Living Things: Cells, Needs, and Classification
What makes something alive?
Characteristics of life
Living things are made of cells, use energy, grow, respond to their environment, reproduce, and keep internal conditions stable. Not every living thing looks the same, but these traits help scientists identify life.
Cells are fundamental
A cell is the smallest unit of life. Some organisms are made of one cell, while others are made of many cells.
What cells do
Cells take in materials, use energy, and perform life processes. In many organisms, cells work together to form tissues, organs, and organ systems.
Which is a characteristic of living things?
All living things are made of one or more cells.
Correct answer: They are made of cells
Levels of organization
Unicellular vs. multicellular
Unicellular
- Made of one cell
- Example: bacteria
- Simple but very successful
Multicellular
- Made of many cells
- Example: plants and animals
- Cells can specialize
Which is an example of a multicellular organism?
Humans are made of many cells.
Correct answer: A human
What is the smallest unit of life?
Cells are the basic units of living things.
Correct answer: A cell.
Name one thing living things need.
Living things need resources to survive and grow.
Correct answer: Energy, water, or nutrients.