 Although cadmium has no known biological function in higher organisms , a cadmium @-@ dependent carbonic anhydrase has been found in marine diatoms . 
 Although cadmium <a href='got' title='1'><mark>has</mark></a> no known biological function in higher organisms , a cadmium @-@ dependent carbonic anhydrase <a href='been_done' title='2'><mark>has</mark></a> been found in marine diatoms . 
Although cadmium got no known biological function in higher organisms , a cadmium @-@ dependent carbonic anhydrase done been found in marine diatoms .