There are 6 key characteristics of living things: 1) cells, 2) response to stimuli, 3) reproduction, 4) DNA, 5) metabolism, and 6) growth and development. All living things also require 4 basic necessities to survive: water, air, food, and shelter. Within cells, there are 5 main types of molecules that serve as building blocks: proteins, carbohydrates, lipids, ATP, and nucleic acids. Each plays an important role in the structure and functions of living organisms.

1. Characteristics of Living Things
& Necessities of Life

2. There are 6 characteristics of
living things
What makes something living or
nonliving?

3. All living things are composed of
one or more cells
What is a cell? A cell is a
membrane –covered structure
that contains all the material
necessary for life
Unicellular= one cell;
multicellular = more than one
cell
#1: Living Things Have Cells

4. A stimulus is a change that affects
the activity of an organism.
Examples: chemicals, gravity, light,
sound, hunger, or anything else
that activates a response
Homeostasis is the maintenance of
a stable internal environment.
Allows us to keep our internal
environment in check when
external environment is changing
#2: Living Things Sense and Respond
to Change

5. Sexual reproduction:
two parents produce
offspring that is similar
to both parents
Asexual reproduction:
single parent produces
offspring that is
identical to the parent
#3: Living Things Reproduce

6. The cells of ALL living things contain the molecule
“deoxyribonucleic acid” or DNA
DNA controls structure and function of the cell
Heredity: passing copies of DNA from parent to
offspring
#4: Living Things Have DNA

7. Organisms need and
use energy to carry
out activities in life.
Metabolism: the total
of all the chemical
activities that the
organism performs
#5: Living Things Use Energy

8. We all GROW! It doesn’t
matter if you are a
multicellular or unicellular
organism
We all develop! As we
grow, we go through different
stages in our lives
#6: Living Things Grow and Develop
Example: Baby > Child > Teen > Adult

9. Organisms need 4 things to live
Necessities of Life

10. Your body is made
up of 70% water
Most of the
chemical reactions
involved in
metabolism require
water
1. Water

11. A mixture of gases (oxygen and
carbon dioxide)
Organisms on land get oxygen
from the air
Marine animals get dissolved
oxygen from the water or by
coming up for air
Green plants, algae, and some
bacteria need carbon dioxide in
addition to oxygen to undergo
their food making process called
photosynthesis
2. Air

12. Gives us energy and raw materials
needed to carry on life processes
such as replacing cells
Producers: make their own food
Consumers: get food by eating
other organisms
Decomposers: break down
nutrients of dead organisms or
animal wastes
3. Food

13. 1. Proteins
2. Carbohydrates
3. Lipids
4. ATP
5. Nucleic Acids
5 Building Blocks of Cells

14. Proteins: molecule made
up of amino acids; helps
build and repair body
structures
Example: protein
hemoglobin is in red blood
cells and binds to oxygen
to deliver it throughout
the body
Proteins

15. Carbohydrates: molecules
made up of sugars
A. Simple carbohydrates:
one sugar molecule, like
table sugar
B. Complex carbohydrates:
hundreds of sugar
molecules, such as starch
(potato, whole wheat)
Carbohydrates

16. Lipids: do not dissolve in
water; include fats and
steroids
Phospholipids are the
molecules that form
much of the cell
membrane; the head is
attracted to water but
the tail is not- the tails
attract and form two
layers
Lipids

17. ATP: “Adenosine Triphosphate”; major
energy-carrying molecule in the cell; provides
energy for the cell
4. ATP

18. Nucleic acids: have all
the information a cell
needs to make
proteins
DNA is a nucleic acid
5. Nucleic Acids

19. All living things need a place to live that has all the
necessities of life (enough space, food, water, etc.)
4. Shelter (a place to live)