There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they 14
There are many different species of bird on the Earth today.
Describe how these different species may have evolved from an ancestor such as
Archaeopteryx.

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit. there is a precise compatibility between the active site and the lactose molecule. specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed. reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.