I am a mode of respiration. I am present in aquatic animals like fishes . Who am I ?

I am like a policeman. Who am I____?

I am the mode of respiration in unicellular , Hydra and planarians . Who am I ?

lam the excretory system present in star fish. Who am I ?

I am a type of respiratory system present in most of the arthropods like grasshopper and cockroach . Who am I ?

I am cooked on steam. Who am I?

I am the structural and functional unit of lung. Who am I ?

I am the structural and functional unit of lung. Who am I ?

I am the structural and functional unit of kidneys. Who am I ?

I am present in leaf . I am very useful in gaseous exchange . Who am I ?

I am a plant. I am making the soil nitrogen rich. Who am I ?