Chapter 6: Where it starts – Photosynthesis



Chapter 6: Where it starts – Photosynthesis

Exploring the Rainbow

Match each of the following terms with the correct definition.

1. carotenoids

2. absorption spectrum

3. chemoautotroph

4. chlorophyll a

5. photoautotroph

6. pigment

7. wavelength

a. extract energy and carbon from inorganic material in the environment

b. a unit that is used to identify light

c. the main photosynthetic pigment of plants

d. use light energy to build organic molecules from inorganic materials

e. first discovered by Engelmann, this is used to identify the wavelengths of light absorbed by a pigment

f. an accessory pigment that extends the range of photosynthesis

g. an organic compound that selectively absorbs light of specific wavelengths

8. In an absorption spectrum, such as the one shown in Figure 6.4, what do the peaks represent?

Light-Dependent Reactions

Provide the missing term for each numbered item in the diagram below.

1.

2.

3.

4.

5.

6.

7.

If the statement is true, place a T in the blank. If the statement is false, correct the underlined word to make the statement correct.

8. The chloroplast is the plant organelle that specializes in photosynthesis.

9. During the light-independent reactions, light energy is converted to chemical energy.

10. The light-harvesting pigments of photosynthesis are found in the stroma of a chloroplast.

11. The sugars of photosynthesis are manufactured in the thylakoids.

12. Glucose synthesis occurs in the light-independent reactions of photosynthesis.

Provide the missing term for each numbered item in the diagram below.

[pic]

13.

14.

15.

16.

17.

18.

19.

20.

Light-Independent Reactions: The Sugar Factory

Choose the appropriate form of electron flow for each of the following statements.

a. cyclic b. non cyclic c. both cyclic and noncyclic

1. forms ATP

2. forms NADPH

3. lost electrons are replaced by photolysis

4. electrons proceed through an electron transfer chain

5. is used when NADPH supplies are plentiful in the cell

6. oxygen is released as a byproduct

7. the first to evolve in photosynthetic organisms

Identify each numbered part of the diagram, using abbreviations where appropriate. Complete the exercise by entering the letter of the correct statement in the parentheses following each label.

8. ( )

9. ( )

10. ( )

11. ( )

12. ( )

13. ( )

14. ( )

a. Donates hydrogens and electrons to PGA molecules

b. Gets phosphate groups from ATP, priming them for synthesis reactions that generate RuBP

c. Rubisco attaches the carbon atom of CO2 to RuBP, which starts the Calvin-Benson cycle; this compound forms from splitting of an intermediate compound.

d. Gets a phosphate group from ATP, plus hydrogen and electrons

e. In the air spaces inside a leaf; diffuses into photosynthetic cells

f. Formed by a combination of two of twelve PGAL molecules

g. Donates phosphate groups to PGA

A Burning Concern

For each of the following, choose the most appropriate form of adaptation from the list below.

a. C3 plants b. C4 plants c. CAM plants

1. Succulents such as cacti, which have juicy, water-storing tissues, and thick surface layers.

2. The three-carbon PGA, the first stable intermediate of the Calvin-Benson cycle.

3. Four-carbon oxaloacetate is the first to form.

4. They open their stomata and fix carbon at night.

5. Two types of photosynthetic cells occur in these plants.

6. Evolved independently over millions of years in many lineages

7. With CO2 levels rising, these plants may again have the edge.

8. Do not grow well in hot, dry climates without steady irrigation.

9. These plants survive prolonged droughts by closing stomata even at night.

10. In the first cell type, the carbon-fixing enzyme ignores O2, no matter how much there is; CO2 is deposited in bundle sheath cells.

11. CO2 is fixed by repeated turns of a type of C4 cycle, then it enters the Calvin-Benson cycle the next day.

12. An example is the basswood tree

13. These plants lose less water and make more sugar than the C3 plants can when days are dry

14. When oxygen level is high, rubisco uses oxygen instead of CO2 in an alternate reaction that yields only one molecule of PGA

15. Common in grasses, corn, and other plants that evolved in the tropics.

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