Download Notes for photosynthesis and respiration I. Photosynthesis A. The

Notes for photosynthesis and respiration
I. Photosynthesis
A. The sun is the source of energy for photosynthesis
B. Photosynthesis is the process by which chloroplasts capture sunlight energy and make food for a
plant
C. Photosynthesis happens in two stages
1. Stage 1 – the phase that occurs in the light – a pigment in the chloroplast called chlorophyll
captures sunlight energy and splits water into Hydrogen and Oxygen. Oxygen leaves, Hydrogen
will be used in Stage 2. Light energy is converted to cell energy.
2. Stage 2 – Carbon dioxide and Hydrogen are used to make glucose and oxygen. Energy is
stored in the glucose.
a) oxygen and carbon dioxide move through the stomata under the leaf
D. The photosynthesis equation: 6CO2 + 6 H20
sunlight
C6H12O6 + 6O2
E. The raw materials (reactants) of photosynthesis are carbon dioxide and water, the products are sugar
(glucose) and oxygen
F. Air (carbon dioxide and oxygen) enters and leaves the plant through tiny openings underneath leaves
called stomata (pl. stoma).
G. Autotrophs, or Producers, make their own food (like plants and algae) and receive energy from the
sun directly. Heterotrophs, or Consumers, get their food by eating other organisms and receive energy
from the sun indirectly.
II. Cellular Respiration
A. During respiration, cells break down food molecules and convert them into energy that the cells can
use called ATP. (Adenosine triphosphate)
B. This occurs mostly in the mitochondria of the cell
C. Respiration is also known as the system whereby we breathe in oxygen into our lungs and exchange it
for carbon dioxide that we exhale
D. Cellular Respiration in cells has two stages:
1. Stage 1 – in the cytoplasm, glucose is broken down into smaller molecules and a small amount
of energy is released.
2. Stage 2 - In the mitochondria, the smaller molecules combine with oxygen to produce water
and carbon dioxide. This releases a large amount of cell energy, mostly in the form of ATP.
E. The respiration equation: C6H12O6 + 6O2
6CO2 + 6 H20 + ATP Energy
III. The photosynthesis and respiration equations are essentially opposites of each other! See page 53.
These two processes, photosynthesis and respiration, keep the levels of oxygen and carbon dioxide at
fairly constant levels. We as humans, however, create CO2 in abundance and are most likely changing
the planet for the worse, creating global warming.
IV) Fermentation
A) Fermentation provides energy for cells without using oxygen.
1) The amount of energy is much lower than that of respiration.
B) There are 2 main types of fermentation:
1) Alcoholic Fermentation
(a) Sugar is converted into the products of alcohol, carbon dioxide and energy.
(b) Yeast and many kinds of bacterial undergo this process
2) Lactic Acid Fermentation
(a) Sugar is converted into the products of lactic acid and energy.
(b) The muscle cells of animals (including humans) undergo this process when the muscle
lacks oxygen. This will often happen during short bouts of muscle exertion, such as a
fast run.