ap biology frq photosynthesis

Excel at Science

• Feb 16, 2021

AP Biology Past FRQs by Topic

Updated: Jan 31

**Updated on 1/31/24 to include the 2022-23 FRQ exams!**

If you are looking for past AP Biology free-response questions (FRQs) that are organized by topic, then you have come to the right place. In this post, we have linked every freely available past FRQ there is from College Board and organized it into the following major topics of AP Biology .

(Please note that we are not associated with College Board and are simply sharing the resources they have made available to students.)

Biochemistry

Metabolism & energetics.

Physiology (note that this topic will not be tested on the official AP Biology exam this year in 2021, although many questions about physiology could also cover concepts that will be tested)

Experiment design & data analysis

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Intensively doing and reviewing practice questions is proven to be much more effective than spending hours studying. Check out our AP Bio Practice Portal , which is an easy-to-use database of 300+ AP-style MCQ and FRQ practice questions. Students love the Practice Portal because it includes answers and explanations for every problem, tracks progress, and saves time from Googling practice problems.

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How to make the most of past frqs from college board.

As noted above, the diversity of organisms, plants, and physiology will not be on the 2021 AP Biology exam. However, the exam could include questions about topics or hypothetical situations that are related to those topics. One great example is cell communication, which is used in multiple systems inside our bodies. Let’s say an FRQ was to appear about the immune system and how the immune cells communicate. That would be fair game as long as the question focuses on the cell signaling part, not the details of the immune system. If the question requires some background knowledge about the immune system, it will be provided.

If you want to do a whole practice FRQ set just like the ones on the real exam (which we highly recommend), all the freely available past FRQs by year are available here on the College Board website. Tip: time yourself and take the practice FRQ set in an environment that mimics how you imagine your actual testing environment to be.

If you would like to focus on a particular topic, then the section coming up is for you. Some FRQs will show up under multiple topics because they truly do test students’ understanding of multiple different topics.

Tip : Whether you are doing individual free-response questions or doing a full problem set in one go, it is extremely important and effective to do test corrections! Don’t only consult the scoring guidelines and model responses when you have no clue how to answer a question. You should be checking them for all the FRQs you do. When you find a difference between your answer and the scoring guidelines, it is important that you pause and analyze why your response is incorrect. Take the time to understand your mistakes and see how your answer could have been better. This will help you boost your scores the most efficiently.

AP BIOLOGY FRQs BY TOPIC

Below are the linked FRQs organized by topic. The header for each topic will also lead you to the corresponding study guide that will help you review the unit in detail!

Basic and organic chemistry concepts do not come up often on the FRQs (but of course, it’s better to be prepared). The properties of water and macromolecules come up occasionally.

2017 #7 and 8

Includes cell structure and function, cell transport and the proteins involved.

2019 #3 and 8

2018 #2, 6, and 8

2006 #1, 3, and 4

2001 #1 and 4

(study guide coming soon!)

This unit includes enzymes, cellular respiration, and photosynthesis.

2023 #2 (cell respiration & photosynthesis)

2023 #4 (photosynthesis)

2022 #3 (enzymes)

2021 #3 (cell respiration)

2019 #3 (cell respiration)

2018 #2 (cell respiration)

2017 #7 (cell respiration)

2017 #5 (photosynthesis)

2015 #2 (cell respiration)

2013 #2 (photosynthesis) and 4 (cell respiration & photosynthesis)

2012 #2 (cell respiration) and 4 (cell respiration & photosynthesis)

2010 #2 (enzymes)

2007 #3 (photosynthesis)

2006 #4 (photosynthesis)

2005 #1 (cell respiration & photosynthesis)

2004 #3 (photosynthesis)

Cell cycle & cell signaling

This topic has shown up more frequently and in more difficult FRQs in recent years, especially cell communication. The trend will most likely continue so definitely prioritize reviewing and practicing this topic!

2023 #1 (cell communication)

2022 #1 (cell communication)

2022 #2 (cell cycle, meiosis)

2021 #1 (cell communication)

2019 #4 (cell communication)

2018 #8 (cell communication)

2017 #8 (cell communication)

2016 # 7 (cell division)

2015 # 4 (cell division)

2015 #5 and 7 (cell communication)

2013 #8 (cell communication)

2011 #1B (cell division)

2010 #1 (cell communication)

2006 #1B (cell division)

2004 #1 (cell division)

Genetics, Gene Expression and Regulation

Genetics Pt 1 and Genetics Pt 2 Study Guides

This section includes the classic Mendelian genetics, with Punnett squares, crosses, and Mendel’s laws. It also includes DNA replication, protein synthesis, and gene expression regulation for both eukaryotes and prokaryotes.

2023 #6 (gene expression)

2022 #6 (protein synthesis, gene expression)

2021 #6 (gene expression)

2021 #2 (heredity + pedigrees)

2020 #1 parts a-b

2019 #1 and 3

2018 #1, 4, and 7

2016 #4 and 7

2023 #5 (Cladistics)

2022 #4 (speciation)

2020 #1 parts f-j

2015 #3 and 6

2014 #2 and 4

2015 #2 (nervous system)

2014 #2 (immune system) and 6 (musculoskeletal system) and 7

2017 #2, 4, and 7b

2016 #3 and 5

2014 #3 and 4

Experimental design & analysis

This is an additional section that isn’t focused on any particular topic or has significant data analysis involved. While most FRQs do pertain to a specific topic(s), some are simply there to test your knowledge of experimental design and understanding of statistical concepts such as performing Chi-Square tests and interpreting error bars on graphs. These types of questions have become more and more common on the AP exam, so it is important to feel comfortable and confident with them.

2023 #6 (data analysis)

2022 #3 (experiment design)

2020 #1 parts c-e

2016 #2 , 6 and 8

2014 #1 and 5

2013 #1 and 7

Hope these organized FRQs saved you some time so you can focus more on actually doing them and practicing! You can easily share this post with friends who may find it helpful as well.

How to Improve AP Biology FRQ Scores, Fast

Do a lot of FRQ practice problems and review the answers! Practice is key, especially for a subject as dense as AP Bio. Check out the AP Bio Practice Portal , which is our popular vault of 300+ AP-style MCQ and FRQ problem sets with answers and explanations for every question. Don't waste any more time Googling practice problems or answers - try it out now!

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AP Biology : 3.5 Photosynthesis- Exam Style questions with Answer- FRQ

AP Physics AP Calculus AP Chemistry AP Biology

The sea slug Elysia crispata eats photosynthetic algae. However, after consuming the algae, the chloroplasts from the algae are incorporated into the sea slug’s own cells, give the sea slug a green color, and remain functional for up to four months. This phenomenon is called kleptoplasty. (a) Describe the role of photosynthetic algae in ecosystems. (b) Explain why kleptoplasty would give Elysia crispata a survival advantage. (c) An oil spill on the surface of the water reduces the intensity of light in Elysia crispata’s habitat. Predict the effect this would have on Elysia crispata’s survival. (d) Justify your prediction from part (c).

(a) Photosynthetic algae are autotrophs—they make their own food

and are consumed by other organisms. (b) Kleptoplasty would give Elysia crispata a survival advantage because the chloroplasts that remained functional in the Elysia crispata’s cells would provide the sea slug with food. (c) Reducing the intensity of light in Elysia crispata’s habitat would have a negative impact on Elysia crispata’s survival. (d) Photosynthesis requires light energy, so reducing the light intensity would reduce the amount of photosynthesis the chloroplasts would perform and the amount of food from those chloroplasts that would be available to Elysia crispata. The sea slug might become more dependent on consuming other food sources.

(c) Rubisco is an enzyme that is used in the light-independent reactions (the Calvin cycle) of photosynthesis, so the light-independent reactions would be most directly affected by an inhibitor of Rubisco.

(d) The light-independent reactions of photosynthesis require ATP and NADPH that are produced by the light-dependent reactions of photosynthesis. If a plant was kept in the dark for a long period of time, the light-dependent reactions would stop and the ATP and NADPH that are required for the light-independent reactions would not be produced. Thus, the light-independent reactions would stop when their supply of ATP and NADPH was depleted.

Calculate the rate of photosynthesis in both sets of plants during the first 30 minutes of the experiment. (d) Plants that use carotenoids as their primary photosynthetic pigment are grown under three different wavelengths of light: 450 nm, 500 nm, and 550 nm. Predict which group of plants will perform the least amount of photosynthesis, and justify your prediction.

(a) Chlorophyll a will absorb the most violet light because its peak absorbance is at approximately 425 nm, which is in the range for violet. Chlorophyll b will absorb the most blue light because its peak absorbance is at approximately 480 nm, which is in the range for blue. The carotenoids absorb the most green light because their peak absorbance is at approximately 510 nm, which is in the range for green. (b) An appropriate control would be a plant without the mutation that could produce chlorophyll a, chlorophyll b, and carotenoids. The independent variable would be the presence or absence of chlorophyll a and chlorophyll b. The dependent variable would be the rate of photosynthesis. (c) Rate of photosynthesis in the control plants = 400 microliters oxygen/30 minutes = 13.3 microliters oxygen/minute Rate of photosynthesis in the plants with the mutation = 100 microliters oxygen/30 minutes = 3.3 microliters oxygen/minute (d) The plants grown under light with a wavelength of 550 nm will perform the least amount of photosynthesis because carotenoids absorb the least amount of light energy at 550 nm. The absorbance is greater at 450 nm and 500 nm than it is at 550 nm, so less photosynthesis will occur at 550 nm.

AP Biology Practice Tests

The AP Biology Exam is 3 hours long and is divided into two sections: Section I (multiple-choice questions) and Section II (free-response questions).

The AP biology exam assesses content from each of four big ideas for the course:

1. Evolution 2. Energetics 3. Information Storage and Transmission 4. Systems Interactions

• How to Approach AP Biology Multiple-Choice Questions
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The details of the AP biology exam, including exam weighting and timing, can be found below:

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AP® Biology

Photosynthesis: ap® biology crash course.

• The Albert Team
• Last Updated On: March 1, 2022

There’s a lot of information in the Advanced Placement (AP) Biology photosynthesis unit that can distract you from remembering its most important concept: the transformation of light energy into chemical energy, and then its storage in the bonds of carbohydrates.

Instead of giving you a laundry list of processes and reactions, we are going to discuss the pathway of light energy in plants. We think a pathway is easier to remember and maintains the focus on energy transduction.

LIGHT: THE DRIVING FORCE OF PHOTOSYNTHESIS

When light hits an object, photons are reflected, transmitted, or absorbed. The term photon  here emphasizes the particle-like behavior of light, as opposed to the wave-like behavior of light. Reflection and transmission constitute what we perceive as color. Absorption is what allows photosynthesis.

Plants take advantage of the fact that some photons can be absorbed and use the energy of these photons for photosynthesis. This energy conversion takes place in the chloroplasts of the plant cell, where light energy is converted to chemical energy. Photons with more energy than a given electron in the chloroplast will transfer energy to the electron by the mechanism of diffusion. The electron then acts as an energy carrier, transferring its energy to be used for many reactions in photosynthesis.

We say that light is the driving force behind photosynthesis because light is the original provider of the energy used in the photosynthetic process. The first set of reactions in photosynthesis are called “light-dependent” reactions because they need light energy to start and continue. The second set of reactions are known as “light-independent” reactions as they function using the energy produced by the first set of reactions, but not the photons themselves.

We will highlight the key points you need to understand to fully take advantage of this surprisingly simple AP® Biology photosynthesis exploration. The first time, read through as if you are reading a story; this will give you the bigger picture, and it will help you avoid getting lost in the jargon. Next, read again focusing on the details; always keep in mind what the purpose of each system, enzyme and molecule is. This will help you understand the concepts instead of cramming for your AP® Biology exam.

THE LIGHT-DEPENDENT PHASE

Light absorption.

Once light energy (in the form of photons) has been absorbed by the chlorophyll and other pigments of the chloroplast, this energy needs to go somewhere. The energy is transferred to the photo systems of the chloroplast – bundles of chlorophyll pigments packed into thylakoids. Thylakoids are membrane-bound sacs inside chloroplasts where the light-dependent reactions of photosynthesis occur. The energy is carried by electrons; these electrons are known in this state as “excited” electrons. The excited electrons concentrate in the thylakoid membrane proteins, which power photosynthesis. The photosynthetic process begins in Photo system II – so called because this photo system was the second photo system discovered (don’t get confused – Photo system I is used later in photosynthesis!).

In Photo system II, light energy from photons splits water into its constituents:two H + ions,two electrons, and a single oxygen atom in a process known as photolysis. The electrons released are transferred to P680 molecules while the oxygen atoms combine to form O 2 , which is released into the atmosphere, and the H + molecules remain in the thylakoid membrane for later use in the conversion of NADP + to NADPH (remember this – we will come back to it later). P680 is a bundle of chlorophyll pigments located within Photo system II that acts as an oxidizing agent (currently no stronger oxidizing agent is known to exist!). The first stage of this reaction, the photolysis of water, occurs as follows:

2H 2 O ®4H + + O 2 + 4e –   

THE ELECTRON TRANSPORT CHAIN

At this stage, we introduce the electron transport chain, which is the mechanism by which electrons are transferred from the thylakoid membrane proteins to the NADP + molecule – all of this occurs to produce ATP and water necessary for the plant’s growth. The beginning of transport chain is Photo system II, where electrons are first excited by light. Electrons released by the reduction of NADH 2  then progress along the chain, where their energy is dissipated as heat or converted to ATP energy – the power of the cell. The reduction of NADP + occurs as follows:

NADP + + 2e – + 2H + ®NADPH + H +

ATP PRODUCTION

It is at this stage that photosynthesis can be broken into cyclical and non-cyclical processes. We will focus on non-cyclical photosynthesis.

Non-cyclical photosynthesis is described by the following equation:

2 H 2 O + 2 NADP + + 3 ADP + 3 P i + light → 2 NADPH + 2 H + + 3 ATP + O 2

Each molecule of chlorophyll absorbs one photon of light. This excess of energy causes the photon to release an electron into Photosystem II, where it changes the P680 molecule to a P680*. This releases the electron, which is passed through various molecules in the electron transport chain. The electron transport chain causes a proton gradient across the chloroplast membrane. This gradient is used to produce ATP from ADP during photo phosphorylation.

After the reaching the plastocyanin, the electrons move into the P700 of the Photo system I, converting it to P700*. At this stage, the electrons are further excited by light energy absorbed by the Photo system I. The electrons travel further along the electron transfer chain, from the Photo system I to membrane-bound iron sulfur proteins to ferredoxin molecules, losing part of their energy to molecules of the ETC at each stage. This energy is used to further the proton gradient across the chloroplast membrane, and the electron reduces the NADP+ molecule to NADPH.

Systems seek to restore the equilibrium of concentrations, so by chemiosmosis, extraneous protons are forced back to the outer membrane of the thylakoid. The channel that the extraneous protons exit the membrane through is known as ATP synthase. This motion of protons rotates the ATP synthase protein and phosphorylates ADP to ATP.

In the diagram below, the transfer of an electron from excitation by a photon of light energy (far left) through Photo systems II and I, to the formation of ATP and NADPH is depicted. It should be noted that the electrons travel in one direction, while the NADPH and ATP produced are used in the furthering of the photosynthetic cycle.

Image Source: Wikimedia Commons

Figure 1: The movement of electrons along the electron transfer chain.

Losing electrons causes both photo systems to have a positive charge and become strong oxidizing agents, so they oxidize surrounding water molecules to obtain their electrons. This breaks the molecular bonds of water and dissociates it into its components, oxygen and hydrogen, which are released and used to form NADPH. This all occurs in the thylakoid membrane of the cell.

If you’re familiar with cellular respiration , you may be experiencing déjà-vu! Indeed, the process of ATP production is similar for both cellular respiration and photosynthesis . This AP® Biology photosynthesis review can also help bolster your understanding of cellular respiration.

KINETIC, POTENTIAL, AND THEN CHEMICAL ENERGY

We’ve discussed how water molecules are used to create the proton gradient, but this gradient is also created by regular diffusion. Some of the energy from electrons moving down the electron transport chain is converted to kinetic energy in order to bring in hydrogen ions released into the thylakoid membrane during the photolysis of water (remember, we discussed this at the start of the article).

Once in the inner space of the chloroplast, the kinetic energy of hydrogen is considered potential energy because of its position in the proton gradient. Potential energy can be considered as energy that is available to use for work.

We consider potential energy to be converted to the chemical energy in ATP bonds because it was usedto turn ADP into ATP by rotating ATP synthase.

LIGHT INDEPENDENT REACT®IONS

The released hydrogen protons are also used to reduce carbon dioxide into glucose in the second set of reactions in photosynthesis, called the Calvin cycle. This process also uses the ATP and NADPH’s stored energy to perform this reduction. The reaction is as follows:

3 CO 2 + 9 ATP + 6 NADPH + 6 H + → C 3 H 6 O 3 -phosphate + 9 ADP + 8 Pi + 6 NADP + + 3 H 2 O

Most plants can put three carbon dioxide molecules into an enzyme called ribulose bis-phosphate carboxylase (RuBisCo) to produce PGAL. ATP and NADPH are used to convert sugar back and forth from RuBisCo, but the final output is one PGAL. PGAL stores the energy for later conversion to sugars.

Therefore, the chemical energy that was carried by ATP and NADPH become stored in PGAL.

THE CALVIN CYCLE

The Calvin Cycle occurs in three main parts: fixation, reduction, and regeneration. During fixation, a RuBisCoenzyme catalyzes a reaction between 3 CO 2 molecules and three ribulose biphosphate (RuBP) molecules. This forms six molecules of 3-phosphoglyceric acid (3-PGA). The cycle completes three times, during each of which one RuBP and one CO 2 molecule interact. This is known as carbon fixation. During reduction, the ATP and NADPH created in the first stage of photosynthesis are used to convert the 3-PGA to glyceraldehyde 3-phosphate (PGAL). ATP is converted back to ADP in this reaction, and NADPH is converted back to NADP + . These products are recycled in the first phase of photosynthesis – the light-dependent phase. During regeneration, PGAL is exported to produce food products such as carbohydrates. This occurs in a 1:5 ratio: for every turn of the Calvin Cycle, two PGAL molecules are created. As it takes three turns of the cycles to use all RuBP molecules, six molecules of PGAL are created. One is exported, while five are used to regenerate RuBP. The one PGAL expelled collects in the cytosol. Once several have collected, PGAL molecules react to form sugar, in the form of six-carbon phosphates, which in turn react to form sucrose.

In the image below, the interaction between the light-dependent and light-independent reactions is shown. The products of the light reactions used in the Calvin Cycle can be seen, as are the products of the Calvin Cycle which are then reused in the light reactions.

Figure 2: The interaction between the light-dependent and -independent parts of photosynthesis.

After a long trip, the spare light energy settles down and is stored in PGAL!

When the plant needs energy to perform metabolic processes, sugars created by photosynthesis are broken down and the chemical energy is released, much in the same way as food is broken down for energy in animal cells. In this way, light energy (as well as a few other products – can you name them?) is used to create carbohydrates that can be stored and used as “food” energy.

We mentioned that there are similarities explored in photosynthesis and respiration. Can you name other aspects of cellular processes that are similar to those mentioned in this crash course of AP® Biology photosynthesis?

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Related Quizzes:

Cellular Respiration

Biochemistry

Quiz: Photosynthesis (AP Biology)

1. Which of the following occurs in the stroma of the chloroplast? light dependent reaction electron transport chain calvin cycle photolysis

2. The oxygen produced in photosynthesis comes from what molecule? glucose water P680 ATP

3. The photosynthetic process used by some plants to survive in a hot dry climate, like the desert? C4 Photosynthesis C3 Photosynthesis Noncyclic photophosphorylation Carbon fixation

4. Which of the following is NOT a produce of the light dependent reaction? Oxygen ATP NADPH Sugar

5. Which of the following i the source of the carbon in sugar produced during photosynthesis? carbon dioxide water rubisco ATP

6. Which of the following is the main difference between cyclic and noncyclic photophosphorylation? they use different electron acceptors Only photosystem I is used during the cyclic process noncyclic photophosphorylation occurs in the stroma noncyclic photophosphorylation does not produce ATP

7. Carbon fixation is catalyzed by what enzyme? P700 NADPH phosphoglycerate rubisco

8. The calvin cycle requires each of the following inputs EXCEPT: ATP NADPH O2 CO2

9. In the light dependent reactions, when light strikes the pigments (P700 or P680) what is the immediate result? excited electrons are passed to electron acceptors electrons are fused to form ATP glucose is produced carbon fixation occurs

10. In the calvin cycle, more ATP than NADPH is used, how is this difference made up? the cyclic pathway creates more ATP the calvin cycle occurs half as often as the light dependent reaction additional ATP is created from glucose excess NADPH is reused in the light reaction

Score = Correct answers:

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AP Biology : Photosynthesis

Study concepts, example questions & explanations for ap biology, all ap biology resources, example questions, example question #1 : photosynthesis.

Where does the Calvin Cycle take place?

Thylakoid membrane

Chloroplast outer membrane

Mitochondrial lumen

The Calvin Cycle (dark reactions) take place in the stroma of the chloroplasts, which is the aqueous space inside the organelle. 

Example Question #2 : Understand Light Independent Reactions (Calvin Cycle)

Where does the Calvin cycle take place in the chloroplasts?

Mitochondria

The Calvin cycle takes place in the stroma area in the chloroplasts. The mitochondria is another organelle, and the nucleus contains the DNA. The thylakoids are in the chloroplasts and contain the pigment chlorophyll in which the light reactions occur.

What is the name of the light-independent reaction of photosynthesis?

Krebs cycle

Beta-oxidation

Calvin cycle

The light-independent reaction in photosynthesis is called the Calvin cycle. Glycolysis and the Krebs cycle are the first and second steps in cellular respiration, respectively. Beta-oxidation is the process by which fatty acids are broken down into acetyl-CoA, which may enter the Krebs cycle, ultimately to produce ATP.

Which is not a step of the light independent reaction?

light absorption in photosystem II

carbon fixation

production of G3P

regeneration of RuBP

Absorption of sunlight in photosystem II is the first step of the light dependent reaction, not the light independent reaction. During the light independent reaction, or the Calvin Cycle, carbon fixation first occurs. CO2 produced during the light dependent reaction reacts with RuBP, ultimately producing PGA. This reaction is catalyzed by the enzyme Rubisco. Then, PGA is converted to G3P, using ATP and NADPH produced during the light dependent reaction. The G3P is ultimately converted to glucose. Every 3 cycles of the Calvin Cycle (light independent reaction), 6 molecules of G3P are produced; only 1 is used to produce glucose. The remaining 5 molecules of G3P are used to regenerate RuBP to allow the Calvin Cycle to continue.

Where do light independent reactions of photosynthesis occur?

stroma of chloroplasts

thylakoid of chloroplasts

Light independent reactions occur in the stroma of the chloroplasts. Light dependent reactions occur in the thylakoid membrane.

What the products of the light independent reactions?

O2, NADP+, ATP

glucose, NADP+, H2O

glucose, NADPH, H2O

CO2, NADPH, ATP

Example Question #2 : Photosynthesis

The products of the light independent reaction are glucose, NADP+, and H2O. The reactants are CO2, NADPH, and ATP.

Example Question #91 : Plant Biology

Which enzyme is important in photosynthesis, and what is its function?

ribulose bisphosphate carboxylase; carbon fixation during the first step of light independent reaction

amylase; carbon fixation during the first step of light independent reaction

ribulose bisphosphate carboxylase; captures energy from the sun during light dependent reaction

oxidase; captures energy from the sun during light dependent reaction

During the first step of the light independent reaction, or Calvin Cycle, CO2 produced from the light dependent reaction reacts with RuBP. This reaction is catalyzed by Rubisco, or ribulose bisphosphate carboxylase.

Which is not a required input for the Calvin Cycle?

The Calvin Cycle, or light independent reaction, does not utilize sunlight as an input. During the light independent reaction, or the Calvin Cycle, carbon fixation first occurs. CO2 produced during the light dependent reaction reacts with RuBP, ultimately producing PGA. This reaction is catalyzed by the enzyme Rubisco. Then, PGA is converted to G3P, using ATP and NADPH produced during the light dependent reaction to allow this reaction to occur. The G3P is ultimately converted to glucose. Every 3 cycles of the Calvin Cycle (light independent reaction), 6 molecules of G3P are produced; only 1 is used to produce glucose. The remaining 5 molecules of G3P are used to regenerate RuBP to allow the Calvin Cycle to continue.

Example Question #2221 : Ap Biology

How many G3P molecules are produced after 3 cycles of the Calvin Cycle; and how many of these G3P molecules are used to produce glucose after 3 cycles of the Calvin Cycle?

Every 3 cycles of the Calvin Cycle (light independent reaction), 6 molecules of G3P are produced; only 1 is used to produce glucose. The remaining 5 molecules of G3P are used to regenerate RuBP to allow the Calvin Cycle to continue.

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