Mastering Biology: Photosynthesis Flashcards

Questions and Answers

How is photosynthesis similar in C4 plants and CAM plants?

In both cases, thylakoids are not involved in photosynthesis.

Both types of plants make sugar without the Calvin cycle.

Both types of plants make most of their sugar in the dark.

In both cases, rubisco is not used to fix carbon initially. (correct)

In both cases, electron transport is not used.

Which of the following does NOT occur during the Calvin cycle?

Oxidation of NADPH

Regeneration of the CO2 acceptor

Release of oxygen (correct)

Consumption of ATP

Carbon fixation

Which process is most directly driven by light energy?

Reduction of NADP+ molecules

Carbon fixation in the stroma

ATP synthesis

Creation of a pH gradient by pumping protons across the thylakoid membrane

Removal of electrons from chlorophyll molecules (correct)

If you ran the same experiment without passing light through a prism, what would you predict?

The bacteria would be relatively evenly distributed along the algal filaments. Signup and view all the answers

In autotrophic bacteria, where is chlorophyll located?

In the infolded plasma membrane Signup and view all the answers

If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later analysis will show that all of the following molecules produced by the algae contain 18O except

O2 Signup and view all the answers

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

Photophosphorylation Signup and view all the answers

Which of the following conclusions can be drawn from the experimental conditions involving chloroplast membrane vesicles equilibrated in a solution of pH 5, then adjusted to pH 8?

ATP will not be produced because there is no ADP and inorganic phosphate in the solution. Signup and view all the answers

When light strikes chlorophyll molecules of PS II, they lose electrons, which are ultimately replaced by _____.

Electrons released by splitting water Signup and view all the answers

What does the chemiosmotic process in chloroplasts involve?

Establishment of a proton gradient across the thylakoid membrane Signup and view all the answers

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?

The isolated chloroplasts will make ATP. Signup and view all the answers

Which of the following statements best describes the relationship between photosynthesis and respiration?

Photosynthesis stores energy in complex organic molecules, whereas respiration releases it. Signup and view all the answers

The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during

Neither photosynthesis nor respiration. Signup and view all the answers

In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic 'knobs' of ATP synthase would be located

On the stromal side of the membrane. Signup and view all the answers

The reactions that produce molecular oxygen (O2) take place in

The light reactions alone. Signup and view all the answers

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP Signup and view all the answers

After 3-PGA is phosphorylated, it is reduced by _____.

NADPH Signup and view all the answers

In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.

Cytoplasm Signup and view all the answers

C4 plants differ from C3 and CAM plants in that C4 plants _____.

Transfer fixed carbon dioxide to cells in which the Calvin cycle occurs Signup and view all the answers

C4 plants occur more commonly in desert conditions because _____.

They can fix carbon at the lower CO2 concentrations that develop when the stomata are closed Signup and view all the answers

What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?

C3 plants will have faster growth; C4 plants will be minimally affected. Signup and view all the answers

Reactions that require CO2 take place in

The Calvin cycle alone. Signup and view all the answers

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

Fix CO2 into organic acids during the night. Signup and view all the answers

Study Notes

Photosynthesis Overview

Photosynthesis produces glucose and oxygen from carbon dioxide and water, utilizing light energy.
Two main stages: light-dependent reactions and the Calvin cycle (light-independent reactions).

C4 and CAM Plants

C4 plants and CAM plants both initially fix carbon without using rubisco.
C4 plants transfer fixed carbon dioxide to cells where the Calvin cycle occurs, while CAM plants fix CO2 at night and store it as organic acids.

Calvin Cycle

Does not release oxygen; it involves carbon fixation, ATP consumption, and regeneration of RuBP.
Carbon dioxide is added to RuBP (ribulose bisphosphate) during this cycle.

Light-Driven Processes

Light energy directly drives the removal of electrons from chlorophyll molecules.
Photophosphorylation refers to ATP production via light energy capturing in chlorophyll.

Chemiosmotic Process

Establishment of a proton gradient across thylakoid membranes is crucial for ATP production.
Protons flow from the thylakoid space through ATP synthase to generate ATP.

Light Reactions

Molecular oxygen (O2) is produced exclusively during the light reactions.
Electrons replenished in PS II come from the splitting of water.

Chlorophyll in Bacteria

In autotrophic bacteria, chlorophyll is located in the infolded plasma membrane.

Impact of pH Change

Adjusting solution pH from 5 to 8 creates a proton gradient, allowing ATP synthesis, but requires ADP and inorganic phosphate.

Photosynthesis vs. Respiration

Photosynthesis stores energy in organic molecules; respiration releases that energy.
Respiration operates the biochemical pathways of photosynthesis in reverse.

Carbon Fixation and Sugar Production

After phosphorylation, 3-PGA is reduced by NADPH to form G3P (glyceraldehyde 3-phosphate).
Glucose is produced through multiple G3P molecules during the final stages of the Calvin cycle.

Effects of CO2 Concentration

Doubling atmospheric CO2 will likely increase growth rates in C3 plants while minimally affecting C4 plants, which are adapted to lower CO2 conditions.

Experimental Predictions

In Engelmann's experiment, bacteria would be evenly distributed along algal filaments without wavelength differentiation.
Acidic thylakoid conditions followed by a switch to pH 8 will lead to ATP production in isolated chloroplasts.

Stomata Functionality

CAM plants close stomata during the day to conserve water and fix CO2 at night.
C4 plants are adapted to fix carbon efficiently during the day even with closed stomata.

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Description

Test your understanding of photosynthesis with this set of flashcards focusing on the similarities between C4 and CAM plants. Explore the roles of rubisco and the Calvin cycle in these plant processes. This quiz is perfect for biology students looking to reinforce their knowledge.