AP BIOLOGY

Detailed explanation-1: -Inside a chloroplast, thylakoid has two structural forms. One is stroma thylakoid (stroma lamellae), which is a membrane-bound structure embedded into the stroma of chloroplast. The other is granum, which is a well-packed stack of thylakoids (see Figure 1).

Detailed explanation-2: -What is stroma in a chloroplast? Stroma is the fluid-filled internal space of the chloroplasts which encircle the grana and the thylakoids. It contains chloroplast DNA, starch and ribosomes along with enzymes needed for the Calvin cycle.

Detailed explanation-3: -The green pigment chlorophyll is located within the thylakoid membrane, and the space between the thylakoid and the chloroplast membranes is called the stroma (Figure 3, Figure 4).

Detailed explanation-4: -The space between the inner membrane and the thylakoid membrane is filled with stroma, a matrix containing dissolved enzymes, starch granules, and copies of the chloroplast genome.