Photosynthesis Review

Photosynthesis Review

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

3. Using chemical formulas, write the balanced equation for photosynthesis. Photosynthesis Sunlight 6CO2 + 6H2O C6H12O6 + 6O2 4. Now write out the equation using words. Carbon dioxide + water yields sugar + oxygen

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

7. Where in plants are chloroplasts found? In the cells of soft plant tissue, like the green stems and leaves of celery . Photosynthesis 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.

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

Identify the following structures of the chloroplast. Photosynthesis 9

Identify the following structures of the chloroplast. Outer membrane Photosynthesis

Identify the following structures of the chloroplast. Inner membrane Photosynthesis

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

Identify the following structures of the chloroplast. 12 Photosynthesis

Identify the following structures of the chloroplast. Stroma Photosynthesis

Identify the following structures of the chloroplast. Thylakoids Photosynthesis

Identify the following structures of the chloroplast. 14 Photosynthesis

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

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

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

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

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

20. Sometimes the light-independent reaction is called the “dark” reaction. Why is dark reaction not an appropriate term to use? Photosynthesis 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.

21. What is another name for the light-independent reactions that occur in the stroma? Photosynthesis 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.

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. Photosynthesis 25 23 26 22 Chloroplast 24 27

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. Photosynthesis 25 23 26 Light energy Chloroplast 24 27

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. Photosynthesis H2O 25 Water 26 Light energy Chloroplast 24 27

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. Photosynthesis H2O 25 Water 26 Light energy Chloroplast 27 O2 Oxygen

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. Photosynthesis ATP H2O Water 26 Light energy Chloroplast 27 O2 Oxygen

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. Photosynthesis ATP H2O CO2 Water Carbon dioxide Light energy Chloroplast 27 O2 Oxygen

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. Photosynthesis ATP H2O CO2 Water Carbon dioxide Light energy Chloroplast O2 C6H12O6 Oxygen Sugar (glucose)

28. What do plants do with the sugars they make from photosynthesis? 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. Everything above can be made from sugars

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

30. What will happen if a plant is placed in the dark for 48 hours? 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.

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

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

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

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

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

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

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

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

Photosynthesis Review