogen gas by yet another kind of bacteria.

23. Nitrogen cycle Atmospheric nitrogen gas 78%