The Seven Characteristics of Life

Living things are composed of cells:

·         Single-cell organisms have everything they need to be self-sufficient.

·         In multicellular organisms, specialization increases until some cells do only certain things.

Living things have different levels of organization:

·         Both molecular and cellular organization.

·         Living things must be able to organize simple substances into complex ones.

·         Living things organize cells at several levels. Tissue is a group of cells that perform a common function. An organ is a group of tissues that perform a common function. An organ system is a group of organs that perform a common function. An organism is any complete living thing.

Living things use energy:

·         Living things take in energy and use it for maintenance and growth.

Living things respond to their environment:

·         Living things will make changes in response to a stimulus in their environment.

·         A behavior is a complex set of responses.

Living things grow:

·         Cell division is the orderly formation of new cells.

·         Cell enlargement is the increase in size of a cell. Cells grow to a certain size and then divide.

·         An organism gets larger as the number of its cells increases.

Living things reproduce:

·         Reproduction is not essential for the survival of individual organisms, but must occur for a species to survive.

·         All living things reproduce in one of the following ways: asexual reproduction is producing offspring without the use of gametes, and sexual reproduction is producing offspring by the joining of sex cells.

Living things adapt to their environment:

·         Adaptations are traits giving an organism an advantage in a certain environment.

·         Variation of individuals is important for a healthy species.