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 -