Molecular phylogeny and evolutionary relationships are the focus of this Grade 11 Science worksheet, exploring how scientists compare DNA, RNA, and protein sequences to investigate shared ancestry. Students examine how molecular evidence supports evolutionary hypotheses, why sequence comparisons require careful interpretation, and how genetic data can be combined with fossils and physical characteristics to build a more complete picture of evolutionary history.

From molecular sequences to evolutionary evidence

The reading passage introduces the role of inherited molecular information in reconstructing relationships among organisms. Students consider why closely related organisms often share more sequence similarities than distantly related groups, while recognizing that conclusions depend on which genes are examined.

Sequence alignment is presented as a method for identifying corresponding positions among molecular sequences. Students also explore how models of molecular evolution describe substitutions and account for assumptions about how genetic changes occur and accumulate over time. These concepts connect molecular comparisons with the reasoning scientists use to infer evolutionary relationships.

Explore molecular clocks and genomic comparisons

The resource examines how a molecular clock uses genetic differences and estimated substitution rates to estimate when evolutionary lineages diverged. Students learn why calibration matters, including the use of dated fossils or biogeographic events as independent evidence. They also consider why molecular-clock estimates contain uncertainty when substitution rates vary across genes and lineages.

Comparative genomics and phylogenomics extend this investigation. Comparative genomics examines genetic information across organisms, while phylogenomics uses genomic data to infer evolutionary relationships. Students evaluate how molecular evidence complements morphology, the study of physical features, and paleontology, which investigates past life through fossils. Rather than treating DNA evidence as a replacement for other scientific evidence, the worksheet emphasizes how different evidence sources can inform one another.

Apply the concepts through varied tasks

The printable activity includes a scientific reading passage, multiple-choice questions, true-or-false statements, short-answer responses, a labeled diagram, a categorization activity, and a short note. Questions address sequence alignment, molecular evolution models, molecular-clock calibration, genomic comparisons, and the interpretation of differing substitution patterns between genes.

Short-answer prompts ask students to explain why sequences must be aligned before comparison, describe how molecular clocks estimate divergence times, and justify combining molecular findings with morphological and paleontological evidence. These tasks encourage students to explain scientific methods and evaluate the limits of conclusions drawn from genetic data.

Included with the worksheet

• Grade 11 Science worksheet on molecular phylogeny and evolutionary classification.
• Student Notes lines at the bottom of the worksheet.
• A separate PDF answer key for checking responses.
• A Teacher Guide inside the Answer Key PDF, including Learning Objectives, Teaching Tips, Discussion Questions, and Common Mistakes.

Ways to use this resource

Use this molecular evolution worksheet when teaching evolutionary classification, introducing phylogenomics, reviewing evidence for common ancestry, or preparing students for an assessment. The passage establishes the scientific context before students apply key ideas, while the answer key supports response checking and the teacher guide provides material for follow-up discussion and addressing misconceptions.

TEKS is named as the curriculum framework in the supplied details. No specific TEKS code or confirmed alignment to an individual standard was provided, so this listing does not claim a particular code.