Double membrane (inner & outer) 3-6 um, lens shaped. Photosynthesis.

Double membrane (inner & outer) 3-6 um, lens shaped. Photosynthesis.

• A. Chloroplast
• B. Nucleus
• C. Endoplasmic Reticulum
• D. Peroxisome

Answer: (A)

Chloroplasts are the organs where photosynthesis happens in plant cells. They are enclosed by a double membrane and are about 3–6 micrometers in diameter with a lens-shaped, oval form. Inside, their membranes form stacks of thylakoids (grana) where the light-dependent reactions occur, and the surrounding fluid-filled stroma where the Calvin cycle takes place. This double-membrane setup helps create distinct compartments for different steps of photosynthesis, efficiently capturing light energy and converting it into chemical energy. The nucleus also has a double membrane, but it is much larger and houses genetic material, not the site of photosynthesis. The endoplasmic reticulum is a network of membranes involved in manufacturing and transport of molecules, not a discrete double-membrane organelle specialized for photosynthesis. Peroxisomes are single-membrane-bound compartments involved in metabolism and detoxification, and they do not carry out photosynthesis.

Chloroplasts are the organs where photosynthesis happens in plant cells. They are enclosed by a double membrane and are about 3–6 micrometers in diameter with a lens-shaped, oval form. Inside, their membranes form stacks of thylakoids (grana) where the light-dependent reactions occur, and the surrounding fluid-filled stroma where the Calvin cycle takes place. This double-membrane setup helps create distinct compartments for different steps of photosynthesis, efficiently capturing light energy and converting it into chemical energy.

The nucleus also has a double membrane, but it is much larger and houses genetic material, not the site of photosynthesis. The endoplasmic reticulum is a network of membranes involved in manufacturing and transport of molecules, not a discrete double-membrane organelle specialized for photosynthesis. Peroxisomes are single-membrane-bound compartments involved in metabolism and detoxification, and they do not carry out photosynthesis.