Sentence:  In the absence of additions to the homogenate , the product formed <WSD>is</WSD> an iodinated particulate protein ( Fawcett and Kirkwood , 1953 ; Taurog , Potter and Chaikoff , 1955 ; Taurog , Potter , Tong , and Chaikoff , 1956 ; Serif and Kirkwood , 1958 ; De Groot and Carvalho , 1960 ) . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)