Imithi kunye nenkanga zifunxa amanzi kunye necarbon dioxide zize sikhuphe ioxygen enokukhanya kwelanga ukuze kwenzeke iswekile. kuyaphikisana ke noko kwenzeka kwizilwanyana xa ziphefumla. Izityalo nazo ziyaphefumla zisebenzisa i- oxygen kanye njengezilwanyana. Ziphila nge-oxygen ne-carbon dioxide.