U3L5 Photosynthetic Reactions AP Bio

Multiple Choice

Which of the following is an important difference between the light-dependent and the light-independent reactions of photosynthesis?

• The light-dependent reactions occur only during the day, whereas the light-independent reactions occur only during the night.

• The light-dependent reactions produce ATP and NADPH, whereas the light-independent reactions use energy stored in ATP and NADPH.

• The light-dependent reactions occur in the cytoplasm of the cell, whereas the light-independent reactions occur in chloroplasts.

• The light-dependent reactions utilize carbon dioxide and water, whereas the light-independent reactions produce carbon dioxide and water.

Multiple Choice

Which of the following best describes the processes that take place within the Calvin cycle?

• ATP is used in the production of a three-carbon sugar.

• 
  Chlorophyll captures light.

• NADP+ is reduced into NADPH.

• ATP is produced during the reduction phase.

Multiple Choice

The light-dependent reactions are described as a series of chemical reactions beginning with photons striking a pigment molecule.

Which of the following correctly describes the pathway of electrons through the light-dependent reactions?

• Water → Photosystem I → Photosystem II → Electron Transport Chain → NADPH

• Water → Photosystem I → Electron Transport Chain → Photosystem II → NADPH

• Water → Photosystem II → Electron Transport Chain → Photosystem I → NADPH

• Water → Photosystem II → Photosystem I → Electron Transport Chain → NADPH

Multiple Choice

Radioisotopic labeling is a technique for tracking the passage of a sample of a substance through a reaction, a metabolic pathway, or a cell. A researcher labeled water with the radioactive isotope oxygen-18. The researcher then exposed a plant specimen to the radioactive labeled water, and the plant underwent photosynthesis. The researcher tested the oxygen gas released from the photosynthetic process and noted that it is also labeled with oxygen-18. 

Which of the following is the best explanation?

• During the light-dependent reactions, water was split. The hydrogen atoms reacted with the carbon dioxide, releasing oxygen gas as a waste product.

• During the light-dependent reactions, water was split. Oxygen gas was released as a waste product, so that the protons and electrons could be used during photosynthesis.

• During the light-independent reactions, water is split, producing NADPH. Oxygen gas was released.

• During the light-independent reactions, oxygen is used to produce carbohydrates. Hydrogen gas was released as a waste product.