This is because the leaf would not have tiny oxygen bubbles spread across its base (because the base is where most stomata are) that would help it float on the water. The reason is that the oxygen produced in the process of photosynthesis would be consumed in respiration because the rates of the two biochemical processes are the same.
Number <u>3</u> is the chloroplast. The chloroplast helps the plant obtain food by <u>photosynthesis</u>. Number <u>1</u> is the central vacuole. The central vacuole helps a plant maintain its structure by <u>turgor pressure</u>.