Photosynthesis Review Quiz

Where do the light dependent reactions of photosynthesis take place?

• In the stroma

• In the outer membrane of the chloroplast

• In the thylakoids

• In the inner membrane of the chloroplast

Answer explanation

The light dependent reactions take place in the thylakoid disks. Remember my trick: "THYlakoids, LIGHT reactions"

Which of the following is NOT a reactant in the light dependent reactions?

• H₂O

• CO₂

• Light

Answer explanation

CO₂ is a reactant in the light independent reactions.

What product is released from the cell as a result of the light dependent reactions?

• H₂O

• ATP

• NADPH

• O₂

Answer explanation

Water is a reactant for the light dependent reactions. ATP and NADPH are products of the light dependent reactions, but they are not released, they go on to get used in the Calvin cycle. Oxygen gas (O₂) is released from the splitting of water.

What is the role of NADPH in photosynthesis?

• It is an electron carrier.

• It provides the cell with energy when it is hydrolyzed.

• It is a product of the Calvin cycle.

• It is a reactant in the light dependent reactions.

Answer explanation

NADPH is an electron carrier and carries electrons from the light dependent reaction to the Calvin Cycle. It is a reactant in the light dependent reactions and a product of the Calvin cycle.

What causes the release of oxygen (O₂) in the light dependent reactions?

• The creation of ATP

• The splitting of water by the light

• The NADPH carrying electrons

• CO₂ joining with 6 carbon molecules.

Answer explanation

The energy from the light hitting Photosystem II (PS II) causes the water molecule to split apart and create oxygen.

After H₂O is split in the light dependent reactions, what does the H⁺ get used for?

• To make CO₂

• To make glucose

• To make ATP

• To make O₂

Answer explanation

Remember in the story, Haley makes an Apple, Tomato and Pineapple smoothie? This is to represent the H⁺ which gets used to make ATP.

What causes ATP to release energy?

• ATP just is energy.

• ATP is hydrolyzed (water is added) and ATP becomes ADP, releasing energy

• ATP releases energy when it reacts with NADPH.

• ADP releases energy when it is converted to ATP.

Answer explanation

ATP itself is not energy. Rather, we get energy from ATP when it is hydrolyzed. This means water is added and causes ATP to split apart into ADP + an inorganic phosphate. When this happens, a lot of energy is released, and that is the energy we speak of when we talk about ATP!

Which of the following is a reactant in the Calvin cycle?

• Light

• H₂O

• Glucose

• CO₂

Answer explanation

Light and Water are reactants in the light dependent reactions (step 1).

Glucose is a product of the Calvin cycle.

In the first step of the Calvin cycle, 6 CO₂ molecules combine with 6 other carbon molecules to form what?

• Glucose

• G3P

• ATP

• 12 3-PGA molecules

Answer explanation

In the first step of the Calvin Cycle, 6 CO₂ molecules (the 6 guys from Colorado) combine with 6 carbon molecules (6 ladies) to form 12 3-PGA molecules. I remember this because 6 + 6= 12, and that's why they form 12 3-PGA molecules. It's just a different arrangement of carbon.

In the second step of the Calvin cycle, the ATP becomes ADP and the NADPH becomes NADP⁺, and these two reactions ultimately produce what molecule?

• Glucose

• G3P

• Oxygen

• Water

Answer explanation

This is the part of the story where Haley has her "ADrenaline Party" and writes a review for Never A Dull Party Hall (NADP is A Plus!). Then they send the Guys with 3 Pizzas to thank her.