PHOTOSYNTHESIS

What substances are the reactants in photosynthesis? Include the name and chemical formula of each substance in your answer.

Carbon dioxide (CO2), water (H2O),

What substances are produced during photosynthesis? Include the name and chemical formula of each substance in your answer.

Oxygen (O2), Water (H2O), Glucose (C6H12O6)

In what part of the chloroplast do the light-independent reactions occur?

The light-independent reactions occur in the Stroma.

What molecule(s) are "regenerated" in this phase of the cycle?

3 RuBP molecules are "regenerated" in this phase of the cycle

Identify the types and numbers of molecules that provide the free energy necessary for the reduction of the PGA molecules.

6 ATP molecules as well as 6 NADPH molecules are provided as the free energy necessary for the reduction of the PGA molecules.

Is carbon dioxide involved in the light-dependent reaction?

Carbon dioxide is not involved in a light-dependent reaction.

Name the embedded protein complex found in the thylakoid membrane that provides excited electrons to the electron transport chain.

Photosystem II

According to Model 2, what is the source of replacement electrons for those released from photosystem II?

The source of replacement electrons for those released from photosystem 2 are electrons from the split of water.

According to Model 3, what are the three phases of the Calvin cycle?

The three phases of the Calvin cycle are Carbon Fixation, Reduction, and Regeneration.

How many carbon atoms are in each PGA molecule?

3 carbon atoms are in each PGA molecule

How many PGA molecules are made in one turn of the Calvin cycle?

Six PGA molecules are made in one turn of the Calvin Cycle

Considering your answers to Question 4, what compound is best able to absorb the light energy from the Sun and convert it into chemical energy?

The thylakoid, and the chlorophyll in the thylakoid, would best be able to absorb the light energy from the sun and convert it into chemical energy because the thylakoid specializes in light-dependent reactions

Explain what happened to the carbon atoms from the carbon dioxide molecules that entered the Calvin cycle.

The carbon atoms from the carbon dioxide molecules that entered the Calvin cycle underwent Carbon Fixation, to be transformed into Phosphoglycerate (PGA) molecules

How many RuBP molecules are used in one turn of the Calvin cycle?

Three RuBP molecules are used in one turn of the Calvin Cycle

Calculate the total number of carbon atoms represented in all of the RuBP molecules used in one turn of the Calvin cycle.

15 carbon atoms (5 Carbon atoms x 3 RuBP molecules)

Write a chemical reaction that summarizes all of the chemical reactions in the light-dependent reactions of photosynthesis starting with two water molecules.

2H2O + NADP+ + ADP → NADH + ATP + O2

Name the embedded protein complex found in the thylakoid membrane that uses excited electrons to reduce NADP+ into NADPH.

Photosystem I

In what part of the chloroplast do the light-dependent reactions occur?

The light-dependent reactions occur in the thylakoid membrane

What molecule does the PGA molecule turn into during this phase of the Calvin cycle?

During the reduction phase of the Calvin cycle, the PGA molecule turns into a PGAL molecule (phosphoglyceraldehyde)

How many water molecules are produced in the reduction phase of the Calvin cycle?

Six water molecules are produced by the reduction phase of the Calvin cycle

What is the energy source for photosynthesis?

Sunlight (electromagnetic energy) is the energy source for photosynthesis

Identify the types and numbers of molecules that provide the free energy necessary for the regeneration of the high energy molecules of the Calvin cycle

3 ATP molecules provide the free energy necessary for the regeneration of the molecules in the regeneration phase of the Calvin cycle.

Name the embedded protein complex found in the thylakoid membrane that converts ADP to ATP using free energy from a flow of hydrogen ions.

ATP Synthase

In the photosynthesis reaction in Model 1, twelve water molecules are shown as reactants, but six water molecules are shown as products. Are any of the twelve water molecules products of the light-dependent reactions?

No, water is not a product of the light-dependent reactions

What is another name for the light-independent reactions?

Light-independent reactions are also called the Calvin cycle

The structures inside the organelle in Model 1 are called thylakoids. What compound necessary for photosynthesis is contained in the thylakoids?

Chlorophyll is necessary b/c it absorbs light

According to Model 2, what is the source of replacement electrons for those released from photosystem I?

Electrons travel from the electron transport chain (from Photosystem II) to replace those released from Photosystem I

Why is it necessary to have six CO2 entering the chloroplast?

It is necessary to have six CO2 entering the chloroplast because they will interact with the 12 hydrogen atoms and six of the oxygen atoms from the 12 H2O molecules to form one glucose molecule. A glucose molecule has a chemical structure of C6H12O6, so six carbon atoms, and thus six CO2 molecules, are needed.

What happens to the PGAL molecule that does not continue on in the Calvin cycle?

The PGAL molecule that does not continue on in the Calvin cycle is used by the cell to produce glucose and other biomolecules

Is the total number of carbon atoms present in the Calvin cycle changed during the reduction phase? Support your answer with evidence from Model 3.

The total number of carbon atoms present in the Calvin cycle is not changed during the reduction phase, because at the beginning of the reduction phase, there are 6 PGA molecules, each with 3 carbon atoms, for a total of 18 carbon atoms, and at the end of the reduction phase, there are 6 PGAL molecules, each with 3 carbon atoms, for a total of 18 carbon atoms. Thus, although the molecule present at the beginning of the reduction phase differs from that which is present at the end of the reduction phase, the number of carbon atoms remains unchanged.

How many carbon atoms are in each RuBP molecule?

There are 5 carbon atoms in each RuBP molecule.

Calculate the total number of oxygen, NADPH, and ATP molecules that are produced when twelve water molecules complete the light-dependent reactions.

12 H2O molecules = 6O2, 6NADH, and 6ATP

Where in the organelle are these molecules (reactants for photosynthesis) stored before they are used in photosynthesis?

Before being used in photosynthesis, carbon dioxide and water are both stored in the stroma, while sunlight energy is stored in the thylakoids.

Where do the ATP and NADPH produced during the light-dependent reactions go when the process is complete?

The ATP and NADPH go to the stroma after the light-dependent reactions are completed. The stroma is where the Calvin cycle is located.

Is photosynthesis an endergonic or exergonic reaction?

Endergonic (energy is a reactant, not a product)

The light-dependent reactions include an electron transport chain system that works in a very similar fashion to the electron transport chain in respiration. Briefly describe how this system works and what job it performs in the light-dependent reactions. (Your answer should include a discussion about concentration gradient.)

Light-dependent reactions include an electron transport chain system, one that works in a very similar fashion to the electron transport chain in respiration, because they provide energy to pump protons (H+) into the inner thylakoid and create a proton gradient. This allows protons to flow out of the thylakoid and power ATP production. It is important that the excited electrons move through the electron transport chain in order to provide the free energy needed to pump hydrogen ions into the inner thylakoid.

Consider the term "carbon fixation." Think individually for a moment what this term might mean, then share ideas among the group. Record the group's consensus definition for carbon fixation here.

One definition for "fixation" is "the action of making something firm or stable," so I think that "carbon fixation" could involve taking the carbon atoms from the incoming CO2 molecules and fixing them into another compound/molecule, which in this case would be Phosphoglycerate (PGA)

Explain where the hydrogen and oxygen atoms in these water molecules (that are produced in the reduction phase of the Calvin cycle) originated.

The hydrogen and oxygen atoms in these water molecules originated from the 6 PGA molecules that are present at the beginning of the reduction phase

Calculate the total number of carbon atoms represented in all of the PGA molecules used in one turn of the Calvin cycle.

There are 18 carbon atoms in all of the PGA molecules used in one turn of the Calvin cycle.

How many CO2 molecules are used in one turn of the Calvin cycle?

There are three carbon dioxide molecules that are used in one turn of the Calvin cycle.

How many total carbon atoms leave the Calvin cycle before the regeneration phase?

Three total carbon atoms leave the Calvin cycle before the regeneration phase.