Photosynthesis

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.

• The concentration of dissolved oxygen in the flask with algae will always be higher.
• The concentration of dissolved oxygen in the flask with algae will always be lower.
• The concentration of dissolved oxygen in the flask with algae will be higher in the light but lower in the dark.
• The concentration of dissolved oxygen in the flask with algae will be lower in the light but higher in the dark.

Tags

NGSS.HS-LS2-5

NGSS.HS-LS1-5

If plants are grown with H₂O containing a radioactive isotope of oxygen (¹⁸O), subsequent analysis will show that ¹⁸O first appears in which of the following molecules produced by the plants?

• O₂

• glyceraldehyde 3-phosphate (G3P)
• CO₂

• ribulose bisphosphate (RuBP)

Tags

NGSS.HS-LS1-5

Which of the following statements about the location of photosynthesis reactions is correct?

• The light reactions happen on the thylakoid membranes and the Calvin cycle happens in the stroma.
• The light reactions and the Calvin cycle both occur inside the thylakoids.
• The light reactions and Calvin cycle both occur in the stroma of the chloroplast
• The Calvin cycle happens on the thylakoid membranes and the light reactions happen in the stroma.

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

• The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP + Pi, and NADP+ to the light reactions.
• The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the Calvin cycle provides water and electrons to the light reactions.
• The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP.
• The light reactions provide the Calvin cycle with oxygen for carbon fixation, and the Calvin cycle provides the light reactions with sugars to produce ATP.

Tags

NGSS.HS-LS2-5

NGSS.HS-LS1-5

Which of the following molecules are BOTH products of the light reactions of photosynthesis AND are needed to run the Calvin cycle?

• CO2 and glucose
• H2O and O2
• ATP and NADPH
• ADP + Pi, and NADP+

Which of the following is the final product of the electrochemical gradient formed across the thylakoid membrane during the light reactions of photosynthesis?

• ATP
• ADP + Pi
• NADP+
• H2O

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. During the daytime, the pH inside the thylakoid is much lower than the pH in the stroma or cytosol. Given what you know about the light reactions, what would you expect to happen at night regarding pH?

• The pH within the thylakoid space will stay much lower than the stroma and cytosol.
• The pH within the thylakoid space will go even lower than during the daytime.
• The pH within the thylakoid space will increase until it is equal to the stroma and cytosol.
• The pH of the stroma will decrease until it is much lower than in the thylakoid space.

Tags

NGSS.HS-LS1-5

Photosystem II is often considered the strongest biological oxidizing agent. Given its function, why is this necessary?

• It is the receptor for the most excited electrons in either photosystem.
• It transfers electrons to the photosynthetic electron transport chain.
• It transfers its electrons directly to NADP+ to produce NADPH.
• It obtains electrons from the oxygen atom in a water molecule, so it must have a greater affinity for electrons than oxygen has.

Which of the following is a function of the Calvin cycle? Select all that apply.

• Recycle ADP and Pi for the light reactions from ATP
• Produce simple sugars (G3P) from CO2
• Recycle the NADP+ needed by the light reactions
• Make ATP from ADP + Pi
• Make the NADPH needed for the light reactions

Tags

NGSS.HS-LS2-5

In the Calvin cycle, an early step in the process of carbon fixation combines three molecules of CO2 with three molecules of RuBP to produce three 6-carbon molecules, which are immediately converted to six 3-carbon molecules. These six molecules are phosphorylated and reduced to produce glyceraldehyde 3-phosphate (G3P). What additional events occur to complete the Calvin cycle?

• release of two G3P to make sugars and regeneration of ATP from ADP
• release of one G3P to make sugars and regeneration of RuBP
• release of one G3P to make sugars and regeneration of NADPH from NADP+
• release of one G3P to make sugars and regeneration of CO2

Tags

NGSS.HS-LS2-5

NGSS.HS-LS1-6