Chapter 4 section questions
What are the stages of photosynthesis? Which stage occurs first?
Light-dependent reactions and the Calvin Cycle. The Light Reactions. The first stage of photosynthesis is called the light reactions. During this stage, light is absorbed and transformed to chemical energy in the bonds of NADPH and ATP.
What happens during the carbon fixation step of the Calvin cycle?
The Calvin Cycle, of which carbon fixation is the first step, also occurs as part of the LIR and takes place in the stroma. ATP, CO2, NADPH, and H2O are all utilized in the LIR. Three molecules of carbon dioxide are required for a full Calvin Cycle.
During which stage of photosynthesis is glucose made?
The Calvin cycle takes over where the light reactions end. It uses chemical energy stored in ATP and NADPH (from the light reactions) and carbon dioxide from the air to produce glucose, the molecule that virtually all organisms use for food.
Explain what might happen if the third step of the Calvin cycle did not occur.
The cycle would not be able to start again without the five carbon compound therefore no glucose would be made.
Explain the role of the first electron transport chain in the formation of ATP during the light reactions of photosynthesis.
The electron transport chain moves from down the chain of transport molecules. While this is happening their energy is captured and used to pump more hydrogen ions.
Summarize what happens during the light reactions of photosynthesis
The light-dependent reactions use energy from sunlight to produce oxygen and con- vert ADP and NADP+ into the energy carri- ers ATP and NADPH. ... NADP+ molecules pick up the high-energy electrons along with H+ ions to become NADPH.
Plants release oxygen during the day but not during the night. Explain why.
They do not release oxygen at night because there is no sunlight. The sunlight is a key component in photosynthesis. Without sunlight photosynthesis would not happen. Oxygen is a product of photosynthesis. So if photosynthesis does not happen no oxygen is released.
The first living things appeared on Earth at least a billion years before photosynthetic organisms appeared. How might the earliest organisms have obtained energy before photosynthesis evolved? What process could they have used to make food?
chemosynthesis
Describe the chloroplast and its role in photosynthesis.
green pigment in a chloroplast that absorbs light for photosynthesis. groups of molecules, pigments, that include chlorophyll and it is found in the thylakoid membrane. ... Light energy is captured from sunlight and then turned into chemical energy. The chemical energy is then stored in ATP and NADPH.
