If I could point out a few roles of leafs that might get overlooked.
The obvious one, the collection of light it's the foundation of growth, leafs make food for growth via light.
They absorb co2 a vital building block for growth as we all know.
Transpiration, removing leafs kills transpiration as the surface area has been removed.
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Transpiration...
the amount of nutrient getting taken up is reduced for obvious reason.
They store starch/food that's responsible for feeding plants in the dark period,
a iodine and starch test confirms this, it's set in stone.
If you do a iodine starch test before and after lights on you get very different results, before light the leafs stays white because there's no starch available for the iodine to bond to, after light on the leaf turns black because iodine is bonding with starch the plant has made through photosynthesis.
(Science based fact)