Photosynthesis - AP Biology

The photosynthesis equation can be written as:

From this equation, we can see that plants take in carbon dioxide, water, and light energy as reactants and produce glucose and oxygen as products.

Autotrophs are organisms that produce complex organic compounds from substances present in the surroundings. These organisms may do this through the use of energy from light or from inorganic chemical reactions.

In contrast, heterotrophs require organic input in order to generate biological compounds and are unable to use light or inorganic materials for energy.

Photosynthesis occurs in the chloroplasts of plant cells, where carbon dioxide is reduced and water is oxidized to create sugar. During this process electrons demonstrate increased potential energy as they move from water to sugar. The process requires an initial energy input, derived from photons.

Plants are considered photoautotrophs, meaning that they can use the electromagnetic energy from sunlight to generate organic chemical energy. The process for this conversion is photosynthesis, which takes place in the chloroplasts of the plant cells. Sunlight excites electrons, which donate energy to form NADH and ATP. These compounds enter the Calvin cycle, which converts carbon dioxide to glyceraldehyde-3-phosphate, a sugar that can easily be converted to glucose and used for energy.

The sugars produced from photosynthesis then undergo oxidation via cellular respiration in order to actually produce ATP. Remember that plant cells contain both chloroplasts (to make sugars) and mitochondria (to make ATP).

Autotrophs create organic material from inorganic materials. Autotrophs are self-feeders in that they do not consume other organic materials but rather create their own organic materials. Plants and other photosynthetic organisms are examples of autotrophs.

Plants are an example of autotrophs. Autotrophs sustain themselves without consuming other organic material. Instead they create organic material from inorganic materials.

The leaves are the major sites of photosynthesis in most plants. The chloroplasts are located in the mesophyll—interior tissues of the leaves—and are the primary sites of photosynthesis.

The correct answer is two major stages. The first stage is known as the light reactions where solar energy is converted to chemical energy. The second stage is the Calvin cycle that synthesizes sugar.

CAM plants open their stomata only at night, when temperatures are lower and water loss is less severe. This prevents gas exchange during the day thus making them less efficient at photosynthesis, but the water conservation makes it a worthwhile trade off. The processes of glycolysis, oxidative phosphorylation, the Calvin cycle and the Krebs cycle occur in all plants.

Glucose is the six carbon sugar that is the main product of photosynthesis. Water and carbon dioxide are the reactants in photosynthesis. Lipids are fat molecules that store energy in cells.

Photosynthesis begins with energy from light being converted to chemical energy. The only answer explanation accurately explaining this process describes the conversion of light energy (photons) to chemical energy (excited electrons).

Photons present in light strike and excite electrons in chlorophyll.

The photons are highly energized light particles, which strike chlorophyll and excite and free electrons in the chlorophyll molecule. These excited electrons pass through the electron transport chain and their energy is collected to make ATP.

The light reactions are the steps of the photosynthesis that function to convert solar energy into chemical energy that can be used during the Calvin cycle. The light reactions use solar energy to reduce to and to convert to .

During the light reactions water is split and the by-product is oxygen. Oxygen is then released back into the atmosphere. Sugars are produced during the Calvin cycle and are not a direct product of the light reactions.

The light reactions of photosynthesis occur in the thylakoid membranes inside of chloroplasts in plant cells. Photosynthesis depends on the buildup of a proton gradient across a membrane to generate ATP. The thylakoid is an organelle present only in plants. The phospholipid bilayer and cell wall surround plant cells, and are not involved in photosynthesis.

The molecule is reduced because when a molecule gains an electron, it is said to be reduced. The answer oxidized would have been chosen if the molecule lost an electron. Plasmolysis has nothing to do with the gain or loss of an electron, and the term redoxed does not fit into this question. Hydrolysis is when a bond is broken using water, so that is incorrect as well.

The light dependent reaction converts solar energy to chemical energy, using the photosystem to capture light energy, and ultimately produce ATP and NADPH. Pigment molecules in the photosystem absorb photons of light, which then reach the chlorophyll, exciting electrons in the chlorophyll. The excited electron then is transferred to a primary electron acceptor of the electron transport chain (and is replaced by the splitting of water (to produce O2, H+ and e-)).

The ATP synthase protein is embedded in the thylakoid membrane. When sunlight is captured by photosystem II in the light dependent reaction, water is split, producing O2 and 2 H+ ions and 2 electrons. As the electrons flow down the electron transport chain, this energy is used to pump hydrogen ions from the stroma into the thylakoid space, producing a high concentration of hydrogen ions inside the thylakoid lumen. Eventually, the hydrogen ions then flow from the area of high concentration (in the thylakoid lumen) to an area of low concentration (in the stroma ), through the ATP synthase protein. The movement of the hydrogen ions through this structure combines ADP with phosphate, producing ATP.

ATP and NADPH are produced during the light dependent reaction, and are reactants necessary for the light independent reaction (Calvin Cycle) to occur. During the light independent reaction, ATP and NADPH are used to convert phosphoglycerate molecules (PGA) to glyceraldehyde-3-phosphate molecules (G3P). G3P is then used to produce glucose.

Light dependent reactions convert solar energy to chemical energy (in the form of ATP and NADPH). Sunlight and H2O are the reactant of the light dependent reaction. The sunlight is captured by photosystem II, and is used to excite electrons. Splitting of H2O produces hydrogen ions used to establish the proton gradient, and electrons produced replace the electrons transferred to the primary electron acceptor.