

Respiration
 Respiration:
cells break down simple food
molecules such as sugar and release the energy
they contain
 Cells
store energy in the form of carbohydrates
1. sugars
2. starches
 Energy
stored in cells is like a savings account
 During
photosynthesis, plants capture energy from
sunlight and “save” it
 When
cells need energy, they “withdraw” it by
breaking down the carbohydrates for energy
 Respiration
can mean two different things:
1. Breathing: moving air in and out of your lungs
2. Cellular Respiration: process that takes place
inside cells
 Stage
1
o Takes place in the cytoplasm of the organism’s cells
o Molecules of glucose are broken down into smaller molecules
o NO oxygen is involved and only a small amount of energy is
released
 Stage
2
o Takes place in mitochondria
o Small molecules are broken down into even smaller
molecules
o Require oxygen and release a great deal of energy
sugar
oxygen
Raw materials
water
carbon dioxide
Products
 Can
you notice anything familiar about the equation for
respiration?
o It is the opposite of the equation for photosynthesis
 During
photosynthesis, carbon dioxide and water are
used to produce sugars
 During respiration, sugar glucose and oxygen are used
to produce carbon dioxide and water
 These
two processes form a cycle that keeps the levels
of oxygen and carbon dioxide fairly constant in Earth’s
atmosphere
 an
energy releasing process that does not require
oxygen
 fermentation
releases less energy than respiration

Alcoholic Fermentation
o Occurs when yeast and some other single-celled organisms
breakdown sugars
o The products are: alcohol, carbon dioxide, and small amount of
energy
o Important to bakers and brewers

Lactic-Acid Fermentation
o Muscle cells use up the oxygen faster than it
could be replaced
o One product of this type of fermentation is lactic acid
o It is a painful sensation in your muscles, muscles feels weak and
sore