Photosynthesis
Two main groups of living things:
• Plants• Animals
• In science we call them….
Autotrophs
Heterotrophs
• How do autotrophs get their energy to make food?
• How do heterotrophs get their energy?
Sunlight
By consuming something else
How do organisms obtain most of their energy?
Carbohydrates (plant material)
How do plants make carbohydrates?
• Photosynthesis• Creates glucose molecules• Glucose molecules broken
down in cells to basic unit of energy ATP
What is Energy?• Ability to do work• Where does energy come from?
• FoodGlucose molecules
• C6H12O6 = glucose
Living things use chemical energy stored in food
• Energy is stored as ATP Adenosine Triphosphate
ATP powers cell activities like:•Active transport•Protein synthesis•Muscle contractions
• Energy is released when bonds are broken between phosphates – becomes ADP (Adenosine Diphosphate)
• ADP can be recharged to ATP by adding a phosphate = stored energy
ATP vs. ADP•ATP is like a fully charged battery
•ADP is like a half charged battery
Photosynthesis
• Plants use energy from sunlight to convert water and CO2 into high-energy carbohydrates and oxygen
Equation for photosynthesis
6CO2 +6H2O C6H12O6 + 6O2
Carbon dioxide + water sugars + oxygen
light
Photosynthesis is divided into two parts:
• Light Dependent Reaction (needs sun)
• Light Independent Reaction OR Calvin cycle
Why are plants green?
What does chlorophyll do?Chlorophyll in chloroplasts
Traps energy from sunlight
LightH2O
Oxygen
CO2
C6H12O6
1st reaction:
light required
2nd reaction: no light required
Quick Quiz• What is the name of the main energy-
storing compound in living organisms?
• What are the two reactions of photosynthesis?
ATP
Light Dependent and
Light Independent (or Calvin Cycle)
• What are the two things required in the first reaction?
• What is required for the second reaction?
• What are the products of photosynthesis?
Light Energy and Water
Carbon dioxide
Oxygen and Glucose
Reason: The beakers closer to the light
should produce more oxygen bubbles because light is
required for the 1st part of photosynthesis in which water is split
and oxygen is released
Reason: Oxygen is produced during the
first stage of photosynthesis; carbon dioxide is USED during the
second stage; hydrogen from the
water is USED in the second stage to
form carbohydrates; nitrogen is not
produced/used in photosynthesis
The picture shows the results of a
demonstration using the simple water
plant Elodea. When the setup was
placed in strong light, a space
gradually appeared above the water in
the graduated cylinder containing the plant. The gas in the space above the water was mostly -