DENDROLOGY

Detailed explanation-1: -In particular, their three membranes divide chloroplasts into three distinct internal compartments: (1) the intermembrane space between the two membranes of the chloroplast envelope; (2) the stroma, which lies inside the envelope but outside the thylakoid membrane; and (3) the thylakoid lumen.

Detailed explanation-2: -Like mitochondria, chloroplasts are surrounded by two membranes. The outer membrane is permeable to small organic molecules, whereas the inner membrane is less permeable and studded with transport proteins.

Detailed explanation-3: -They have an outer and inner membrane enveloping the intermembrane space. The inner membrane separates ‘stroma’ from the intermembrane space. The presence of a double-membrane helps in creating a concentration gradient and controls the flow of substances across it.

Detailed explanation-4: -The chloroplast envelope consists of a pair of lipid bilayer membranes. They form the interface between the stromal space of the chloroplast and the cytoplasm of the cell. The existence of two envelope membranes is not unique to chloroplasts but is common to all types of plastids in higher plants.