The main photosynthesizers in the sea are single-celled organisms called phytoplankton. They produce a large fraction of the oxygen that we breathe, form the based of the marine food web, and help take up much of the carbon dioxide in the atmosphere. They are also a great introduction to the concept of cells. This lesson will review three distinct types of phytoplankton: diatoms, dinoflagellates, and cococcolithophores. To tie in these important photosynthesizers with the concept of a cell, students will build a model of these cells, complete with organelles and the appropriate cell wall. They will also compare their models with a prokaryotic cyanobacterium cell, another important photosynthesizer in the oceans.

  • Students will know about the distinct groups of photosynthesizers: cyanobacteria, diatoms, dinoflagellates, and coccolithophores.
  • Students will know that these are the main primary producers of the sea.
  • Students will know the types of habitats these organisms prefer.
  • Students will have a review of the organelles of a cell.
  • Students will know the difference between a prokaryotic cell and a eukaryotic cells.
  • The main photosythesizers of the sea are multicellular and large, like on land.
  • All phytoplankton are the same.
  • At the very least, phytoplankton are all the same size.
  • Phytoplankton are not found everywhere in the surface of the ocean.
  • There is nothing common to a land plant cell and a marine phytoplankton cell.
  • Students will be given a brief lecture on the different types of phytoplankton and cyanobacteria in the sea and their preferred habitats. The lecture can be found in the file Phytoplankton Cell Model Presentation.
  • Following the presentation, students will build models of phytoplankton cells.
  • Instructions for the students can be found in the document Phytoplankton Cell Model Building Instructions.
  • Chalk.
  • Flat marbles.
  • Wood chips.
  • Play-doh.
  • Small cupcake liners.
  • String.
  • Sour punch straw pieces.
  • Raw sugar.
  • Yarn.
  • Ribbon.
  • Beans .
  • Split peas.
  • Toothpicks.
  • Pipe cleaners.
  • Small marshmallows.
  • Large marshmallows.
  • Paper towels.
  • Scratch paper.
  • Disposable bowls.
  • Construction paper.
  • Red hots.
  • Gushers.
  • Rice.
  • Nonpareil sprinkles.
  • Glue.
  • Copies of the worksheets Phytoplankton Cell Model Building Instructions, Cell Labeling Worksheet, and Cell Model Questions Worksheet.
  • This activity is the first of three in the unit “Community Structure and Dynamics of Marine Plankton.”
  • This learning activity is to be used in a 10th grade biology classroom.
  • It is best suited for a 90-minute class.
  • This activity can be adapted for different class sizes.
  • Students may work alone for small class sizes (10-20 students), or in pairs for larger class sizes (20-40 students).
  • Prior knowledge for this activity includes information about the organelles of a cell and the difference between prokaryotic and eukaryotic cells. With that prior knowledge, this is a stand-alone activity.
  • The final product is a cell model of one of the major groups of phytoplankton.
  • Students will fill out a worksheet and label their cell parts when they are finished building their cell model in order to reinforce the important concepts from this lesson.
  • The documents to fill out include the Cell Model Questions Worksheet and the Cell Labeling Worksheet.
  • See Expanded Teaching Notes document and How to Make a Cyanobacterium Cell Model for further information on how to prepare for and run this activity.



Related Community
Structure and Dynamics of
Marine Plankton Activities
Lesson Specifics
  • Grade Level: 10, biology classroom.
  • Time Frame: 90 minute class.
  • California State Biology Science Standards: Primary standards 1a and 1c are covered. Secondary standards 1e, 1f, 1g, and 1j are covered.

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