Question

Is lettuce a C3 or C4 plant?

Answer 1

C3 Plants:

1. C3 plants refer to all the plants, which carry out carbon fixation by the C3 pathway in the second stage of photosynthesis, i.e. dark reaction.
2. In C3 plants atmospheric carbon dioxide directly enters the Calvin cycle and the first product formed is the 3 carbon compound known as 3-phosphoglyceric acid (3PGA).
3. RuBP (5C) is the acceptor of CO2.
4. All these C3 featues are observed in lettuce, that why these are C3 plants.

C4 plants:

1. C4 plants possess a special type of anatomy called the kranz anatomy, in which inner ring of bundle sheath cells which is surrounded by mesophyll cells.
2. The initial acceptor of CO₂ is PEP (phosphoenol pyruvate).
3. First stable product is OAA (oxalo acetic acid) which is 4 carbon product hence named C₄ cycle.
4. Another feature is presence of dimorphic chloroplast.
5. All these features are not shown by lettuce, thats why these are not C₄ plants.