However Biology 2 vocal melodies is marvellous.
There is one repeat in vocal line with "You will put your good traits in" and then "You will throw your bad traits out"
However after that repeat there is just continuous flow of melody for 6 lines straight. From "You will throw your bad traits out" to "Yeah, and together we could have a genotype", every single melodic line is different with no repetition.
The vocal rise of " just like Mendel's beans" and "we could have a genotype" is heavenly. Also the contrast from the three main sections - the jerky riff, major key "Unless you've got your dominance down in your genes" and minor key in "Oh, hold me, " gives a contrasting theme like feel.
The same thing that makes me appreciate Beatles melodic songwriting is present in this song. I have to say this may well be one of the strongest set of vocal melodies in the entire album (perhaps only Slowboat surpassed it). This has the same amount of melodic flow as "This Town AIn't Big Enough for the both of us" (which also has a continuous flow of 6 line melody)
Maybe John Mc should reassess the song in terms of a bad song that you want to skip each time you listen to it. I get being annoyed by the arrangement but John Mc generally in his reviews acknowledge good songwriting marred by bad productions before (for example in MTYCDT album he thought MTYCDT and Rosebud are good songs with bad arrangement)
In anycase I think the arrangement is just a quirky arrangement that suits the lyrical topic of the song