Answer:
Cells are the basic building blocks of living things.
There are four major types of tissues: connective, epithelial, muscle, and nervous tissues.
Organ, in biology, a group of tissues in a living organism that have been adapted to perform a specific function.
An organ system is a group of organs that work together to perform a certain function in an organism's body.
The definition of an organism is a creature such as a plant, animal or a single-celled life form.
Explanation:
