Discovery Of Photosynthesis Biology Worksheets printable pdf download

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Discovery of Photosynthesis

DIRECTIONS. Many scientists contributed to the discovery of photosynthesis. Read the following

passage about the discovery of photosynthesis & create a timeline in the chart that follows.

The discovery of photosynthesis cannot be attributed to one scientist’s experiments. Rather,

several scientists have performed experiments that have led to our current understanding of

photosynthesis. The contributions of 5 of these scientists are described below.

In 1643, Jan Baptista Van Helmont did the first

biological experiment in which all ingredients were measured

accurately and all changes noted precisely.

From his

experiment, Van Helmont concluded that a willow tree drew

its nutrients, not from the soil, but from water. He was

mistaken in concluding the material that made up the bark,

wood, roots and leaves came from the water he had added

over the five years. It wouldn’t be until the 1800s that it was

correctly understood where the mass of a tree came from.

The next important step in the understanding of

photosynthesis came in the early 1770’s. Joseph Priestly, the British man recognized for discovering

oxygen in 1774, discovered that when he placed a candle in an enclosed jar, the candle would burn out

very quickly, much before it ran out of wax. He called the air inside the jar “injured.” He further

discovered that a mouse could similarly "injure" air. He

then showed that the “injured" could be restored by a

plant. One day , Priestly accidentally placed the jar

with the candle and plant in a dark corner of his

laboratory.

The candle’s flame extinguished, but

Priestly never explored the role that light played in his

observation.

In 1778, Dutchman Jan Ingenhousz, court

physician to the Austrian Empress, repeated Priestley's

experiments (with a few alterations). It had been noticed

that submerged plants gave off small bubbles and, if the

plants were placed in the shade, these bubbles eventually

stopped. Ingenhousz carried out a series of experiments

to prove that the bubbles were independent of heat and

Discovery Of Photosynthesis Biology Worksheets