Exam 2 - Light Reaction Flashcards
What happens in Step 1 of the Light Reaction?
Light is absorbed at Photosystem II, the first reaction center. Energy excites an electron pair and transfers them to an electron acceptor. The electron pair is replenished by splitting H2O into ½ O2.
What is the role of the primary electron acceptor in the Light Reaction?
The primary electron acceptor receives the excited electron pair from Photosystem II.
What occurs in Step 2 of the Light Reaction?
An electron carrier moves the pair of electrons down an electron transport chain (ETC).
How does the electron transport chain (ETC) function?
The ETC works like a hydroelectric dam, where stored water flows out to spin a turbine that generates electricity.
What is the role of the electron carrier in the light reaction?
The electron carrier moves a pair of electrons down an electron transport chain (ETC).
What happens as the electron pair passes through the ETC?
It uses energy to pump H+ into the thylakoid membrane interior space.
What is formed as H+ builds up on one side of the membrane?
A proton gradient forms.
What is the relationship between the light reaction and the Calvin cycle?
There is no Calvin cycle during the light reaction.
Where does ATP synthase operate in the light reaction?
Inside the thylakoid membrane.
What happens to the electron pair as it passes through the ETC?
It uses energy to pump a H+ into the thylakoid membrane interior space.
What is the most abundant type of electron flow in the membranes?
Noncyclic electron flow.
Where is NADPH synthesized?
In the chloroplast stroma.
What builds up a lot of H+ on one side of the membrane?
The transport of electrons through the ETC.
What type of transport occurs in the ETC?
Active transport.
What is fueling the transport of H+?
The energy from the electron transport chain.
Where does the Calvin cycle take place?
In the stroma of the chloroplast.
What is the location of the thylakoid?
Inside the thylakoid membrane.
What flows down a concentration gradient through the ATPase synthase?
H+
H+ ions pass through the channel in the ATPase synthase.
What happens as H+ pass through the ATPase synthase?
A conformational change occurs, causing ATP to form.
What is the process called that involves noncyclic electron flow?
Noncyclic electron flow is a process in photosynthesis.
Where does the noncyclic electron flow occur?
In the chloroplast stroma.
What are the inputs for the noncyclic electron flow?
NADP+ and ADP + Pi.
What is the role of Photosystem II in the light reaction?
Photosystem II is involved in the noncyclic electron flow.
What is the primary electron acceptor in the light reactions?
NADP+
NADP+ is reduced to NADPH.
What happens to the electron pair in Photosystem I?
The electron pair is transferred to NADH to carry the electrons away.
What is produced by the NADPH-producing photosystem?
NADPH is produced.
What is absorbed at the reaction center of Photosystem I?
Light is absorbed.
What is formed during the light reactions?
A proton gradient is formed.
Does the light-dependent reactions require ATP to run?
False. The light-dependent reactions produce ATP, they do not require it to run.
Does water donate the electrons used in the ETC?
True.
Does ATPase synthase make ATP by absorbing sunlight?
False. ATPase synthase makes ATP by utilizing the proton gradient.
Has glucose been formed by the end of the ETC?
False. Glucose is not formed in the light-dependent reactions.
What is the primary electron acceptor in the light reactions?
NADP+
NADP+ is reduced to NADPH.
What happens to the electron pair in Photosystem I?
The electron pair is transferred to NADH to carry the electrons away.
What is produced by the NADPH-producing photosystem?
NADPH is produced.
What is absorbed at the reaction center of Photosystem I?
Light is absorbed.
What is formed during the light reactions?
A proton gradient is formed.
Does the light-dependent reactions require ATP to run?
False. The light-dependent reactions produce ATP, they do not require it to run.
Does water donate the electrons used in the ETC?
True.
Does ATPase synthase make ATP by absorbing sunlight?
False. ATPase synthase makes ATP by utilizing the proton gradient.
Has glucose been formed by the end of the ETC?
False. Glucose is not formed in the light-dependent reactions.
What is the first step of the Calvin cycle?
Carbon fixation - A 5-C sugar RuBP is attached to CO₂ to make two 3-C molecules.
What inputs are required for the carbon fixation step?
CO₂, Rubisco, and RuBP.
What is the second step of the Calvin cycle?
Reduction - Using energy from ATP & NADPH & enzymes, a 3-C sugar called G3P is formed.
What inputs are required for the reduction step?
CO₂, Rubisco, and RuBP.
What is the third step of the Calvin cycle?
Release of G3P - G3P leaves the cycle and will go on to form glucose.
What inputs are required for the release of G3P step?
Rubisco and 3-PGA.
What is G3P?
G3P (glyceraldehyde 3-phosphate) is a 3-C sugar formed during the Calvin cycle.
