Define ecological succession, and how it modifies communities.
Ecological succession is the change in the structure of communities over time, as they develop from the pioneer communities, which usually predominantly consist of short-lived, fast-breeding species; to climax communities containing few, long-lived species.
What is the difference between an alkene and an alkane?
Both are hydrocarbon compounds, but alkenes contain a double bond between carbon atoms which makes them an unsaturated molecule. Alkanes are saturated, and so have no double bonds between carbon atoms.
Similarities between dolphins and sharks are an example of what type of evolution?
This is an example of convergent evolution, in which species from phylogenetically disparate groups develop similar traits due to being subjected to similar selection pressures (in this case due to the selection pressures of swimming).