What did the experiments of

van Helmont, Priestly, and Ingenhousz

reveal

about how plants grow?

The experiments performed by van Helmont, Priestly, Ingenhousz, and other scientists reveal that in the presence of light, plants transform carbon dioxide and water into carbohydrates and release oxygen.

6Co₂ + 6H₂O  light→ C₆H₁₂O₆ + 6O₂

Carbon dioxide + water light →  sugar + oxygen

Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and high-energy sugars. 

What is the overall equation

for photosynthesis?

Plants gather the sun's energy with light-absorbing molecules called pigments.  The plants' principal pigment is chlorophyll. 

 There are two main types of chlorophyll:  chlorophyll a and chlorophyll b.

What is the role

of light and chlorophyll

in photosynthesis?

photosynthesis

A process by which plants and some other organisms use light energy to power chemical reactions that convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches (pp 68, 204)

pigment

Any light-absorbing colored molecule used in trapping light energy(pg 207)

chlorophyll

A principal pigment of plants and other photosynthetic organisms; captures light energy (p. 180).

Why are light and cholorophyll

needed

for photosynthesis?

Light is a form of energy.  Chlorophyll absorbs the light energy and transfers it into electrons within the chlorophyll molecule.  With the raised level of electrons in the chlorophyll molecule - this high energy electrons make photosynthesis work. 

Jan van Helmont

• Scientist that devised an experiment to find out if plants grew by taking material out of the soil.

• 5 years, the seedling, which by then was a small tree, had gained about 75 kg.

• conclusion was that most of the mass the plant gained had come from water.

Joseph

Priestley

• Scientist that discovered that oxygen, produced by a live sprig of mint trapped under a glass bell jar, would allow a candle to burn longer.

Jan

Ingenhousz