Windup Toy Alive Not alive

The Characteristics of Living Things What is life? The Characteristics of Living Things

What do you and the grubs in the grass have in common?

Key Concept: All living things… a) have cell(s) b) contain similar chemicals c) use energy to carry out life activities (metabolism) d) respond to stimuli e) grow and develop (…and eventually die! – have a lifespan) f) reproduce

An organism is a living thing

IS THE BUILDING BLOCK OF STRUCTURES IN AN ORGANISM A CELL IS THE BUILDING BLOCK OF STRUCTURES IN AN ORGANISM

UNICELLULAR ORGANISMS MADE OF ONLY 1 CELL

AN ORGANISM MADE OF MORE THAN ONE CELL MULTICELLULAR AN ORGANISM MADE OF MORE THAN ONE CELL EXAMPLES:

Living things contain similar chemicals

for example… – water is the most abundant chemical in living things - proteins and lipids (fats) are the building materials of cells

Living things use energy

Most living things depend on energy from the sun Autotroph – an organism that makes its own food in a process called photosynthesis Heterotroph – an organism that cannot make its own food

Living things react to what happens around them A stimulus is a change in an organism’s surroundings A response is an action or behavior an organism takes when it reacts to a stimulus

Living things grow and develop Growth – getting larger Development – becoming more complex These activities use ENERGY to make new cells

Living things produce offspring like oneself in a process called reproduction. Sexual reproduction – when 2 parent cells are joined to produce offspring This is how most complex (large, multi-cellular) organisms reproduce Asexual reproduction – 1 parent produces a new organism Unicellular (1-celled) organisms generally reproduce this way

Living things arise from living things through reproduction LIFE COMES FROM LIFE Living things arise from living things through reproduction

400 years ago people thought that life could arise from non-living matter.

For example, people thought mud turned into frogs and meat turned into flies.

This belief or theory is known as SPONTANEOUS GENERATION

Francesco Redi set up a controlled experiment to show that rotting meat does not turn into flies!

Louis Pasteur also conducted experiments in the 1800’s to show that bacteria could only be produced from other bacteria

The work of these scientists helped disprove the theory of Spontaneous Generation

Today scientists believe that life can only come from another living thing, usually through a process called reproduction. This theory is known as BIOGENESIS

What needs do all living things have?

The NEEDS of living things: All living things must satisfy their basic needs for… Water Food Living space or shelter homeostasis

WATER Cells are composed mostly of water Dissolves and transports chemicals throughout the body Regulates body temperature in many animals Cells are composed mostly of water

Living things need food to get energy needed for metabolism Some use sunlight energy to make their own food (autotrophs) Some cannot make their own food and must feed on other living things (heterotrophs)

All living things need living space Their living space must provide them with water food shelter or protection from the elements or other organisms

THIS STEADY STATE IS CALLED HOMEOSTASIS ORGANISMS MUST BE ABLE TO MAINTAIN A STABLE INTERNAL ENVIRONMENT EVEN WHEN EXTERNAL CONDITIONS CHANGE. THIS STEADY STATE IS CALLED HOMEOSTASIS

Some ways that many animals maintain homeostasis are… Shivering when they are cold – to create warmth Sweating when they are hot –to release heat by evaporation

Now…what do you and the grubs have in common???