Describe the relationship between the uv index and latitude

The measure of UV index decreases with increase in latitude. This is due to the density of sunlight (per square area) that hits the low latitudes is high that at higher latitudes. This is why the populations closer to the equator have darker skins than population in higher latitudes. Melanin is meant to protect the skin from UV light that can damage genetic material.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products