What Is Life?
What are the characteristics of all living things?
If you were asked to name some living things, or organisms,
you might name yourself, a pet, and some insects or plants. You
would probably not mention a moss growing in a shady spot, the
mildew on bathroom tiles, or the slime molds that ooze across
lawns. But all of these things are organisms that share several
important characteristics with all other living things.
The 7 Characteristics of Life
All living things are made of cells, use energy,
respond to a stimulus, reproduce, grow and develop,
change to fit their environment (adapt), and contain DNA.
Use the following information to fill out your note sheet on the 7
characteristics of life. You will need to:
1) Write the characteristic
2) Write a description (3-4 interesting facts)
3) An example or picture
1. ALL LIVING THINGS ARE MADE OF CELLS
All organisms are made of small building blocks called cells. A cell is
the basic unit of structure and function in an organism. Organisms may be
made up of one or more cells. Single-celled organisms, like bacteria, make up
most of the living things on Earth. Single-celled organisms have everything
they need within themselves to be self-sufficient. In other words, they
contain all seven characteristics of life. In multi-cellular (made of more than
one cell) organisms, the different cells have certain jobs. For example,
humans are made up of trillions of cells such as bone cells, nerve cells and
muscle cells. Plants have leaf cells and root cells.
2. ALL LIVING THINGS USE ENERGY
The sun is the source of energy for all living things on Earth.
Organisms get energy from taking in and breaking down materials for their
cells to use. Plants trap the energy from the sun to make their own food in a
process known as photosynthesis. Other organisms eat plants to gain energy
and then are eaten themselves and provide energy for other organisms. You
are using energy just to read these words. Your eye and brain cells are hard
at work!
3. ALL LIVING THINGS RESPOND TO STIMULI
What happens when you touch a hot stove? You feel the heat and then
jerk your hand away. Have you ever seen a plant in a sunny window and
observed that the plant’s stems have bent so that the leaves face the sun.
Like a plant bending toward the light, all organisms react to changes in their
environment. A change in an organism’s surroundings that causes the
organism to react is called a stimulus (plural stimuli). An organism reacts to a
stimulus with a response- an action or change in behavior. Another example
is if you are cold, you shiver. The cold is the stimulus while the shivering is
the response. Or when you are hot, you sweat. The sweat is a response to
the stimulus- you being hot.
4. ALL LIVING THINGS REPRODUCE
Another characteristic of organisms is the ability to reproduce, or
produce offspring that are similar to the parents. Reproduction ensures the
survival of a species. Organisms reproduce in different ways. Sexual
reproduction involves two parents that combine their genetic material to
produce a new organism that differs from both parents. Mammals, birds, and
most plants sexually reproduce. Asexual reproduction involves only one
parent and produces offspring that are identical to the parent. They
basically clone themselves. Bacteria reproduce this way.
5. ALL LIVING THINGS GROW AND DEVELOP
Growth is the process of becoming larger. You are not the same size
you were 10 years ago! Development is the process of change that occurs
during an organism’s life to produce a more complex organism. You started
off as an egg cell and sperm cell joined together as one. But soon more and
more cells started forming to create your entire body such as heart cells,
skin cells, nerve cells, etc. Over time, you will develop into a mature adult
just like a caterpillar will develop into a butterfly.
6. ALL LIVING THINGS CHANGE TO FIT THEIR
ENVIRONMENT (ADAPT)
Polar bears are only found around the North Pole where it is cold and
white because of the snow and ice. When people think of the color of bears,
they usually think of them being brown or black. But polar bears are white!
Over time, polar bears grew thick fur and became white to survive in this
environment. The fur protects them from the cold and the white color helps
them blend in with the snow and ice to help them sneak up on their food!
Organisms become specially adapted to fit in their particular environments.
Penguin wings have adapted to become more like fins to swim through the
water to catch fish or to escape from a hungry whale. Most flowers are very
bright and smell good to attract insects such as bees. The bees land on the
flowers and get pollen stuck to their bodies. When they land on another
plant, the pollen will come off and fertilize that plant (reproduction).
Adaptation occurs over a very, very long period time up to millions of years.
Organisms must be able to adapt to changes in their environment or run the
risk of becoming extinct.
7. ALL LIVING THINGS CONTAIN DNA
DNA is the genetic material that carries information about an
organism and is passed from parent to offspring. DNA stands for
deoxyribonucleic (dee AHK see RY bo new KLEY ik) acid. DNA is what
provides the instructions to make you who you are. It controls everything
from how tall you are to your hair, eye and skin color. Copies of DNA are
passed from parent to offspring. This is called heredity.