The cell is the basic unit of structure and function of a living thing.
Cells are specialized by size and shape for the job they do
Examples: human blood cell, sperm cell, neuron (nerve cell)
Tissues are made of a group of similar cells that work together to do a specific job in the body.Examples: connective tissue, muscle tissue, nervous tissue
Organs are made up of two or more tissues that work together to do a specific job.Example: liver, kidney, heart
An organ system is a group of organs working together to perform particular jobs.
Example: skeletal system, muscular system, nervous system
Sum of all cells, tissues, organs and organ systems makes an organism. An organisms is made when a group of organ systems work together
example: Animals, plants, and humans are multicellular organisms while bacteria is an unicellular organism
A group of the same type of organisms all living together in the same place
Populations living together in one area
All the ecosystems around the world make up the biosphere