Florida Biology 1 EOC classification and evolution: a complete overview of taxonomy, the evidence for evolution, natural selection, and the mechanisms of evolutionary change

What the classification and evolution content demands

The classification and evolution content is the heart of Reporting Category 2, Classification, Heredity, and Evolution (about 25 percent of the Florida Biology 1 EOC, shared with the genetics content). The unifying idea is common ancestry: classification groups organisms by their evolutionary relationships, and evolution explains how those relationships arose. The recurring themes are patterns and cause and effect.

This guide ties together the matching topic pages, each with its own practice questions: classification: domains and kingdoms, the evidence for evolution, natural selection, mechanisms of evolution, and mutations and genetic variation.

Classification

Organisms are classified in a hierarchy from broad to specific: domain, kingdom, phylum, class, order, family, genus, species. The three domains are Bacteria, Archaea (prokaryotic), and Eukarya; the six kingdoms are Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia. Each species gets a two-word scientific name (genus and species). Classification is based on evolutionary relationships and changes as new evidence (especially DNA) reveals those relationships more accurately.

The evidence for evolution

Evolution is supported by many independent lines of evidence: the fossil record (change over time, transitional forms), comparative anatomy (homologous structures, same anatomy, different function, from a common ancestor), comparative embryology (similar early development), biogeography (distribution reflects history), molecular biology (more similar DNA means a more recent common ancestor), and observed change (antibiotic resistance now). Distinguish homologous structures (common ancestry) from analogous ones (same function only).

Natural selection

Natural selection needs four conditions: overproduction, inherited variation, a struggle to survive, and differential reproductive success. Favorable inherited traits become more common over generations, so the population becomes adapted. Fitness means reproductive success, not strength. The key point: selection acts on existing variation, and organisms do not choose or develop traits because they need them. Antibiotic resistance is the classic worked example.

The other mechanisms

Besides natural selection, the gene pool changes through: genetic drift (random change, strongest in small populations; the bottleneck and founder effects), gene flow (movement of alleles between populations by migration), non-random mating (choosing mates by trait), and mutation (new alleles). Unlike selection, drift and mutation are random with respect to fitness.

Mutations and variation

Genetic variation is the raw material of evolution. Mutation creates new alleles and is the ultimate source of variation; its effect can be harmful, neutral, or beneficial. Genetic recombination in sexual reproduction (crossing over, independent assortment, and random fertilization) shuffles existing alleles into new combinations. Asexual reproduction makes identical copies with no new variation.

Check your knowledge

A mix of recall and reasoning questions covering classification and evolution. Attempt them under timed conditions, then check against the solutions.

1. List the levels of classification from broadest to most specific. (2 marks)
2. Name the three domains. (3 marks)
3. State what homologous structures are and what they provide evidence for. (2 marks)
4. Explain how DNA similarity indicates an evolutionary relationship. (2 marks)
5. State the four conditions required for natural selection. (2 marks)
6. Explain why antibiotic resistance spreads in a bacterial population. (2 marks)
7. State the difference between genetic drift and gene flow. (2 marks)
8. State the three possible effects of a mutation. (2 marks)
9. Explain how genetic recombination increases variation. (2 marks)