What is Life?
Dec 29, 2015
Characteristics of Living Things
Have a cellular organization
Contain similar chemicals
Use energy
Respond to their surroundings
Grow and develop
Reproduce
Cells• A cell is a basic unit of structure and function in
an organism
How many cells are in this picture?
Unicellular Multicellular
• Single celled organism.• Bacteria • Amoeba
• Organisms composed of many cells.
• These cells are specific and programmed for
specific jobs.
Proteins
•Help cells to build things.
•Muscle is made of protein.
• Protein is found in eggs and meat.
Nucleic Acids
• Create genetic material
•DNA (deoxyribonucleic acid).
• The blueprint instructions for cells to
direct all activity.
• Cells in organisms use energy to function.
• The students in this photo are using energy to learn. Even on the cellular level that we can’t see!
• Clearly, this cat is responding to something that has scared it.
• All living things can respond to their environment
• A stimulus is what causes the organism to
react.
• A response is what action happens as a result of a stimulus.
• Living things can grow an develop.
• Development is the process of change that occurs during and organism life to produce a more complex
organism.
Spontaneous generation
The idea that life can come from a non-living
source.
This was a very popular idea during the time of
Francesco Redi.
He created a controlled experiment to test if spontaneous generation was real.
Redi’s Experiment
This is a controlled experiment.
What is the control group? What is the variable group?
Louis Pasteur
Wanted to re-test to see if spontaneous generation was true. (Most people still believed in it)
Pasteur’s Experiment
This is also a controlled experiment.
What is the control group? What is the variable group?
The Needs of Living Things
Food
Water
Living Space
Autotroph – make their own foodHeterotrph – must consume others
All organisms need water to
survive.
All organisms need a place to live – there is limited space on Earth.