Biology 21

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Organization of Living Things I

Topic (21) Analyze evidence about embryonic development relationship to biological diversity. (HS-LS4-1)

There are many different animal classes and every animal in the world belongs to one of them. The five most well known classes of vertebrates (animals with backbones) are mammals, birds, fish, reptiles, and amphibians.

Every animal is formed from an embryo. Though some animals can ‘clone’ themselves, though some species like hydra and polyp (both similar to anemones), but everything reproduces, as in the linking up of genetic material and fertilisation with sperm and ovums, as an embryo

Flowering plants (angiosperms) create embryos after the fertilization of a haploid ovule by pollen. The DNA from the ovule and pollen combine to form a diploid, single-cell zygote that will develop into an embryo.

In fact all land plants are classified as embryophytes because they share the derived character of housing a dependent embryo protected within the parental tissue. This attribute was fundamental in minimizing desiccation as plants adapted to life on land.


Day 1 – Introduction
Day 2 – Virtual Textbook
  • Write a letter – Organization of Living Things I
  • Lab 24 – Trees and Leaves native to Haskell County



2:29 Learn Biology: Classification- The Taxonomic Hierarchy

4:53 Classification and Taxonomy

6:11 Classification of Life


Compare Contrast and Debate

Kickoff Debate Background: Land plants and most animals are subject to embryonic development.

  • Position A: High school students should only study embryonic development of animals.
  • Position B: High school students should only study embryonic development land plants.

Instructor Resources

Standard Daily Material
  • Day 1 – Standard material – introduction day
  • Day 2 – Standard material – reading day
  • Day 3 – Standard material – make a presentation
  • Day 4 – Standard material – give a presentation
  • Extra! – Enrichment and remediation options
Other Topic Specific Resources

Special Notes and Notices

Instructor Emphasis:

  • Science & Engineering Practice: Analyze and interpret data.
  • Cross-Cutting Concept: Systems and System Models.

Emphasize HS-LS4-1  Analyze and evaluate how evidence such as similarities in DNA sequences, anatomical structures, and order of appearance of structures during embryonic development contribute to the scientific explanation of biological diversity.

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