VCE Biology - Unit 3, AoS2

Photosynthesis

The process of capturing light energy to power the production of glucose and oxygen from carbon dioxide and water.

Mesophyll cell

A plant cell type found in leaves that contain large amounts of chloroplasts.

Chloroplast

A membrane-bound organelle only found in plant and photoautotroph cells that is the site of photosynthesis.

Stomata

A small pore on the leaf’s surface that opens and closes to regulate gas exchange.

Light-dependent stage

The first stage of photosynthesis, where light energy splits water molecules into oxygen and hydrogen inside the thylakoid membranes.

Thylakoid

A flattened sac-like structure housed inside the chloroplast. Each thylakoid is made up of a chlorophyll-containing membrane enclosing a lumen. Thylakoids are the location of the light-dependent stage of photosynthesis.

Granum

A stack of thylakoids.

NADPH

A coenzyme that is a proton (H+) and electron carrier in photosynthesis.

ATP

Adenosine triphosphate, a high energy molecule that, when broken down, provides energy for cellcular processes.

Light-independent stage / Calvin Cycle

The second stage of photosynthesis where carbon dioxide is used to form glucose in the stroma of a chloroplast.

Stroma

The fluid substance that makes up the interior of chloroplasts. It is the site of the light-independent stage of photosynthesis.

Inputs of light-dependent stage

H2O (water), NADP+ (uncharged NADPH), and ADP + Pi (uncharged ATP)

Outputs of light-dependent stage

O2 (oxygen), NADPH, and ATP.

Inputs of light-independent stage

CO2 (Carbon dioxide), NADPH, and ATP

Outputs of light-independent stage

C6H12O6 (glucose), NADP+ (uncharged NADPH), ADP + Pi (uncharged ATP), and H2O (water)

Rubisco

A pivotal enzyme involved in initial carbon fixation during the light-independent stage of photosynthesis.

Carbon fixation

The process in living organisms where inorganic carbon, typically within carbon dioxide, is converted into organic compounds such as glucose. Carbon fixation is a central part of the light-independent stage of photosynthesis.

Inorganic

A compound that does not contain a carbon-hydrogen bond

Organic

A compound containing a carbon-hydrogen bond

Photorespiration

A wasteful process in plants initiated by Rubisco that limits photosynthesis.

C3 plants

Plants with no evolved adaptation to minimise photorespiration.

C4 plants

Plants that minimise photorespiration by separating initial carbon fixation and the remainder of the Calvin cycle over space.

Bundle-sheath cell

A plant cell type that is the site of most of the Calvin cycle in C4 plants.

CAM plants

Plants that minimise photorespiration by separating initial carbon fixation and the remainder of the Calvin cycle over time.

Difference between C3 and C4 plants

Cells that calvin cycle occurs in

Difference between C3 and CAM plants

Time (calvin cycle occurs at night)

Light intensity on photosynthesis

Rate increases until it plateaus

Increases temperature, leading to denaturation if too hot.

Temperature on photosynthesis

Rate increases until above optimal temperature, where it denatures and can’t function.

pH levels on photosynthesis

Functions fastest at optimal pH level, then denatures below or above.

Carbon dioxide concentration on photosynthesos

Rate increase until it plateaus

Lack of water on photosynthesis

Photorespiration is more likely to occur, decreasing rate.

Competitive reversible inhibitor on photosynthesis

Increases slower than usual, until plateus

Non-competitive and/or irreversible inhibitor on photosynthesis

Increases as normal, but plateaus at a rate slower than usual.