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4.1: Planning

Difficulty Level: At Grade Created by: CK-12
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Key Ideas

  • The life of a cell depends on the activities that take place within it and also on the environment surrounding it.
  • Enzymes help chemical reactions take place inside the cell. They help build products, make copies of molecules, and carry out cell functions efficiently.
  • The selectively permeable cell membrane allows water to pass through it, but not large molecules dissolved in water.
  • Passive and active transport are the processes by which substances move in and out of the cell.
  • Cellular respiration requires oxygen and produces ATP, the energy needed for the cell to do its work.
  • Cell division is one of the important events of the cell cycle.


Following the study of the cell parts and their functions in the previous section, students explore the important cell activities of cellular respiration, the transport of molecules, and cell division. Students investigate enzymes and explore factors that affect their activity. They also simulate each stage of mitosis and meiosis using pipe cleaners to represent chromosomes.



identify and explain the important functions of enzymes.

explain the processes of osmosis and diffusion.

simulate the processes of mitosis and meiosis.


active transport, cell cycle, cellular respiration, diffusion, diploid, enzymes, gamete cells, haploid, meiosis, mitosis, osmosis, passive transport, somatic cells

Student Materials

Activity 3-1: Catalysts and Enzymes in Your Life

  • Data Table
  • Activity Report
  • Goggles for each team member
  • Test tubes (5 per team); Test tube rack; Test tube holder; Marking pen/pencil for test tubes; Graduated cylinder; Forceps; Stirring rod; Hydrogen peroxide (H2O2-3%); Sand; Manganese dioxide (MnO2); Wood splints; Paper towels; Liver cell samples (cooked and uncooked)

Activity 3-2: Cell Division-Double or Nothing

  • Resources 1 and 2
  • Activity Report
  • Crayons or colored pens or pencils (same colors as pipe cleaners if possible); Large paper plates (2); Eight pipe cleaners (2 long of color A, 2 long of color B, 2 short of color A, and 2 short of color B)

Teacher Materials

Activity 3-1: Catalysts and Enzymes in Your Life

  • Activity Report Answer Key
  • Goggles
  • Data Table (Optional: to be used if students do not design their own or as a model); Extra test tubes, splints, hydrogen peroxide and paper towels should be available; Liver cell samples (uncooked, cooked, and uncooked soaked in vinegar); Test tube brushes at sinks; Wooden splints and matches, for demonstration to identify gas bubbles as oxygen

Activity 3-2: Cell Division-Double or Nothing

  • Activity Report Answer Key
  • Additional student supplies
  • Resources 1 and 2 (Optional)

Advance Preparation

See Activities 3-1 and 3-2 in the Student Edition.

Activity 3-1: Catalysts and Enzymes in Your Life

  • Review student pages relating to enzymes.
  • Gather and prepare necessary lab materials.
  • Purchase fresh liver from a local butcher preferably one or two days before the activity. Keep refrigerated until use.
  • Prepare three liver samples, one cubic centimeter in size, for each team.
  • Each team needs
    • one piece of fresh liver, best prepared on the day of the activity.
    • one piece of fresh liver that has been thoroughly cooked for 5-10 minutes in a microwave. It is recommended that the samples be placed in a small amount of water and covered before microwaving, in order to prevent drying out. Cooked samples can be stored overnight in a refrigerator.
    • one piece of fresh liver that has been soaked overnight in vinegar.
  • If time is limited, copy the Data Table for student use.

Activity 3-2: Cell Division-Double or Nothing

  • Collect student materials.
  • Make copies of Resources 1 and 2 if you plan to do the Optional extension of this activity.

Interdisciplinary Connection

Art Students make models, pictures, or diagrams to illustrate how enzymes work.

Enrichment Activity

Enrichment 3-1: Exploring Osmosis

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