Question

On which of the following organisms did Nicolas Theodore De Saussure conduct his experiment?

• A. Blue green algae
• B. Purple and green sulphur bacteria
• C. Cladophora
• D. Periwinkle

Answer 1

The correct option is D Periwinkle

Nicolas Theodore De Saussure refuted the claims of other scientists like van Helmont who believed that only water was responsible for the plant's biomass.

In order to prove his point he took a plant (Periwinkle) which was kept in a closed container. Weight of the plant was recorded. The setup was kept in the sunlight for a few days. After that weight of the plant and the amount of CO2 present in the container were recorded again. He found that CO2 decreased and the plant mass increased.

This meant that carbon dioxide that was consumed was being used to make more plant biomass. The decrease in the mass of CO2 after exposure to sunlight was due to the fact that plants, with the help of sunlight, performed photosynthesis by using CO2.

Cladophora, a green algae was used by TW Engelmann to prove that blue and red light wavelengths optimum for photosynthesis.

Van Neil worked on green and purple sulfur bacteria to prove that oxygen released during photosynthesis was not from spliting of carbon dioxide, but from water.