THE PROCESS OF SCIENCE 10. Tropical rain forests cover only about 3% of Earth\'s
ID: 301410 • Letter: T
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THE PROCESS OF SCIENCE 10. Tropical rain forests cover only about 3% of Earth's surface, but they are estimated to be responsible for more than 20% of global photosynthe- sis. For this reason, rain forests are often referred to as the "lungs" of the planet, providing O2 for life all over Earth. However, most experts believe that rain forests make little or no net contribution to global O2 produc- tion. From your knowledge of photosynthesis and cellular respiration, can you explain why they might think this? (Hint: What happens to the en- ergy stored as sugars in the body of a plant when that plant dies or parts of it are eaten by animals?) 11. Suppose you wanted to discover whether the oxygen atoms in the glu- cose produced by photosynthesis come from H20 or CO2. Explain how you could use a radioactive isotope to find out 12. Interpreting Data The graph above right is called an absorption spec- trum. Each line on the graph is made by shining light of varying wave- 14 lengths through a sample. For each wavelength, the amount of that light absorbed by the sample is recorded. This graph combines three such measurements, one each for the pigments chlorophyll a, chlorophyll b, and the carotenoids. Notice that the graphs for the chlorophyll pigments match the data presented in Figure 7.5. Imagine a plant that lacks chloro- phyll and relies only on carotenoids for photosynthesis. What colors of light would work best for this plant? How would this plant appear to your eye?Explanation / Answer
10). Tropical rain forest is ever green forest which are in northern sides.
Yes it is considered that they are lungs of earth but they have high respiration rate because they have high diversity as well as high growth and due to intense great at northern some of them are with high photorespiration. Here digestion of all stored sugar is to be done because those plants or tree have more height upto 200ft and more. So respiration is high. It means CO2 production is equivalent to O2 production. So Experts think that no net gain of O2 globally. Here, we can understand it through a fact which is like as:--
*Terrestrial plant produces O2 or contribute 51% but on the other hand aquatic environment accounts for 49% O2. Now no net contribution of rain forest means terrestrial contribute 51% means all contribution by rain forest and others also contribute but around 1% out of the 51%.
11). To know about O2 in C6H12O6 (glucose) that from where it comes.::--
1st case::-- Use a plant and supply it with H2O* here Oxgen has its redioactive isotope(O2*) and light CO2 and allowing it to go through photosynthesis and check through radioactive device where it is present in C6H12O6 and if you get then it means comes from water( H2O*) but practically it comes from CO2 not from water. In above case, O2* is released as gas means H2O contributes in O2 production.
2nd case ::--So this radiolabeled O2* now is incorporated in in carbon dioxide as CO2* so you will get O2 from CO2 not from H2O.
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