Question

how is excretion of plant useful to human beings

Answer 1

there are many uses of plant excreta for example as we excrete co2 during respiration In the same way plants excrete O2, which is most useful gas for our metabolic activities.

some more excretory products which are useful to human beings:

1. Tannin is an excretory product which is stored in leaves. and we use it as tea
2. caffeine, latex, Chile,etc.,