Lesson 1.1 Foundations of Life

Cells: Basic Units of Life




  • Explain the principles of the cell theory

  • Describe the levels of cellular organization in animals

Key Concept

  • Your tissues, organs, and body systems all have one thing in common - they are composed of cells. Cells are the basic units of structure and organization of all living organisms.


Tier 2 Cell
Cell theory
Tier 3 Spontaneous generation
Test Words Subdivide

Before of Lesson

Truths in Science:

  • Fact: Observations about the world around us. Example: “It’s bright outside.”
  • Hypothesis: A proposed explanation for a phenomenon made as a starting point for further investigation. Example: “It’s bright outside because the sun is probably out.”
  • Theory: A well-substantiated explanation acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. Example: “When the sun is out, it tends to make it bright outside.”
  • Law: A statement based on repeated experimental observations that describes some phenomenon of nature. Proof that something happens and how it happens, but not why it happens. Example: Newton’s Law of Universal Gravitation.

Living things have a life cycle, 5 stages:

  • Birth, Growth, Maturity, Decline, Death

Living things are classified:

The four Kingdoms include: Bacteria (prokaryote), Protista, Fungi, Plantae, Animalia

Taxonomy Human Chimpanzee
Domain Eukarya Eukarya
Kingdom Animalia Animalia
Phylum Chordata Chordata
Class Mammalia Mammalia
Order Primate Primate
Family Hominidae Pongidae
Genus Homo Pan
Species sapien troglodytes


Prior to the 17th century, there were a variety of theories about the basis of biological organisms. However, the development of the microscope quickly led to the discovery of the cell. We now know that the cell is the smallest form of matter that can carry out life processes. Aggregates of cells form the increasingly complex hierarchy of biological constructs from tissues to organisms.

Guided Practice

  • Cell Discovery and Cell Theory
  • Specialized Cells and Cellular Organization


Analyze Author’s Purpose: Sometimes, an author’s purpose is to persuade the reader to believe a certain viewpoint. One method is to provide only the information that supports the desired viewpoint. Ask students to read the section entitled “Spontaneous Generation.” Ask students to identify passages that would be included and those that would have to be eliminated if the goal were to convince a reader that spontaneous generation occurred.

Construct an Analogy: Ask students to construct an analogy between the various cells, tissues, organs, and body systems in a human with the components of a house.

Lesson Review

With students, read through the answers to the vocabulary and skill review and practice items located on pages 102-103 of the student lesson.