A second set of channels, the phloem, found just under a tree's bark, carries the products of photosynthesis to the roots.

第二组通道叫韧皮部，就长在树皮之下，它将光合作用的产物输送到树的根部。

Product of photosynthesis, which explains the fussy vegetable preference for visible light...

光合作用的产物，解释了对可见光的挑剔的蔬菜偏好。

And since oxygen, or O2, is the product of photosynthesis, our atmosphere changed eventually creating the ozone layer which acted to shield the Earth from the sun's deadly light.

由于氧气，或称O2，是光合作用的产物，我们的大气最终发生了变化，产生了臭氧层，它的作用是保护地球免受太阳致命光线的照射。