AP BIO UNIT 3.WORKSHEETS

Vocabulary terms covering leaf stomatal function, light-dependent chemiosmosis and electron transport, and overall photosynthetic structures and reactions.

Stomata

Small pores that serve as the principal means of gas exchange in vascular plants, opening to allow $CO_2$ to enter and water and oxygen to escape.

Guard cells

A pair of banana-shaped cells that control the opening and closing of leaf stomata.

Stomata density

The number of stomata per unit area of a leaf.

Desiccation

Drying out caused by excessive evaporation, particularly when water is unavailable under drought conditions.

Photolysis

The reaction where $H_2O$ splits into electrons, $2H^+$, and oxygen, which immediately bonds with another oxygen atom to make $O_2$.

Electron transport chain (ETC)

A pathway that allows electrons to flow from photosystem II to photosystem I.

Proton pump

A transport mechanism that uses energy from electron transport to move $H^+$ against its gradient from the stroma into the thylakoid lumen.

NADP+ Reductase

An enzyme that reduces $NADP^+$ by adding electrons to form NADPH, which is then sent to the Calvin Cycle.

ATP Synthase

An enzyme that couples the diffusion of $H^+$ to produce ATP from ADP and inorganic phosphate.

Photosynthesis

The process performed by plants, algae, and some bacteria that transforms light energy from the sun into chemical energy stored in glucose.

Glucose

A simple sugar produced by photosynthesis that stores chemical energy which cells transfer to ATP for cellular processes.

Chloroplast

The organelle in which photosynthesis occurs, composed of thylakoid membrane structures and stroma.

Thylakoids

Flat membrane sacs located inside the chloroplast.

Grana

Stacks of thylakoids found inside the chloroplast.

Stroma

The fluid-filled space surrounding the thylakoids within the chloroplast.

Chlorophyll

A green pigment located inside the thylakoid membrane that absorbs light energy from the sun to power photosynthesis.

Light-dependent Reaction

The stage of photosynthesis that takes in light energy and directly requires light.

Light-independent Reaction (Calvin Cycle)

The stage of photosynthesis that produces glucose and does not directly require light.