During prophase, when cell chromosomes become visible, what are the duplicated strands called? what is the name for the area in which these duplicated strands are joined?

Duplicated strands are known as sister chromatids. The centromere binds these two chromatids in the center. The protein used is cohesin.

The rate that would change would be the  searching efficiency/attack rate. there are only two other rates in this model: the  growth rate of prey, and the  predator or consumer mortality rate.the  searching efficiency/attack rate is what indicates how effectively can a predator capture its prey whether in the searching process or actual capturing/attacking process.