第16 至 20 題為題組
One factor that separates a living thing from an inanimate object is the organism’s ability to carry out
chemical reactions that are crucial for its survival. Imagine the infinite amount of reactions that a large
organism such as human carries out every single day. 16 of these reactions are possible without
enzymes.
Enzymes consist of various types of proteins that work to drive the chemical reactions 17 for
certain types of nutrients to take effect. Enzymes can either launch a reaction or speed it up. In the absence
of enzymes, reactants may take hundreds of years to convert into a usable product, if they are able to do so
18 . This is why enzymes are crucial in the sustenance of life on earth.
Enzymes, 19 , do not always function perfectly. In 1902 Sir Archibald Garrod was the first to
attribute a 20 to an enzyme defect, which he later referred to as an “inborn error of metabolism.”
Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and
galactosemia, an error in the handling of the sugar galactose. 【題組】18. (A) at all (B) at hand (C) at first (D) at ease
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