Photosynthesis Mechanisms Quiz

The process by which plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen.

The first stage of photosynthesis where light energy is captured and converted into chemical energy in the form of ATP and NADPH.

The second stage of photosynthesis where carbon dioxide is fixed into glucose using the energy from ATP and NADPH.

A green pigment that absorbs light energy and is essential for photosynthesis.

Two cooperating photosystems in the thylakoid membrane that work together to capture light energy.

The reaction center of photosystem I (PSI) that absorbs light energy at a wavelength of 700nm.

The process where oxygen is released as a byproduct of photosynthesis during the light-dependent reactions.

The conversion of light energy into chemical energy in the form of ATP and NADPH, primarily driven by the electron transport chain.

Photosystem II (PSII) is a complex of chlorophyll molecules found in the thylakoid membranes of chloroplasts. It plays a vital role in capturing light energy and converting it to chemical energy.

The reaction center of Photosystem II is called P680. This pigment molecule absorbs light at a peak wavelength of 680 nanometers.

Light harvesting complexes (LHC) are antenna-like structures within photosystems that capture light energy and funnel it into the reaction center.

Antenna molecules are protein-bound pigments that absorb photons of light and transfer their energy to the reaction center within a photosystem.

When a chlorophyll molecule absorbs a photon of light, an electron is excited to a higher energy level, momentarily transitioning the molecule to an excited state.

The excited state of chlorophyll is unstable and the electron quickly returns to its ground state, releasing the excess energy as heat.

The oxygen-evolving complex (OEC) is a component of Photosystem II responsible for splitting water molecules, releasing oxygen and generating protons.

The splitting of water molecules in PSII releases protons (H+) into the thylakoid lumen, contributing to the proton gradient that powers ATP synthesis.

Photophosphorylation is the process by which light energy is used to generate ATP, the energy currency of cells.

A proton motive force is generated across the thylakoid membrane, with a higher concentration of protons inside the lumen. This difference in concentration drives the production of ATP.

It describes the arrangement of mesophyll cells around the vascular bundles in C4 plants, where the bundle sheath cells surround the vascular bundles and mesophyll cells are located between the bundle sheath and the leaf surface.

This metabolic pathway allows certain plants to capture CO2 more efficiently in hot and dry environments. It involves an initial fixation of CO2 into a four-carbon compound, followed by its release in the bundle sheath cells, where it is used for the Calvin cycle.

A type of C4 photosynthesis where the release of CO2 occurs in the bundle sheath chloroplasts. Malate is converted to pyruvate, reducing NADP+..

A different type of C4 photosynthesis where the CO2 release occurs in the mitochondria of the bundle sheath cells. Malate is decarboxylated, reducing NAD+.

A mechanism for carbon fixation found in some plants, particularly succulents, where they open their stomata only at night, when it is cool and humidity is high, to minimize water loss.

Cyclic photophosphorylation uses Photosystem I only, cycling electrons back to the cytochrome complex via ferredoxin and plastocyanin. This generates ATP but doesn't produce NADPH or oxygen.

The Calvin cycle uses more ATP than NADPH. When NADPH accumulates, it triggers a shift from non-cyclic to cyclic electron flow to replenish ATP.

Non-cyclic photophosphorylation produces ATP, NADPH, and oxygen. These are essential for the Calvin cycle and other metabolic processes.

The Calvin cycle is the light-independent stage of photosynthesis where carbon dioxide is converted into glucose.

The Calvin cycle is a series of reactions that can be divided into three main phases: carbon fixation, reduction, and regeneration of RuBP.

In carbon fixation, carbon dioxide is incorporated into RuBP by the enzyme rubisco, forming unstable six-carbon compounds that split into two molecules of 3-phosphoglycerate.

In the reduction phase, each molecule of 3-phosphoglycerate receives a phosphate group from ATP, forming 1,3-bisphosphoglycerate. This is then reduced by NADPH to form glyceraldehyde 3-phosphate (G3P).

The regeneration phase uses five molecules of G3P to regenerate three molecules of RuBP, allowing the Calvin cycle to continue.

Glucose is a six-carbon sugar, C6H12O6, that is the primary product of photosynthesis. It's used as a source of energy and as a building block for other molecules.

Rubisco is the enzyme that catalyzes the first step in the Calvin cycle, the carbon fixation reaction. It's responsible for binding CO2 to RuBP.

C3 plants are the most common type of plant and they use the Calvin Cycle for photosynthesis. They function best in cool and wet climates but struggle in hot, dry conditions.

In C3 plants, stomata close to conserve water under stress, leading to a buildup of oxygen and a decrease in carbon dioxide. This hampers the Calvin cycle.

When stomata close, the buildup of oxygen in C3 plants causes Rubisco to use oxygen instead of carbon dioxide in the Calvin cycle. This is a less efficient process called photorespiration.

Photorespiration lowers photosynthetic output because it releases carbon dioxide, uses ATP, but doesn't produce sugar.

C4 plants have evolved a special mechanism for carbon fixation, resulting in the formation of a four-carbon compound.

In C4 plants, there are two types of photosynthetic cells: bundle sheath cells and mesophyll cells, each with specific roles in carbon fixation.

The Hatch-Slack pathway is the name given to the initial carbon fixation process in C4 plants. It results in the formation of a four-carbon compound.

C4 plants keep their stomata open for a shorter duration, minimizing water loss and enhancing their ability to grow in hot, dry climates.

CAM plants utilize Crassulacean acid metabolism (CAM) pathway for carbon fixation, storing carbon dioxide at night and using it during the day for photosynthesis.

CAM plants have adapted to manage water effectively by absorbing carbon dioxide at night and storing it as malic acid, minimizing water loss through transpiration.