Levels of Organization
In unicellular (single-celled) organisms, the single cell performs all life functions. It functions independently. Bacteria are single-celled organisms. However, multicellular (many celled) organisms have various levels of organization within them. Individual cells may perform specific functions and also work together for the good of the entire organism. The cells become dependent on one another. Plants and animals are examples of multicellular organisms. Multicellular organisms have the following 5 levels of organization ranging from simplest to most complex:
Cells, of course, are the first level of organization.
Cells, of course, are the first level of organization.
- Are the basic unit of structure and function in living things.
- May serve a specific function within the organism
- Examples- blood cells, nerve cells, bone cells, etc.
In any multicellular organism, cells rarely work alone. Cells that are similar in structure and function are usually joined together to form tissues. Tissues are the second level of organization.
- Made up of cells that are similar in structure and function and which work together to perform a specific activity
- Humans have 4 basic tissues: connective, epithelial, muscle, and nerve.
Tissues are further organized in organs, the third level of organization in living things. Organs are groups of different tissues that work together.
- Made up of tissues that work together to perform a specific activity
- Examples - heart, brain, skin, stomach etc.
Like cells and tissues, organs seldom work alone. They "cooperate" with one another and form specific organ systems. Organ systems are the fourth level of organization in living things. An organ system is a group of organs working together to perform a specific function for the organism.
- Groups of two or more tissues that work together to perform a specific function for the organism.
- Examples - circulatory system, nervous system, skeletal system, etc.
- The Human body has 11 organ systems - circulatory, digestive, endocrine, excretory (urinary), immune(lymphatic), integumentary, muscular, nervous, reproductive, respiratory, and skeletal.
Every living thing is an organism. You are an organism. Dogs, trees, and lizards are also organisms. Even a unicellular bacterium is an organism. An organism is an entire living thing that carries out all the basic life functions. The organism is the fifth level of organization.
The smooth functioning of a complex organism is the result of all its various parts working together.
The smooth functioning of a complex organism is the result of all its various parts working together.
- Organisms are living things that can carry out all basic life processes. Organisms take in materials, release energy from food, release wastes, grow, respond to the environment, and reproduce.
- Multicellular organisms are made up of organ systems, but an organism may be made up of only one cell like bacteria or protist.
- Examples - bacteria, amoeba, mushroom, sunflower, human
Journal Drawing
1. Create and entry in your journal titled "Levels of Organization". Sketch and label the diagram below to the best of your ability. Note that the diagram depicts the levels of organization from Most Complex to Most Simple.
2. Write and define each of five terms identified in the picture below. Identify an example for each level or organization as well. Use the reading passages above for reference information.
2. Write and define each of five terms identified in the picture below. Identify an example for each level or organization as well. Use the reading passages above for reference information.
Brain Pop - Body Systems
Socrative Quiz
2. Log in to Socrative to take a review quiz. My room number is 790969. Be sure to enter your first and last name and log out of the room once you have finished your test.