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Photosynthesis Review. Photosynthesis 1. Define photosynthesis. Photosynthesis is the process by which photosynthetic organisms convert solar energy into.

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Presentation on theme: "Photosynthesis Review. Photosynthesis 1. Define photosynthesis. Photosynthesis is the process by which photosynthetic organisms convert solar energy into."— Presentation transcript:

1 Photosynthesis Review

2 Photosynthesis 1. Define photosynthesis. Photosynthesis is the process by which photosynthetic organisms convert solar energy into chemical energy stored in sugars. 2. Name several photosynthetic organisms. Trees Algae Cyanobacteria

3 Photosynthesis 3. Using chemical formulas, write the balanced equation for photosynthesis. equation for photosynthesis. 4. Now write out the equation using words. Carbon dioxide + water yields sugar + oxygen 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Sunlight

4 Photosynthesis 5. What organelle in plants is involved in photosynthesis? photosynthesis? The chloroplast 6. What gives it the green color? The pigment chlorophyll

5 Photosynthesis 7. Where in plants are chloroplasts found? In the cells of soft plant tissue, like the green stems and leaves of celery. Note: Chloroplasts are also found in other colors of soft plant tissue, like the red leaves of a burning bush for example. They use secondary pigments, like carotenoids (orange color) and xanthophylls (yellow color) that are more predominant than green chlorophyll.

6 Photosynthesis 8. Identify the chloroplasts in this micrograph of elodea cells. elodea cells. Chloroplasts Elodea plant Elodea plant cells

7 Photosynthesis Identify the following structures of the chloroplast. 9

8 Photosynthesis Identify the following structures of the chloroplast. Outer membrane

9 Photosynthesis Identify the following structures of the chloroplast. 10

10 Photosynthesis Identify the following structures of the chloroplast. Inner membrane

11 Photosynthesis Identify the following structures of the chloroplast. 11

12 Photosynthesis Identify the following structures of the chloroplast. Inner membrane space

13 Photosynthesis Identify the following structures of the chloroplast. 12

14 Photosynthesis Identify the following structures of the chloroplast. Stroma

15 Photosynthesis Identify the following structures of the chloroplast. 13

16 Photosynthesis Identify the following structures of the chloroplast. Thylakoids

17 Photosynthesis Identify the following structures of the chloroplast. 14

18 Photosynthesis Identify the following structures of the chloroplast. Thylakoid space (lumen)

19 Photosynthesis Identify the following structures of the chloroplast. 15

20 Photosynthesis Identify the following structures of the chloroplast. Granum A stack of thylakoids

21 Photosynthesis 16. Photosynthesis occurs in two parts. One is the light-dependent reaction. What is the the light-dependent reaction. What is the other part called? other part called? The other is the light-independent reaction. 17. Which of these two reactions can occur during both the daytime and nighttime? both the daytime and nighttime? The light-independent reaction (it doesn’t require light).

22 Photosynthesis 18. Where in the chloroplast do the light-dependent reactions occur? reactions occur? The light-dependent reactions occur in the thylakoids

23 Photosynthesis 19. Where in the chloroplast do the light- independent reactions occur? independent reactions occur? The light-independent reactions occur in the stroma.

24 Photosynthesis 20. Sometimes the light-independent reaction is called the “dark” reaction. Why is dark reaction called the “dark” reaction. Why is dark reaction not an appropriate term to use? not an appropriate term to use? The use of the word dark makes one think that the reaction only occurs in the dark. This is not true since the reactions can take place in the light too—it is just light is not required for the reaction to occur.

25 Photosynthesis 21. What is another name for the light-independent reactions that occur in the stroma? reactions that occur in the stroma? The light-independent reaction is also called the Calvin Cycle, in honor of Melvin Calvin, who worked out the metabolic pathway of photosynthesis. Chloroplast Also known as the light-independent reaction.

26 Photosynthesis The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions. Chloroplast

27 Photosynthesis Chloroplast Light energy 23 The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions

28 Photosynthesis Chloroplast Light energy The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions H2OH2OH2OH2O Water

29 Photosynthesis Chloroplast Light energy The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions H2OH2OH2OH2O O2O2O2O2 Water Oxygen

30 Photosynthesis Chloroplast Light energy The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions. 26 ATP 27 H2OH2OH2OH2O O2O2O2O2 Water Oxygen

31 Photosynthesis Chloroplast Light energy H2OH2OH2OH2O The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions. O2O2O2O2 CO 2 ATP 27 Water Oxygen Carbon dioxide

32 Photosynthesis Chloroplast Light energy H2OH2OH2OH2O The bean-shaped object below represents a chloroplast. The green disks are thylakoids and the tan area is the stroma. Identify the outputs and inputs of the light- dependent and light-independent (Calvin cycle) reactions. O2O2O2O2 CO 2 ATP C 6 H 12 O 6 Water Oxygen Carbon dioxide Sugar (glucose)

33 Photosynthesis The sugars are used to help the plant live, grow, and reproduce. Some sugars are used to make other compounds, and some end up at the mitochondria to be converted into ATP, which is then used to drive cellular reactions. 28. What do plants do with the sugars they make from photosynthesis? from photosynthesis? Everything above can be made from sugars

34 Photosynthesis The excess sugars are stored as starch. 29. What do plants do with the excess sugars they make during photosynthesis? make during photosynthesis? Starch grains (stained purple) in plant cells.

35 Photosynthesis Since it will not be able to make glucose through photosynthesis, the plant must access glucose from starch reserves. The plant will most likely deplete its starch supply in that time. Thus the plant will be destarched. 30. What will happen if a plant is placed in the dark for 48 hours? for 48 hours?

36 Photosynthesis a. Destarch a plant by leaving it in the dark for 48 hrs. b. Next, cover a section of one leaf with cardboard. An Experiment in photosynthesis c. Finally, expose the leaf to light for 24 hours

37 Photosynthesis d. Remove cardboard and pick off the leaf. e. Put the leaf in hot water for a few minutes. An Experiment in photosynthesis (continued)

38 Photosynthesis An Experiment in photosynthesis (continued) f. Remove the leaf. g. Test for starch using iodine solution. Iodine Solution

39 Photosynthesis An Experiment in photosynthesis (continued) 31. What do you think will happen? Iodine Solution

40 Photosynthesis An Experiment in photosynthesis (continued) 31. What do you think will happen? The leaf cells under the cardboard would not receive any light and thus would not make sugars or store any starch. The areas exposed to light would store starch and test positive with iodine, turning a black color. No light, no starch Exposure to light Positive for starch

41 Photosynthesis 32. As previously mentioned, chlorophyll is green. Why is chlorophyll green and not some other color? is chlorophyll green and not some other color? White light is made up of many colors. Chlorophyll absorbs all of these colors except green, which is reflected back into our eyes.

42 Photosynthesis 33. Study the chart below. What color(s) of light does chlorophyll absorb best? chlorophyll absorb best? Chlorophyll absorbs red and blue light energies the best.

43 Photosynthesis 34. What would happen to the health of a plant that was grown under red and blue filters? was grown under red and blue filters? The plant will do poorly since the red and blue light energies chlorophyll absorbs best are being reflected away by the filters.


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