Transcript Chapter 2: Characteristics of Living Organisms

Chapter 2: Characteristics
of Living Organisms
Section 1: Objectives

Describe the 6 characteristics of living
things.

Describe how organisms maintain stable
internal conditions.

Explain how asexual reproduction differs
from sexual reproduction.
Characteristics of Living Things
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1.Living things have cells.
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Cells: membrane-covered structure that
contains all of the materials necessary for
life
How many cells do you have?
 Why are they important?

Characteristics of Living Things
2. Living things sense and respond to
changes in their environment.
 Stimulus: anything that causes a reaction
or change in an organism or any part of
an organism
 Stimuli can be:
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Chemicals
Gravity
Light
Sounds
Characteristics of Living Things

Even though an organisms outside
environment may change, their internal
environment must remain constant.

Homeostasis: the maintenance of a
stable internal environment
Characteristics of Living Things

Organisms must respond to external
changes in their environment.

When animals are cold, what is one way that
they respond to this change?

When animals are hot, what is one way that
they respond to this change?
Characteristics of Living Things
3. Living things reproduce.
 Organisms make other organisms similar
to themselves.

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They do this in one of 2 ways:
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Sexual reproduction: 2 parents produce
offspring
Asexual reproduction: single parent
produces offspring
Characteristics of Living Things
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4. The cells of all living things contain DNA
(deoxyribonucleic acid)

When organisms reproduce, they pass
copies of their DNA onto their offspring.
Characteristics of Living Things
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5. Organisms use energy to carry out the
activities of life.
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These activities include:
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Making food
Breaking down food
Moving materials into and out of cells
Metabolism: the sum of all chemical processes
that occur in an organism
Characteristics of Living Things
Characteristics of Living Things
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6. Living things grow and develop.

Whether an organism is unicellular or
multicellular, it grows and develops.

In addition to getting larger, living things
may develop and change as they grow.
Chapter 2 Section 1 Review Questions
1)List the 6 characteristics of living things.
 2) Give 4 examples of stimuli.
 3) Does an organism want its internal
environment to change? Explain your
answer.
 4) T/F Organisms must never respond to
changes in their external environment.
Explain your answer.
 5) What do organisms use energy to do?
 6) T/F Living things grow and develop.

Section 2: Objectives

Explain why organisms need food, water,
air, and living space.
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Describe the chemical building blocks of
cells.
Section 2: The Necessities of Life
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Living organisms need many things in
order to survive:
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Water
Air
Shelter
Food
The Necessities of Life
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1. Water
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Your cells are made up to 70% water.
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Most of the chemical reactions in your
body require water.

Different organisms require different
amounts of water.
The Necessities of Life
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2. Air

Air is a mixture of several different gases,
including oxygen and carbon dioxide.
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Organisms living on land get oxygen from air.
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Organisms living in water take in dissolved
oxygen or come to the water’s surface to get
oxygen from the air.
The Necessities of Life
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3. Shelter

All organisms need a
place to live that
contains everything
they need to survive.
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Space on Earth is
limited.
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What does this mean
for organisms?
The Necessities of Life
4. Food
 All living things need food.
 Food gives organisms energy to carry on
life processes.
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Not all organisms get food the same way:
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Producers: make their own food
Consumers: eats other organisms or organic
matter
Decomposer: eats dead/decaying organisms
The Necessities of Life
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Nutrients are made up of molecules.
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A molecule is a substance made up of one
or more atoms.
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Molecules of different atoms combine to
make compounds.
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Atoms  Molecules  Compounds
The Necessities of Life
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Almost all life processes of a cell involve
proteins.
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Proteins: molecules made up of amino
acids
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Amino acids are the subunits of proteins.
Some proteins are made up of only a few
amino acids, while others are made up of
many.
The Necessities of Life
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Molecules made up of sugar are called
carbohydrates.
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Cells use carbohydrates as a source of
energy and for energy storage.
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Simple carbohydrates are made up of one or
a few sugar molecules linked together.
Complex carbohydrates are made of
hundreds of sugar molecules.
The Necessities of Life
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Lipids: compounds that cannot mix with
water
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Lipids store energy and form the
membranes of cells.
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Phospholipids as well as fats and oils are
classified as lipids.
The Necessities of Life
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The head of a phospholipid is attracted to
water but the tail is not.
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Hydrophilic: attracted to water (“waterloving”)
Hydrophobic: not attracted to water
(“water-hating”)
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The Necessities of Life
The Necessities of Life
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ATP: Major energy carrying molecule of
the cell.
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Energy in carbohydrates and lipids must
be transferred to ATP.
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This then fuels the cell.
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ATP: Adensosine Tri-Phosphate
The Necessities of Life
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Nucleic acids: “Blue-prints” of life.
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Contain all information needed for a cell to
make proteins.
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Made up of nucleotides.
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Example: DNA