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Reporting Category 3: Biological Evolution and Classification

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do scientists use diagrams to show the evolutionary relationships among species?

Interpret cladograms and phylogenetic trees to determine evolutionary relationships based on shared derived characteristics and molecular evidence (TEKS Biology, Reporting Category 3; patterns; systems and system models).
A TEKS-level answer on cladograms for the Texas STAAR Biology EOC: how to read a cladogram or phylogenetic tree, what nodes and branches represent, how shared derived traits group organisms, and how to judge relatedness.
11 min answer →

What different lines of evidence show that species have changed over time and share common ancestors?

Analyze and evaluate the evidence for evolution, including the fossil record, homologous and vestigial structures, and molecular (DNA and protein) similarities (TEKS Biology, Reporting Category 3; patterns; cause and effect).
A TEKS-level answer on the evidence for evolution for the Texas STAAR Biology EOC: the fossil record, homologous and vestigial structures, and molecular similarities, and how each line points to common ancestry and change over time.
11 min answer →

Besides natural selection, what factors change the genetic makeup of a population and lead to new species?

Recognize the factors that influence the genetic makeup of populations and lead to speciation, including mutation, gene flow, genetic drift, and reproductive isolation (TEKS Biology, Reporting Category 3; cause and effect; patterns).
A TEKS-level answer on the mechanisms of genetic change for the Texas STAAR Biology EOC: mutation, gene flow, and genetic drift as sources of change in a population, and how reproductive isolation leads to speciation.
11 min answer →

How does natural selection cause a population to become better suited to its environment over time?

Explain how natural selection acts on heritable variation to produce adaptation in populations over time, and identify the conditions required for it to occur (TEKS Biology, Reporting Category 3; cause and effect; stability and change).
A TEKS-level answer on natural selection for the Texas STAAR Biology EOC: variation, overproduction, the struggle to survive, differential survival and reproduction, and how this leads to adaptation and change in populations over time.
12 min answer →

How do scientists organize the diversity of life into a system that reflects how organisms are related?

Describe how organisms are classified using a hierarchical taxonomic system based on shared characteristics, and use the levels from domain to species (TEKS Biology, Reporting Category 3; patterns; systems and system models).
A TEKS-level answer on classification for the Texas STAAR Biology EOC: the hierarchical taxonomic levels from domain to species, the three domains, binomial nomenclature, and how shared characteristics group organisms.
10 min answer →