Which substrate fits the enzyme molecule in figure 3?

The second on is the one that fits.

Explanation:
All enzymes break their substrates (polymers) into smaller and less complex molecules (monomers) using the ‘lock and key method’, so this means that all enzymes must be in an equipped shape in order to fit their substrate and break them

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask