The Light Reactions

For a deeper dive into this material, go to Topic 3.5, Part 4: The Light Reactions

1. Watch this Video

2. Study this Summary

What Do the Light Reactions Produce?

  • Convert light energy into chemical energy (ATP and NADPH).
    • ATP: Cellular energy currency.
    • NADPH: Electron carrier used to reduce carbon dioxide to glucose during in the Calvin cycle.
  • Oxygen is released as a waste product.

Where Do the Light Reactions Occur?

  • Take place in the thylakoid membranes of chloroplasts.
  • Key structures:
    • Photosystems: Protein-chlorophyll complexes that convert light energy into electrical energy.
    • Thylakoid space: Region where protons accumulate.

Inputs and Outputs of the Light Reactions

  • Inputs: Light, water, NADP⁺, ADP, and inorganic phosphate (Pi).
  • Outputs: ATP, NADPH
  • Waste product: oxygen.

How the Light Reactions Create ATP

  • Photoexcitation in photosystem II initiates electron flow through the electron transport chain (ETC).
  • ETC pumps protons from the stroma into the thylakoid space, creating a chemiosmotic gradient.
  • ATP synthase:
    • Protons diffuse back to the stroma through this enzyme.
    • Proton flow powers ATP synthesis from ADP and Pi.
  • Water-splitting complex in photosystem II:
    • Splits water into oxygen (waste product) and protons.
    • Enhances the proton gradient.

How the Light Reactions Create NADPH

  • Photoexcitation in photosystem I boosts electrons to a higher energy level.
  • Electrons flow through the ETC of photosystem I to the enzyme NADP⁺ reductase.
  • NADP⁺ reductase reduces NADP⁺ to NADPH by adding electrons and a proton.
  • NADPH provides reducing power for the Calvin cycle to synthesize carbohydrates.

The Z Scheme: Overview of the Light Reactions

  • The Z scheme is a graphical representation of electron energy levels during the light reactions.
  • Steps:
    • Light boosts electrons in photosystem II to a higher energy level.
    • Water is split, generating oxygen, protons, and electrons.
    • Electrons flow through the ETC of photosystem II, powering ATP synthesis.
    • Electrons arrive at photosystem I at a lower energy level.
    • Light boosts electrons in photosystem I to a higher energy level.
    • Electrons flow to NADP⁺ reductase, producing NADPH.
  • Products: ATP and NADPH.

3. Master these Flashcards

[qdeck style=”width: 600px !important; min-height: 450px !important;” bold_text=”false” random=”true”]

[h] The Light Reactions

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” dataset_id=”AP_Bio_Flashcards_2022|1c5a5fb288110″ question_number=”115″ topic=”3.5.Photosynthesis”] Describe how the light reactions of photosynthesis create ATP.

[a] Photoexcitation of chlorophyll in PS II starts a flow of electrons (b) along an electron transport chain in the thylakoid membrane. This powers proton pumping from the stroma (1) to the thylakoid space (2). This creates a chemiosmotic gradient that powers ATP synthesis as protons diffuse from the thylakoid space back to the stroma via an ATP synthase channel (i). Splitting of water by PS II (k) releases additional protons into the thylakoid space, enhancing the proton gradient for ATP creation.

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” topic=”3.5.Photosynthesis” dataset_id=”AP_Bio_Flashcards_2022|b56c0fecc1940″ question_number=”116″] The Calvin cycle involves the reduction of CO2 into carbohydrate. Describe how the light reactions create reducing power that can be used in the Calvin Cycle.

[a] Photoexcitation of chlorophylls in Photosystem I, which follows Photosystem II,  creates electron flow along the electron transport chain of PS I (f, above). These electrons flow to the enzyme NADP+ reductase, which reduces NADP+ into NADPH (at g). During the Calvin Cycle, NADPH provides the electrons and hydrogens to reduce CO2 to carbohydrates.

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” topic=”3.5.Photosynthesis” dataset_id=”AP_Bio_Flashcards_2022|b55a999393940″ question_number=”117″] The Z scheme is a kind of graphical shorthand of non-cyclic electron flow during the light reactions of photosynthesis. Create an illustrated sketch of the Z-scheme that shows the key processes in the light reactions.

[a] a. PS II antenna complex; b. light; c. reaction center; d. splitting water; e. photoexcitation; f. ETC of PS II; g. ADP and Pi; h. ATP, i. photoexcitation; j. ETC of PS I, K. NADP+, l. NADP+ reductase; m. NADPH, o. PS I antenna complex; p. PS I reaction center.

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” dataset_id=”AP_Bio_Flashcards_2022|1a3b5fb299210″ question_number=”118″ topic=”3.5.Photosynthesis”] What are the key inputs and outputs of the light reactions?

[a] Inputs: Light, water, NADP+, ADP, and inorganic phosphate (Pi).
Outputs: ATP, NADPH, and oxygen (as a waste product).

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” dataset_id=”AP_Bio_Flashcards_2022|1b3c6fb300910″ question_number=”119″ topic=”3.5.Photosynthesis”] Where do the light reactions occur, and what are the key structures involved?

[a] The light reactions occur in the thylakoid membranes of chloroplasts.
Key Structures:

  • Photosystems: Complexes of proteins and chlorophyll that absorb light and generate electron flow.
  • Electron transport chains: Transport electrons between photosystems and generate a proton gradient.
  • ATP synthase: Uses the proton gradient to synthesize ATP.

[q json=”true” yy=”4″ unit=”3.Cellular_Energetics” dataset_id=”AP_Bio_Flashcards_2022|1c4d7fb301110″ question_number=”120″ topic=”3.5.Photosynthesis”] What is the role of water in the light reactions?

[a] Water is split by the water-splitting complex in photosystem II, releasing:

  • Oxygen (as a waste product).
  • Protons, which enhance the proton gradient in the thylakoid space.
  • Electrons, which replace those lost by chlorophyll in photosystem II.

[/qdeck]

4. Tackle these Quizzes

Note that this quiz includes some big diagrams. You might have to adjust the display on your screen (Ctrl – on Windows, Command – on Mac) for them to fit on your screen). 

4.1. Light Reactions Quiz 1

[qwiz style=”width: 800px;” random = “false”]

[h]Light Reactions Quiz 1

[i]

[q labels = “top” dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|28b172673e49f” question_number=”1″]

 

[l]ATP synthesis

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]electron flow

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]proton accumulation

[fx] No. Please try again.

[f*] Great!

[l]proton pump

[fx] No. Please try again.

[f*] Excellent!

[l]reduction

[fx] No, that’s not correct. Please try again.

[f*] Correct!

[l]stroma

[fx] No. Please try again.

[f*] Excellent!

[l]thylakoid membrane

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]water splitting

[fx] No, that’s not correct. Please try again.

[f*] Correct!

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|28839bbd2589f” question_number=”7″]The region depicted at “1” is the [hangman]

[c]c3Ryb21h

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|287d349c7289f” question_number=”8″]The particle that’s getting pumped at  “c” is a [hangman]

[c]cHJvdG9u

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|2876a83b0149f” question_number=”9″]Chemically speaking, what’s happening to water at “k” is [hangman]

[c]b3hpZGF0aW9u

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|28701bd99009f” question_number=”10″]Chemically speaking, what’s happening to NADP+ at “g” is [hangman]

[c]cmVkdWN0aW9u

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|28698f781ec9f” question_number=”11″]The proton pumping at “c” is powered by a flow of [hangman]

[c]ZWxlY3Ryb25z

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|286248d2f649f” question_number=”12″]While the process at “c” is active transport, what’s happening at “i” is facilitated [hangman]

[c]ZGlmZnVzaW9u

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Photoexcitation, Photosystems, and Non-cyclic Electron Flow|2855c5130cc9f” question_number=”13″]The electrons used to reduce NADP+ at “g” ultimately come from [hangman]

[c]d2F0ZXI=[Qq]

[x][restart]

[/qwiz]

 

4.2. The Z Scheme

Note again that this quiz includes some big diagrams. You might have to adjust the display on your screen (Ctrl – on Windows, Command – on Mac) for them to fit on your screen). 

[qwiz style=”width: 800px;” random = “true” qrecord_id=”sciencemusicvideosMeister1961-Z-Scheme (2.0)”]

[h]The Z Scheme

[i]

[q labels = “top” dataset_id=”SMV_PSN_The Z scheme|28077b033a49f” question_number=”1″]

 

[l]electron transport chain

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]light

[fx] No. Please try again.

[f*] Good!

[l]Photosystem I

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]Photosystem II

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]splitting water

[fx] No, that’s not correct. Please try again.

[f*] Great!

[l]primary electron acceptor

[fx] No. Please try again.

[f*] Excellent!

[l]NADP+ reductase

[fx] No. Please try again.

[f*] Great!

[l]NADPH

[fx] No, that’s not correct. Please try again.

[f*] Good!

[q dataset_id=”SMV_PSN_The Z scheme|280113e28749f” question_number=”2″]In the diagram below, PS I is at

[textentry single_char=”true”]

[c]bw ==[Qq]

[f]WWVzLiBMZXR0ZXIg4oCcb+KAnSBpcyBQUyBJLg==[Qq]

[c]Kg==[Qq]

[f]Tm8uIFRoZSBwaG90b3N5c3RlbXMgaW5jbHVkZSB0aGUgY2hsb3JvcGh5bGwsIHRoZSBwcmltYXJ5IGFjY2VwdG9ycywgYW5kIHNvIG9uLiBJbiBhZGRpdGlvbiwgcmVtZW1iZXIgdGhhdCBpbiB0ZXJtcyBvZiBlbGVjdHJvbiBmbG93LCDCoFBTIDEgY29tZXMgYWZ0ZXI=IFBTIElJLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_The Z scheme|27faacc1d449f” question_number=”3″]In the diagram below, the primary electron acceptor for PS II is at

[textentry single_char=”true”]

[c]ZQ ==[Qq]

[f]WWVzLiBMZXR0ZXIg4oCcZeKAnSBpcyB0aGUgcHJpbWFyeSBlbGVjdHJvbiBhY2NlcHRvciBmb3IgUFMgSUku[Qq]

[c]Kg==[Qq]

[f]Tm8uIExvb2sgZm9yIHRoZSBpbml0aWFsICYjODIyMDtkZXN0aW5hdGlvbiYjODIyMTsgb2YgYW4gZWxlY3Ryb24gdGhhdCYjODIxNztzIGJlZW4gYm9vc3RlZCBieSBsaWdodCBlbmVyZ3kgaW4gUFMgSUkgKHdoaWNoLCBpbiB0ZXJtcyBvZiBlbGVjdHJvbiBmbG93LCBjb21lcyBiZWZvcmUgUFMgSSku

Cg==

[Qq]

[q dataset_id=”SMV_PSN_The Z scheme|27f420606309f” question_number=”4″]In the diagram below, the electron transport chain that provides the energy for making ATP is

[textentry single_char=”true”]

[c]Zg ==[Qq]

[f]QXdlc29tZS4gTGV0dGVyIOKAnGbigJ0gaXMgdGhlIGVsZWN0cm9uIHRyYW5zcG9ydCBjaGFpbiB0aGF0IHByb3ZpZGVzIHRoZSBlbmVyZ3kgdG8gY29udmVydCBBRFAgYW5kIFAgaW50byBBVFAu[Qq]

[c]Kg==[Qq]

[f]Tm8uIFRyeSB0byBmaW5kIHRoZSBlbGVjdHJvbiB0cmFuc3BvcnQgY2hhaW4gdGhhdCBjb25uZWN0cyBQaG90b3N5c3RlbSBJSSB3aXRoIFBob3Rvc3lzdGVtIEku

Cg==

[Qq]

[q dataset_id=”SMV_PSN_The Z scheme|27ecfefbf8c9f” question_number=”5″]In the diagram below, NADP+ reductase is

[textentry single_char=”true”]

[c]bA ==[Qq]

[f]QXdlc29tZS4gTGV0dGVyIOKAnGzigJ0gaXMgTkFEUA==Kw==IHJlZHVjdGFzZS4=[Qq]

[c]Kg==[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFlvdSYjODIxNztsbCBmaW5kIE5BRFA=Kw==IHJlZHVjdGFzZSBhdCB0aGUgZW5kIG9mIHRoZSBlbGVjdHJvbiB0cmFuc3BvcnQgY2hhaW4gYXNzb2NpYXRlZCB3aXRoIFBob3Rvc3lzdGVtIEku

Cg==
Cg==[Qq]

[x][restart]

[/qwiz]

4.3. The Light Reactions Quiz 3

[qwiz style=”width: 800px !important;” random = “true”]

[h]Cumulative Quiz: The Light Reactions

[i]

 

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27b771ea7cc9f” question_number=”1″] Which number or letter indicates the thylakoid membrane?

[textentry single_char=”true”]

[c]IG 8=[Qq]

[f]IFllcy4g4oCcb+KAnSBpcyB0aGUgdGh5bGFrb2lkIG1lbWJyYW5lLg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBNZW1icmFuZXMgYXJlIG1hZGUgb2YgcGhvc3Bob2xpcGlkcyBhbmQgcHJvdGVpbnMuIFRoZSBwaG9zcGhvbGlwaWRzIGFyZSBvcmdhbml6ZWQgaW50byBhIGJpbGF5ZXIgKHR3byBsYXllcnMpLiBXaGF0IGxvb2tzIGxpa2UgaXQgY291bGQgYmUgYXJyYW5nZWQgaW4gdHdvIGxheWVycz8=

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27b1300a8809f” question_number=”2″] Which number or letter shows the oxidation of chlorophyll in Photosystem II?

[textentry single_char=”true”]

[c]IG w=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGzigJ0gc2hvd3MgdGhlIG94aWRhdGlvbiBvZiBjaGxvcm9waHlsbCBpbiBQaG90b3N5c3RlbSAyLg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBGaW5kIFBob3Rvc3lzdGVtIDIuIFRoZW4gZmluZCBhbiBhcnJvdyBtb3ZpbmcgZnJvbSBjaGxvcm9waHlsbCBpbiB0aGUgcmVhY3Rpb24gY2VudGVyIHRvIGEgcHJpbWFyeSBlbGVjdHJvbiBhY2NlcHRvcg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27ab832d8c49f” question_number=”3″] Which number or letter indicates the electron transport chain that powers proton pumping from the stroma to the thylakoid space?

[textentry single_char=”true”]

[c]IG I=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGLigJ0gc2hvd3MgdGhlIGVsZWN0cm9uIHRyYW5zcG9ydCBjaGFpbiB0aGF0IHBvd2VycyB0aGUgcHVtcGluZyBvZiBwcm90b25zIGZyb20gdGhlIHN0cm9tYSB0byB0aGUgdGh5bGFrb2lkIHNwYWNlLg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIGEgcHJvdG9uIChIKw==KSBtb3ZpbmcgZnJvbSB0aGUgc3Ryb21hICgxKSB0byB0aGUgdGh5bGFrb2lkIHNwYWNlICgyKS4gTm93IGZpbmQgdGhlIGFycm93IHRoYXQgaW5kaWNhdGVzIHRoZSBlbGVjdHJvbiBmbG93IHRoYXQgcG93ZXJzIHRoYXQgcHVtcC4=

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27a58bcf1409f” question_number=”4″] Which number or letter indicates the pumping of protons from the stroma to the thylakoid space?

[textentry single_char=”true”]

[c]IG M=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGPigJ0gc2hvd3MgdGhlIHB1bXBpbmcgb2YgcHJvdG9ucyBmcm9tIHRoZSBzdHJvbWEgKDEpIHRvIHRoZSB0aHlsYWtvaWQgc3BhY2UgKDIp[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIGEgcHJvdG9uIChIKw==KSBtb3ZpbmcgZnJvbSB0aGUgc3Ryb21hICgxKSB0byB0aGUgdGh5bGFrb2lkIHNwYWNlICgyKS4=

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|279fb9b15a09f” question_number=”5″] Which number or letter indicates the enzyme-catalyzed creation of the reduced, mobile electron carrier that brings reducing power to the Calvin cycle.

[textentry single_char=”true”]

[c]IG c=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGfigJ0gc2hvd3MgdGhlIGVuenltZSBOQURQKw==IHJlZHVjdGFzZSBjb252ZXJ0aW5nIE5BRFA=Kw==IHRvIE5BRFBILg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhIG1vbGVjdWxlIHRoYXQmIzgyMTc7cyBhY2NlcHRpbmcgYW4gZWxlY3Ryb24gKGFuZCBhIHByb3RvbiksIGNvbnZlcnRpbmcgaXQgaW50byBvbmUgb2YgdGhlIHR3byBrZXkgb3V0cHV0cyBvZiB0aGUgbGlnaHQgcmVhY3Rpb25zLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|2799e793a009f” question_number=”6″] Which number or letter indicates the accumulation of protons that powers the synthesis of ATP?

[textentry single_char=”true”]

[c]IG o=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGrigJ0gc2hvd3MgcHJvdG9uIGJ1aWxkdXAgaW5zaWRlIHRoZSB0aHlsYWtvaWQgc3BhY2UgZnJvbSB0aGUgc3BsaXR0aW5nIG9mIHdhdGVyICgmIzgyMjA7ayYjODIyMTspIGFuZCBwcm90b24gcHVtcGluZyBieSBwaG90b3N5c3RlbSAyJiM4MjE3O3MgZWxlY3Ryb24gdHJhbnNwb3J0IGNoYWluICgmIzgyMjA7YyYjODIyMTsp[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhbiBhcnJvdyBvciByZWdpb24gaW4gdGhlIGRpYWdyYW0gdGhhdCBzaG93cyB0aGUgYWNjdW11bGF0aW9uIG9mIHByb3RvbnMgZnJvbSB0aGUgc3BsaXR0aW5nIG9mIHdhdGVyLCBhbmQgZnJvbSB0aGUgcHVtcGluZyBvZiBwcm90b25zICh3aGljaCBpcyBzaG93biBhdCAmIzgyMjA7YyYjODIyMTspLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|2793caf46989f” question_number=”7″] Which number or letter indicates the reaction that’s the source of all of the oxygen in our atmosphere?

[textentry single_char=”true”]

[c]IG s=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGvigJ0gc2hvd3MgdGhlIHNwbGl0dGluZyBvZiB3YXRlciAoJiM4MjIwO2smIzgyMjE7KSwgd2hpY2ggcmVzdWx0cyBpbiBwcm90b25zLCBlbGVjdHJvbnMgKHdoaWNoIGdldCB1c2VkIGluIHBob3Rvc3ludGhlc2lzKSwgYW5kIG94eWdlbiAod2hpY2ggYnViYmxlcyBvdXQgb2YgdGhlIGNobG9yb3BsYXN0IGFuZCBpbnRvIG91ciBhdG1vc3BoZXJlKQ==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhbiBhcnJvdyBvciByZWdpb24gaW4gdGhlIGRpYWdyYW0gdGhhdCBzaG93cyB0aGUgcHJvZHVjdGlvbiBvZiBveHlnZW4gKE8=Mg==KQ==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|278df8d6af89f” question_number=”8″] Which number or letter indicates the region of the chloroplast that would have a very low pH?

[textentry single_char=”true”]

[c]ID I=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnDLigJ0gaW5kaWNhdGVzIHRoZSB0aHlsYWtvaWQgc3BhY2UuIEJlY2F1c2UgcHJvdG9ucyBhcmUgYmVpbmcgcHVtcGVkIGludG8gdGhpcyByZWdpb24sIGl0IHdpbGwgaGF2ZSBhIGxvdyBwSCAoYmVjYXVzZSBsb3cgcEggbWVhbnMgaGlnaCBwcm90b24gY29uY2VudHJhdGlvbiku[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciB0aGUgcmVnaW9uIHdoZXJlIHByb3RvbnMgYXJlIGFjY3VtdWxhdGluZy7CoEJlY2F1c2UgcHJvdG9ucyBhcmUgYmVpbmcgcHVtcGVkIGludG8gdGhpcyByZWdpb24sIGl0IHdpbGwgaGF2ZSBhIGxvdyBwSCAoYmVjYXVzZSBsb3cgcEggbWVhbnMgaGlnaCBwcm90b24gY29uY2VudHJhdGlvbiku

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27884bf9b3c9f” question_number=”9″] Which number or letter indicates the primary electron acceptor of Photosystem I?

[textentry single_char=”true”]

[c]IG k=[Qq]

[f]IFllcy4gVGhlIGxldHRlciDigJxp4oCdIGluZGljYXRlcyB0aGUgcHJpbWFyeSBlbGVjdHJvbiBhY2NlcHRvciBvZiBQaG90b3N5c3RlbSAxLg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBGaWd1cmUgb3V0IHdoaWNoIHBob3Rvc3lzdGVtIGlzIFBob3Rvc3lzdGVtIDEuIFRoZW4gZmluZCB0aGUgcG9pbnQgaW4gdGhhdCBzeXN0ZW0gd2hlcmUgZWxlY3Ryb25zIGhhdmUgdGhlaXIgaGlnaGVzdCBlbmVyZ3kgbGV2ZWwu

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27829f1cb809f” question_number=”10″] Which letter indicates the source of all of the electrons involved in the light reactions of photosynthesis?

[textentry single_char=”true”]

[c]IG Q=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGTigJ0gaW5kaWNhdGVzIHdhdGVyLCB3aGljaCBpcyB0aGUgc291cmNlIG9mIGFsbCBvZiB0aGUgZWxlY3Ryb25zIGludm9sdmVkIGluIHRoZSBsaWdodCByZWFjdGlvbnMu[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBXb3JrIGJhY2t3YXJkIHRvIGZpbmQgdGhlIGZpcnN0IGVsZWN0cm9ucyB0aGF0IGdldCBib29zdGVkIGJ5IGxpZ2h0IGluIFBob3Rvc3lzdGVtIElJLiBXaGVyZSBhcmUgdGhvc2UgZWxlY3Ryb25zIGNvbWluZyBmcm9tPw==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|277cf23fbc49f” question_number=”11″] Which letter indicates the reaction center for Photosystem II?

[textentry single_char=”true”]

[c]IG M=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGPigJ0gaW5kaWNhdGVzIHA2ODAsIHdoaWNoIGlzIHBob3Rvc3lzdGVtIElJJiM4MjE3O3MgcmVhY3Rpb24gY2VudGVyLg==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBGaW5kIFBob3Rvc3lzdGVtIElJLiBOb3cgZmluZCB0aGUgbGFzdCBjaGxvcm9waHlsbCBtb2xlY3VsZSB0aGF0JiM4MjE3O3MgaW4gdGhlIGNoYWluIG9mIGVuZXJneSB0cmFuc2ZlcnMgdGhhdCBsZWFkcyB0byBlbGVjdHJvbnMgYmVpbmcgdHJhbnNmZXJyZWQgdG8gYSBwcmltYXJ5IGVsZWN0cm9uIGFjY2VwdG9yLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27774562c089f” question_number=”12″] Which letter indicates ATP?

[textentry single_char=”true”]

[c]IG g=[Qq]

[f]IFllcy4gTGV0dGVyIOKAnGjigJ0gaW5kaWNhdGVzIEFUUA==[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBBVFAgc3ludGhlc2lzIGlzIHBvd2VyZWQgYnkgdGhlIGVsZWN0cm9uIHRyYW5zcG9ydCBjaGFpbiB0aGF0IGJyaW5ncyBlbGVjdHJvbnMgZnJvbSBQaG90b3N5c3RlbSBJSSB0byBQaG90b3N5c3RlbSBJLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|276ca5ec8049f” question_number=”14″] During the light reactions, protons get pumped into this space.

[textentry single_char=”true”]

[c]ID U=[Qq]

[f]IFllcy4gRHVyaW5nIHRoZSBsaWdodCByZWFjdGlvbnMsIHByb3RvbnMgYXJlIHB1bXBlZCBmcm9tIHRoZSBzdHJvbWEgdG8gdGhlIHRoeWxha29pZCBzcGFjZSAoYXQgJiM4MjIwOzUuJiM4MjIxOyk=[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBUaGUgcHVtcGluZyBvZiBwcm90b25zIGFzc29jaWF0ZWQgd2l0aCBBVFAgc3ludGhlc2lzIGFsd2F5cyBpbnZvbHZlcyBwdW1waW5nIHRoZW0gaW50byBhbiBlbmNsb3NlZCBzcGFjZS4gV2hhdCB0aW55IGVuY2xvc2VkIHNwYWNlcyBhcmUgc2hvd24gb24gdGhpcyBkaWFncmFtPw==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27671e5042c9f” question_number=”15″] The pH of this fluid is significantly higher (less acidic) than the pH in the thylakoid space.

[textentry single_char=”true”]

[c]ID Y=[Qq]

[f]IFllcy4gRHVyaW5nIHRoZSBsaWdodCByZWFjdGlvbnMsIHByb3RvbnMgYXJlIHB1bXBlZCBmcm9tIHRoZSBzdHJvbWEgdG8gdGhlIHRoeWxha29pZCBzcGFjZSAoYXQgJiM4MjIwOzUuJiM4MjIxOykgVGhpcyBsb3dlcnMgdGhlIHBIIGluIHRoZSB0aHlsYWtvaWQgc3BhY2UsIGFuZCByYWlzZXMgdGhlIHBIIGluIHRoZSBzdHJvbWEgKCYjODIyMDs2JiM4MjIxOyku[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBUaGUgcHVtcGluZyBvZiBwcm90b25zIHRoYXQmIzgyMTc7cyBhc3NvY2lhdGVkIHdpdGggQVRQIHN5bnRoZXNpcyBtb3ZlcyBwcm90b25zIGludG8gdGhlIHRoeWxha29pZCBzcGFjZSAobG93ZXJpbmcgdGhlIHBIIHRoZXJlKSBhbmQgb3V0IG9mIHRoZSBzdHJvbWEsIChyYWlzaW5nIHRoZSBwSCB0aGVyZSku

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|276206764009f” question_number=”16″] A by-product that results from the splitting of water that occurs during the light reactions

[textentry single_char=”true”]

[c]ID M=[Qq]

[f]IFllcy4gVGhlIHNwbGl0dGluZyBvZiB3YXRlciBjcmVhdGVzIG94eWdlbiAoJiM4MjIwOzMmIzgyMjE7KSB3aGljaCBpcyBhIGJ5LXByb2R1Y3Qgb2YgdGhlIGxpZ2h0IHJlYWN0aW9ucy4=[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBCZWNhdXNlIHRoaXMgaXMgYSBieS1wcm9kdWN0LCBsb29rIGZvciBzb21ldGhpbmcgdGhhdCYjODIxNztzIGxlYXZpbmcgdGhlIGxpZ2h0IHJlYWN0aW9ucywgd2hpY2ggaXMgdGhlcmVmb3JlIG5vdCBjb250cmlidXRpbmcgdG8gdGhlIG5leHQgcGhhc2Ugb2YgcGhvdG9zeW50aGVzaXMgKHRoZSBDYWx2aW4gY3ljbGUpLg==

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|275c7eda0289f” question_number=”17″] The source of the electrons in the light-powered electrical current that is part of the light reactions.

 

[textentry single_char=”true”]

[c]ID I=[Qq]

[f]IFllcy4gTnVtYmVyICYjODIyMDsyJiM4MjIxOyByZXByZXNlbnRzIHdhdGVyLCB0aGUgc291cmNlIG9mIHRoZSBlbGVjdHJvbnMgaW52b2x2ZWQgaW4gdGhlIGxpZ2h0IHJlYWN0aW9ucy4=[Qq]

[c]ICo=[Qq]

[f]IE5vLiBIZXJlJiM4MjE3O3MgYSBoaW50LiBMb29rIGZvciBhbiBpbnB1dCBvZiBtYXR0ZXIgKG5vdCBlbmVyZ3kpIHRvIHRoZSBsaWdodCByZWFjdGlvbnMgKHRoZXJlJiM4MjE3O3Mgb25seSBvbmUpLg==

Cg==

IA==[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|2756877b8a49f” question_number=”18″] During the light reactions, the energy of electrons powers the pumping of[hangman]from the stroma to the thylakoid space.

[c]IHByb3RvbnM=

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|2750ffdf4cc9f” question_number=”19″] The flow of protons from the thylakoid space to the stroma occurs through [hangman] diffusion.

[c]IGZhY2lsaXRhdGVk

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|274b53025109f” question_number=”20″] In the light reactions, ATP is synthesized as protons diffuse through an ATP [hangman] channel.

[c]IHN5bnRoYXNl

Cg==

[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27463b284e49f” question_number=”21″] The pumping of protons from the stroma into the thylakoid space occurs through [hangman] transport.

[c]IGFjdGl2ZQ==

Cg==

IA==[Qq]

[q dataset_id=”SMV_PSN_Light Reactions Cumulative|27408e4b5289f” question_number=”22″] The enzyme that converts NADP+ into NADPH is called NADP+ [hangman]

[c]IHJlZHVjdGFzZQ==[Qq]

[x][restart]

[/qwiz]


What’s Next?

Please proceed to the next tutorial: The Calvin Cycle