The double membrane. It's theorized that chloroplasts used to be their own single-celled organism in the environment (and therefore with its own membrane). Then, the theory states, a larger cell took in the chloroplast by endocytosis, which involves surrounding the chloroplast in the large cell's own membrane. The chloroplast would then have two membranes surrounding it. This is similar to the thinking for mitochondria becoming an organelle as well. Hope this helps! :)
Answer:
The commercial application of ethylene gas are as follows:
The ethylene gas are important for the early ripening of fruits.
The elongation of shoot can be done by ethylene gas.
The flower stimulation and swelling of stem can be achieved by the use of ethylene gas.
The leaf abscission of ornamental plants can be done by the use of ethylene hormone.
the answer is chemical reaction
