Although all green plant parts have chloroplasts, leaves are the major organs of photosynthesis in most plants. Chlorophyll is the green pigment in chloroplasts that gives a leaf its color and that absorbs the light energy used to drive photosynthesis.
Chloroplasts are primarily in cells of mesophyll , green tissue in the leaf's interior.
CO 2 enters and O 2 exits the leaf through microscopic pores called stomata . Water absorbed by the roots is transported to leaves through veins or vascular bundles which also export sugar from leaves to nonphotosynthetic parts of the plant. The chloroplast is bound by a double membrane which partitions its contents from the cytosol. A narrow intermembrane space separates the two membranes. Thylakoid Space .