A cooperative effect can occur in some types of multi-subunit proteins, leading to improved function of the subunits when bound to each other. At what level of protein structure does this function arise?

1. in what ways have non-native species been beneficial? 2. what are some of the hypotheses for the collapse of honeybee colonies? 3. distinguish between regional and functional extinction. 4. why is it difficult to measure background extinction rates? 5. what three factors are most important in causing extinction rates to climb?