BI110 Chapter Notes - Chapter 31: Phosphoenolpyruvate Carboxylase, C3 Carbon Fixation, C4 Carbon Fixation

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mauveleopard62

23 Jan 2019

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Module 31 c3, c4, and cam photosynthesis. Most plants utilize the ancestral c3 photosynthetic pathway, plants that use c4 and. Cam photosynthesis photosynthesize more efficiently in hot and dry environments. C4 and cam photosynthetic pathways independently evolved many times among plants during periods of low atmospheric co2 levels. All plants use the enzyme rubisco in carbon fixation. In the case of c3 photosynthesis, the first stable organic product of carbon fixation is a 3-carbon compound, glycerate-3- phosphate. Rubisco catalyzes another reaction besides the fixation of co2. O2 and co2 compete for rubisco"s active site, although the enzyme intrinsically favours co2 over o2. Because o2 levels are several hundred-fold higher than co2 in today"s atmosphere, the oxygenase side-reaction can reduce a plant"s photosynthetic efficiency by as much as 50% When rubisco catalyzes the reaction with oxygen, it uses energy; atp is consumed without producing carbohydrates called photorespiration. For photorespiration, the energy-generating reactions take place in the mitochondria.

Related Questions

5: chloroplast kept in the dark can continue to make sugar is provided with

A: NADPH, CO2, and ADP

B: CO2, and ATP

C: NADPH, ATP, and CO2

D: NADPH and ATP

E: water and ATP

7: C3 plants are more susceptible to photorespiration than either C4 or CAM plants. Why do most plants lack the C4 pathway??

A: Switching between C3, C4, and CAM photosynthesis is very difficult for most plants

B: ?Rubisco is more efficient in C3 plants when compared to rubisco of C4 and CAM plants

C: Most plant species do not have vacuoles in their cells to store the malate generated from CO2 taken in during the night.

D; : Photorespiration is not a serious problem for most plants.?

E: There is an energetic cost to C4 and CAM pathways that only makes them advantageous in very hot and/or arid environments.?

8: In Engelmann's classic experiment, why were the oxygen-requiring bacteria clustered around the regions of Spirogyra algae that were bathed in red, blue, and violet light?

A; The bacteria were immobile and that is where Engelmann happened to place them

.?B; The most energy-rich wavelengths of light are found at the edges of visible and nonvisible light (ultra

violet and infrared)

C; Photosynthesis is most active in those wavelengths of light and thus more oxygen is consumed by the algae in those regions.

D: Photosynthesis is most active in those wavelengths of light and thus more oxygen is produced by the algae in those regions.?

E: : Chlorophyll is green and thus reflects green light.

9: In any experiment, changes to the dependent variable based on the manipulations of the independent variable are measured. When determining the action spectrum of a given plant, what is the independent variable and what is the dependent variable?

A: independent = rate of O2 release in photosynthesis; dependent = wavelength?

B: ?independent = absorption of light; dependent = wavelength

C: independent = wavelength; dependent = rate of O2 release in photosynthesis?

D: independent = wavelength; dependent = absorption of light?

E: independent = rate of O2 release in photosynthesis; dependent = absorption of light

11: In order to elucidate the Calvin cycle, Calvin and his colleagues used two-dimensional paper chromatography to analyze the presence of different molecules under different conditions. What did they conclude from the accumulation of RuBP when CO2 levels were low??

A: CO2 serves as a non-competitive inhibitor of rubisco.

B: RuBP is the last substrate to react in the Calvin cycle.

C: RuBP only reacts with CO2 when concentrations of ATP are low

D: RuBP is the first substrate to react with CO2

E: RuBP only reacts with CO2 in the sunlight

12: Why isn't oxygen produced by organisms that perform anoxygenic photosynthesis?

A; their membranes lack ATP synthase?

B; They use a different enzyme for the initial reactions of the calvin cycle

C: they use electrons donors other than water

D: their photosystem do not utilize the calvin cycle

E: their chorophyll contains an iron rather than magnesium

tanelk218

Review question its 1-12 sorry for the xtra questions in the bottom

1:2D chromatography is so named because ____

A: there are two steps: labeling with a radioactive marker and separation via chromatography

B: two different solutions are used in the paper chromatography

C: the molecules are separated into a linear arrangement, meaning two dimension

D: two different types of radioactive markers must be used

E: the process separates the molecules in two direction, first along the X and then along the Y axis

2: :Which molecule(s) regulate(s) photosynthesis by sensing the metabolic status of the chloroplast and regulating proton flow out of the thylakoid lumen??

A: ATP synthase

B: antenna complex

C: Chrolophyll B

D: carotenoids

E: chlorphyll A

3: When does A CAM plant take in atmospheric CO2?

A: daytime only

B: Summer day

C: winter day

D: nighttime only

E: anytime the calvin cycle is happening

4: Where can you find ATP synthase in a plant cell ?
A; in the thylakoid membrane only

B: in the mitochondial inner membrane

C: both thylakid and inner mitochondria membrane

D: only in the nucleus

E: embedded in the plasma membrane

5: chloroplast kept in the daek can continue to make sugar is provided with