Untitled Flashcards Set

What are the two types of photophosphorylation during the light-dependent reaction?

Cyclic and non-cyclic photophosphorylation.

Where do light-dependent reactions occur in chloroplasts?

In the thylakoid membranes.

What are the two photosystems involved in non-cyclic photophosphorylation?

PSI and PSII.

What is the role of light energy in non-cyclic photophosphorylation?

It excites electrons in the chlorophyll of PSII.

What is photoionisation of chlorophyll?

The process where light energy excites electrons in chlorophyll.

What type of proteins are electron carriers in the thylakoid membranes?

They are proteins that transfer electrons between PSI and PSII.

What is the electron transport chain (ETC)?

A series of electron carriers that transfer high-energy electrons.

How is a proton gradient formed during non-cyclic photophosphorylation?

Electrons moving down the ETC pump protons from the stroma into the thylakoids.

What is chemiosmosis?

The process where protons diffuse down their gradient through ATP synthase, converting ADP and inorganic phosphate to ATP.

What is produced during non-cyclic photophosphorylation?

Reduced NADP and ATP.

How are electrons replaced in PSII during non-cyclic photophosphorylation?

By photolysis of water.

What is photolysis?

The process of splitting water into protons, electrons, and oxygen using light energy.

What happens to electrons released from PSI in non-cyclic photophosphorylation?

They are transferred directly to NADP, not passed through the ETC.

How do electrons move in cyclic photophosphorylation?

They cycle continuously through the electron carriers to PSI.

What is the main difference in electron movement between cyclic and non-cyclic photophosphorylation?

Cyclic photophosphorylation does not involve PSII and recycles electrons.

What occurs when high-energy electrons move down the electron transport chain?

They lose energy, which is used to pump protons across the membrane.

What role does ATP synthase play in phosphorylation?

It synthesizes ATP from ADP and inorganic phosphate when protons diffuse through it.

What does non-cyclic photophosphorylation generate in addition to ATP?

Reduced NADP.

What does cyclic photophosphorylation lack compared to non-cyclic photophosphorylation?

It does not produce reduced NADP.

In cyclic photophosphorylation, what happens to the electrons after they are excited?

They are recycled back to PSI.

What is the relationship between photon energy and electron energy levels?

Light energy increases the energy levels of electrons.

What is created when protons accumulate inside the thylakoids?

A proton gradient.

Why is non-cyclic photophosphorylation important in photosynthesis?

It produces both ATP and reduced NADP, necessary for the Calvin cycle.

What energy transformation occurs during chemiosmosis?

The potential energy of the proton gradient is converted into chemical energy in the form of ATP.

What is the consequence of photolysis for PSII?

Electrons released from water split replace those used in PSII.

In non-cyclic photophosphorylation, what do high-energy electrons from PSII ultimately help to create?

ATP and reduced NADP.

What type of energy triggers the absorption of light by PSI in cyclic photophosphorylation?

Light energy.

In non-cyclic photophosphorylation, what are the end products of the light-dependent reactions?

ATP and NADPH.

What happens to the protons pumped into the thylakoid lumen during the electron transport chain process?

They create a proton-motive force that drives ATP synthesis.

How does cyclic photophosphorylation conserve resources?

By recycling electrons and producing ATP without the need for photolysis.

What is the fate of oxygen produced in photolysis?

It is released as a by-product into the atmosphere.