Why do plants such as maize and sugarcane have dimorphic chloroplasts. Explain photosynthetic carbon cycle in such plants?

Explanation

Maize and sugarcane have dimorphic chloroplasts. They have `C_(4)` or Hatch and slack pathway for carbon di oxide fixation.
Dimorphic chloroplast: Bundle sheath chloroplast are larger and thylakoids are not arranged in granum. Mesophyll chloroplast are smaller and thylakoilds are arranged in granum.
1 `C_(4)` pathway is completed in two phases , first phase take place in stroma of mesophyll cells , where the `CO_(2)` acceptor molecule is 3-Carbon compound , Phospho Enol Pyruvate (PEP) to form 4- Carbon Oxalo Acetic Acid (O AA) .
2 The first product is a 4 - Carbon and so it named as `C_(4)` cycle . Oxalo Acetic Acid is a dicarboxylic acid and hence this cycle is also known as Dicarboxylic Acid Pathway .

Stage : I Mesophyll Cells
Stage II Bundle sheath cells :
1 Malic acid undergoes decarboxylation and produces a 3 carbon compound Pyruvic acid released to the phloem .
2 The released `CO_(2)` combines with RUBP and follows the Calvin Cycle and finally sugar is released to the phloem .
3 Pyruvic acid is transported to the mesophyll cells . `underset((5C))(RUBP) + CO_(2) overset("Rubisco")(to) 2 underset((3C))(PGA)`
4 Carbon dioxide fixation takes place in two places in mesophyll and another in bundle shealth cell (Di Carboxylation Pathway) .
5 It is the adaptation of Tropical and Sub Tropical plants growing in warm and dry condition.
6 Fixation of `CO_(2)` with minimal loss is due to photorespiration. `C_(4)` plants 5 ATP and 2 `NADPH + H^(+)` to fix one molecule of `CO_2`