4.2 Respiration
7.1.d Students know that mitochondria
liberate energy for the work that cells do
and that chloroplasts capture sunlight
energy for photosynthesis.
What is Respiration?
 Respiration-
the process but which cells obtain
energy from glucose
 Key Concept: “During respiration, cells break
down simple food molecules such as sugar and
release the energy they contain.
 Cells of all living things carry out respiration
because they need energy
 Cells store energy like we store money in a bankcapture energy from sun and save during
photosynthesis- when need energy the break
down carbohydrates in respiration
Two Stages of Respiration
 During
respiration, cells break down
simple food molecules such as sugar and
release the energy they contain.
What is Respiration?
2
meanings for respiration- cellular respiration
and breathing
 Products of respiration-carbon dioxide and water
 We breathe out carbon dioxide
 Plants undergo Photosynthesis and make its own
food (sugar)
 Animal cells (and some others) get their glucose
from eating plants or animals that ate plants
 Respiration and Photosynthesis keep levels of
oxygen constant on Earth
 Respiration video
What is Respiration?
 Respiration
Sugar
equation:
Oxygen
Yields
 Raw
Carbon
Dioxide
Materials
Video on Cellular respiration
Water
Products
Photosynthesis and Respiration

You can think of photosynthesis and respiration
as opposite processes.
The 2 Equations
+ energy
Fermentation
 Fermentation-
energy
releasing process does
not need oxygen
 Key concept:
“Fermentation provides
energy for the cell
without using oxygen.”
 Amount of energy
released is less than
during respiration
Mitochondria
Fermentation- Alcoholic
 Type
of fermentation when
yeast and some other single
celled organisms break down
sugars
 Called alcoholic because one
of its products is alcohol
 Other products are carbon
dioxide and energy
 Important to bakers- raises
dough and creates bubbles in
alcohol drinks
Fermentation- Lactic Acid
 Takes
place at times in your
body
 When running muscle cells use
oxygen faster than it can
replace it
 Cells lack energy and
fermentation occurs
 Product is lactic acid
 When the lactic acid builds
up you feel pain (and
weakness) in your muscles
Section 2: Respiration
What events occur
during respiration?
What is fermentation?