Question

Short /Long answer type question.
Describe the early contributions, of the following to the understanding of photosynthesis van Helmont, Priestly, Ingenhousz, de Saussure, Blackman, Hill and van Niel.

Answer 1

Jan Van Helmont wanted to prove plants use materials from the soil to perform photosynthesis. So he performed an experiment where he took a pot of soil and a willow seedling and weighed the pot of soil and the willow tree separately. After five years of performing photosynthesis, he took the tree out and weighed it. Van Helmont discovered that water was involved in increasing the mass of a plant. Priestley discovered that a plant produces the substance in the air required for burning. Ingenhousz discovered that light is necessary for plants to produce oxygen.
Joseph Priestley: The man who discovered Oxygen. One of the founding fathers of chemistry, Joseph Priestley (1733-1804) stumbled across photosynthesis, is credited with the discovery of oxygen and accidentally brought us soda water. He was also a member of BRLSI's predecessor, the Bath Philosophical Society. This showed that plants produce a gas that allows fuels to burn. This gas is oxygen.
Jan Ingenhousz. Jan Ingenhousz or Ingen-Housz FRS (8 December 1730 – 7 September 1799) was a Dutch physiologist, biologist, and chemist. He is best known for discovering photosynthesis by showing that light is essential to the process by which green plants absorb carbon dioxide and release oxygen.
Swiss botanist 1767–1845. Nicolas de Saussure was an early pioneer in plant physiology. Because the weight of carbon absorbed was less than the total weight increase of the plant, de Saussure reasoned that water is absorbed, and in so doing correctly outlined the major chemical transformations in photosynthesis.
Blackman concluded that at least two distinct processes are involved: one, a reaction that requires light and the other, a reaction that does not. This latter is called a "dark" reaction although it can go on in the light. Blackman theorized that at moderate light intensities, the "light" reaction limits or "paces" the entire process.
Cornelis Bernardus van Niel was a Dutch microbiologist whose experiments with bacteria helped explain how photosynthesis occurs in plants. Sulfur bacteria particularly interested van Niel, because there was a controversy in the early 1900s concerning the bacteria.