Many biological electron transfer reactions, such as those associated with biological energy conversion, may be visualized as arising from electron tunneling between protein-bound co-factors, such as cytochromes, quinones, flavins, and chlorophylls. this tunneling occurs over distances that are often greater than 1.0 nm, with sections of protein separating electron donor from acceptor. for a specific combination of donor and acceptor, the rate of electron tunneling is proportional to the transmission probability, with κ ≈ 7 nm−1 (use the equation given ψ = ceκx + de−κx κℏ = 2m(v0 − e) 1/2 by what factor does the rate of electron tunneling between two co-factors increase as the distance between them changes from 2.0 nm to 1.6 nm? you may assume that the barrier is such that the following equation is appropriate. t ≈ 16ε(1 − ε)e−2κw