Bio 111- Chapter 7 Photosynthesis Essay

A product of photosynthesis, ______, is the chief source of energy for most organisms. a. oxygenb.

sucrosec. glucose d. all of the above

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c. glucose
During the light reactions what structure is responsible for absorbing the solar energy? a. chloroplastb. stromac. stomad. bark of the tree


Photorespiration occurs mainly in: a. C3 plantsb. C4 plantsc. CAM plantsd.

all of the above

a. C3 plants
The function of sunlight in photosynthesis is to:a. reduce NADPH to NADPb. fix O2 in the Calvin cyclec. excite electrons in chlorophyll d. combine carbon dioxide and water to form ATP and NADPH

excite electrons in chlorophyll

To what does the term grana refer?a. the double membrane of the chloroplastb. a flattened disk or sac in the chloroplastc. a stack of thylakoid membrane structuresd. the central fluid-filled space of the chloroplast e. the cytochrome system in the membranes of the thylakoids
c. a stack of thylakoid membrane structures
Which of these is NOT a major photosynthetic pigment in plants?a.

chlorophyll ab. chlorophyll bc. chlorophyll cd. carotenoid pigments

c. chlorophyll c
The major enzyme that fixes carbon dioxide is calleda. ribulose bisphosphate carboxylase (rubisco)b. glyceraldehyde-3-phosphate (G3P)c.

PEP carboxylase (PEPcase) d. lactate dehydrogenase

a. ribulose bisphosphate carboxylase (rubisco)
What organisms are capable of photosynthesis?a.

plants onlyb. plants and algae onlyc. plants and some bacteria onlyd.

plants, algae, and some bacteria

d. plants, algae, and some bacteria
Which is most closely associated with the Calvin cycle? a. ATP production b. oxygen productionc. carbon dioxide fixationd.

carbon dioxide productione. removal of electrons from water for passage through an electron transport system

c. carbon dioxide fixation
1. The absorption spectrum of chlorophylla. is not the same as that of carotenoids.b. approximates the action spectrum of photosynthesis.

c. explains why chlorophyll is a green pigment.d. shows that some colors of light are absorbed more than others. e. all of the above

e. all of the above
2. The final acceptor of electrons during the noncyclic electron pathway isa.

PS I b. PS II b. ATP d. NADP+e. water

d. NADP+

T/F RuBP carboxylase is the enzyme that fixes carbon dioxide to RuBP in the Calvin cycle.

10. T/F When 3PG becomes G3P during the light reactions, carbon dioxide is reduced to carbohydrate.
11. T/F NADPH and ATP cycle between the Calvin cycle and the light reactions constantly.
12. The NADPH and ATP from the light ractios are used to a. split waterb.

cause RuBP carboxylase to fix CO2. c. re-form the photosystems d. cause electrons to move along their pathways e. convert 3PG to G3P

e. convert 3PG to G3P

Chemiosmosis a. depends on complexes in the thylakoid membraneb. depends on an electrochemical gradient. c. depends on a difference in H+ concentration between the thylakoid space and the stromad. results in ATP formation e. all of the above

e. all of the above

The function of the light reactions is to a. obtain CO2b. make carbohydratec. convert light energy into a usable form of chemical energyd.

regenerate RuBP

c. convert light energy into a usable form of chemical energy
16. The oxygen given off by photosynthesis comes from a. H2Ob. CO2c.

glucosed. RuBP

a. H2O
17. The glucose formed by photosynthesis can be used by plants to make a. starch b. cellulosec.

lipids and oilsd. proteinse. all of the above

e. all of the above
18. The Calvin cycle reactions a. produce carbohydrateb.

convert one form of chemical energy into a different form of chemical energyc. regenerate more RuBPd. use the products of the light reactionse. all of the above


all of the above

19. CAM photosynthesis a. is the same as C4 photosynthesisb.

is an adaption to cold environments in the southern hemispherec. is prevalent in desert plants that close their stomata during the dayd. occurs in plants that live in marshy arease. stands for chloroplasts and mitochondria

c. is prevalent in desert plants that close their stomata during the day
20. C4 photosynthesisa. is the same as C3 photosynthesis because it takes place in chloroplasts.

b. occurs in plants whose bundle sheath cells contain chloroplastsc. takes place in plants such as wheat, rice, and oats.d. is an advantage when the weather is hot and drye. both b and d are correct

d. is an advantage when the weather is hot and dry
Produce their own food.

Takes place in the green portions of plants. The raw materials for photosynthesis are carbon dioxide and water. A process that captures solar energy, transforms solar energy into chemical energy , energy ends up stored in a carbohydrate. Photosynthesizers produce food energy and feed themselves as well as heterotrophs.
Ingest food.
Specialized to carry out photosynthesis.
Carbon dioxide enters a leaf through small openings called stomata and diffuses into chloroplasts in mesophyll cellsIn stroma, CO2 is combined with H2O to form C6H12O6 (sugar).

Absorb solar energy and energize electrons prior to reduction of CO2 to a carbohydrate.
Light Reactions
Take place only in the presence of light. Energy?capturing reactions, chlorophyll absorbs solar energy, this energizes electrons, electrons move down an electron transport chain.
Calvin Cycle Reactions
Take place in the stroma. CO2 is reduced to a carbohydrate, use ATP and NADPH to produce carbohydrate.
Chemicals that absorb certain wavelengths of light.

Wavelengths that are not absorbed are reflected/transmitted.

Noncyclic Pathway
Takes place in the thylakoid membrane.Uses two photosystems, PS I and PS II.PS II captures light energy, PS I captures light energy and ejects an electron.
Consists of a pigment complex and electron acceptors, receives electrons from the splitting of water, oxygen is released as a gas.
Electron Transport Chain
Consists of cytochrome complexes and plastoquinone, carries electrons between PS II and PS I, also pumps H+ from the stroma into the thylakoid space.

Has a pigment complex and electron acceptors, adjacent to the enzyme that reduces NADP+ to NADPH.
ATP Synthase Complex
Has a channel for H+ flow, H+ flow through the channel drives ATP synthase to join ADP and Pi.
Importance of the Calvin Cycle
G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules.

The hydrocarbon skeleton of G3P can form:fatty acids and glycerol to make plant oils, glucose phosphate (simple sugar), fructose (which with glucose = sucrose), starch and cellulose, amino acids.

In hot, dry climates
Stomata must close to avoid wilting, CO2 decreases and O2 increases, O2 starts combining with RuBP
Production of CO2
CAM(Crassulacean-Acid Metabolism) Photosynthesis
CAM plants partition carbon fixation by time. During the night: CAM plants fix CO2, Form C4 molecules, which are stored in large vacuolesDuring daylight: NADPH and ATP are available, Stomata are closed for water conservation, C4 molecules release CO2 to Calvin cycle.
C4 Plants most adapted to
High light intensitiesHigh temperaturesLimited rainfall
C3 plants better adapted to
Cold (below 25°C)High moisture
CAM plants are better adapted to
Extreme aridityCAM occurs in 23 families of flowering plantsAlso found among nonflowering plants

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