the 2LoT only pertains to closed systems by its own definition, since the universe cannot lose or gain entropy. A biological system is NOT a closed system, for the record, but as far as the law goes...
The second law is not all of thermodynamics.
The quote says: "entropy only corresponds to closed systems". That is not true. The second law isn't only about closed systems either.
It is simply stating a constraint that is significant in closed systems. Entropy and the 2nd law applies in open systems too but it doesn't constrain them in the same way.
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