SCIENCE 7
MS. ETRI
TOPIC 2: WHAT IS LIFE?
ORGANISM: ______________________________________________!
https://www.youtube.com/watch?v=juxLuo-sH6M
6 CHARACTERISTICS OF LIFE
WHAT DO ALL LIVING THINGS HAVE IN COMMON?
1. CELLULAR ORGANIZATION

All organisms are composed of ___________________.
o
A cell is the __________________________________________________________
____________________________________in an organism.
o
The smallest cells are so tiny, over a million could fit in the period at the end of this
sentence.
o

We use _______________________________to observe cells.
Organisms may be unicellular or multicellular.
o
UNICELLULAR: _______________________________________________________

Ex. _______________________________

One cell carries out all of the functions necessary for the organism to stay
alive!
o
MULTICELLULAR: _____________________________________________________
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SCIENCE 7
MS. ETRI

Cells are ____________________________________ to perform different
functions

Ex. of differentiation:
__________________________________________________________
_________________________________________________.

Ex. of organisms: ____________________________________
2. THE CHEMICALS OF LIFE

The cells of all living things are made up of
____________________________________.

What is the most abundant chemical in our body?
________________________________

Examples of other chemicals?
o
____________________________________
o
____________________________________
o
____________________________________
o
____________________________________
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SCIENCE 7
MS. ETRI
3. ENERGY USE

Energy is used for ____________________________________

Cells are always working
o
Ex. Stomach cells are ____________________________________
o
Ex. Red blood cells are moving oxygen throughout your body
4. GROWTH AND DEVELOPMENT

GROWTH: ____________________________________
o

Does not continue throughout life.
DEVELOPMENT: the ____________________________________that occurs during an
organism’s life to produce a ____________________________________
o

Continues throughout life.
But icicles grow longer as more water freezes on their tips?!
o
Yes, but icicles are not using energy to change and grow. They do not become more
complex over time either.
5. RESPONSE TO SURROUNDINGS

STIMULUS: a change in an organism’s surroundings that
________________________________________________________________________
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SCIENCE 7
MS. ETRI
o
Ex.
______________________________________
_____________________________________.

RESPONSE:
____________________________________________
___________________________________________.

Ex. Plants growing towards the light when placed near
a window.
6. REPRODUCTION

Defined as the ability to
____________________________________________________________________________
____________________________________________________________________________
TWO TYPES:

____________________________________: involves only one parent, and no sex cells
(egg/sperm).
o

Produce genetically____________________________________offspring.
SEXUAL: Involves two parents and sex cells (egg and sperm).
o
Produces genetically _______________________________ offspring.
o
THE 4 NEEDS OF LIVING THINGS
Yes, squirrels and trees share the same basic needs as you do!
1. ENERGY

Organisms need a source of energy to live.

____________________________ is used as their energy source.

Organisms can differ in the ways they ____________________________________.
o
Plants capture the sun’s energy and use it with carbon dioxide to make their own food.

AUTOTROPHS: ____________________________________
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SCIENCE 7
MS. ETRI

“Auto” means “self”. “-troph” means “feeder”

Therefore, autotrophs use the food they make as an energy source to
carry out their life functions.
o HETEROTROPHS: ____________________________________.

“Hetero” means “other”

Energy source is also the sun—but used as an
____________________________________

How? Heterotrophs eat autotrophs! Or they consume other heterotrophs
that ate autotrophs.

Examples: _________________________________________________.
2. WATER


Organisms need water to:
o
Obtain chemicals from their surroundings
o
Break down food
o
___________________________________
o
Move substances within their bodies
o
____________________________________
Why is water so important?
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SCIENCE 7
o
MS. ETRI
Has the ability to ____________________________________than any other substance on
Earth.

Ex. The food that your cells need dissolves in the blood and is transported throughout
your body.
o
Water makes up _______________________ of the liquid part of your body.
3. LIVING SPACE

All organisms need a place to live—to get food and water and find shelter.

Because there is a limited amount of living space on Earth, organisms may
________________________________________________________________________.
o
COMPETITION: a relationship among and between living things
____________________________________.
o
Ex. Plants compete for light.
4. STABLE INTERNAL CONDITIONS

Surroundings can change significantly—as a result, organisms must be able to keep the conditions
inside their bodies constant.

HOMEOSTASIS: the maintenance of ____________________________________despite
____________________________________ in the surroundings.
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SCIENCE 7
MS. ETRI
o
Ex. ________________________________________________________________________.
o
Ex. Barnacle above water at low tide is exposed to hours of sun and wind. At high tide the
ocean water covers the barnacle.

Without a way to keep water in its cells, the barnacle would die after many hours in the
hot sun. But fortunately it does have a way! (It closes up hard outer plates to trap a
bubble of water inside until the next high tide.)
REVIEW QUESTION
How did Pasteur’s experiment show that bacteria do not arise spontaneously in broth?
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SCIENCE 7
MS. ETRI
WHERE DOES LIFE COME FROM?
People once believed that life could suddenly appear from nonliving matter.
Ex. Flies could arise from rotting meat.
Ex. When frogs appeared in muddy puddles after heavy rains, people concluded that frogs could sprout from
the mud in ponds!!
Spontaneous generation: the (mistaken) idea that living things arise from nonliving sources.
THE EXPERIMENTS OF REDI AND PASTEUR
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SCIENCE 7
MS. ETRI
In the mid-1800’s, Louis Pasteur (a French chemist) also designed a controlled experiment to refute
spontaneous generation.
Together, the experiments of Redi and Pasteur provided enough evidence for people to understand that living
things do NOT arise from nonliving material.
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SCIENCE 7
MS. ETRI
THE NEEDS OF LIVING THINGS
Yes, squirrels and trees share the same basic needs as you do!
4. ENERGY

Organisms need a source of energy to live.

Food is used as their energy source.
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SCIENCE 7

MS. ETRI
Organisms can differ in the ways they obtain energy.
o
Plants capture the sun’s energy and use it with carbon dioxide to make their own food.

Autotrophs: organisms that make their own food

“Auto” means “self”

“-troph” means “feeder”

Therefore, autotrophs use the food they make as an energy source to
carry out their life functions.
o Heterotrophs: organisms that cannot make their own food.

“Hetero” means “other”

Energy source is also the sun—but used as an indirect way.

How? Heterotrophs eat autotrophs! Or they consume other heterotrophs
that ate autotrophs~

Examples: animals, mushrooms, and slime molds.
5. WATER


Organisms need water to:
o
Obtain chemicals from their surroundings
o
Break down food
o
Grow
o
Move substances within their bodies
o
Reproduce
Why is water so important?
o
Has the ability to dissolve more chemicals than any other substance on Earth.

Ex. The food that your cells need dissolves in the blood and is transported throughout
your body.
o
Water makes up 92% of the liquid part of your body.
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SCIENCE 7
MS. ETRI
6. LIVING SPACE

All organisms need a place to live—to get food and water and find shelter.

Because there is a limited amount of living space on Earth, organisms may compete for space.
o
Competition: a relationship among and between living things for resources.
o
Ex. Plants compete for light.
4. STABLE INTERNAL CONDITIONS

Surroundings can change significantly—as a result, organisms must be able to keep the conditions
inside their bodies constant.

Homeostasis: the maintenance of stable internal conditions despite changes in the surroundings.
o
Ex. Body’s regulation of temperature.
o
Ex. Barnacle above water at low tide is exposed to hours of sun and wind. At high tide the
ocean water covers the barnacle.

Without a way to keep water in its cells, the barnacle would die after many hours in the
hot sun. But fortunately it does have a way! (It closes up hard outer plates to trap a
bubble of water inside until the next high tide.)
REVIEW QUESTION
How did Pasteur’s experiment show that bacteria do not arise spontaneously in broth?
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