Question

Who demonstrated that green plants purify the foul air produced by breathing animals and burning candles? (a) Priestley (b) Ingenhousz (c) Sachs (d) Engelmann

Short answer

Joseph Priestley demonstrated that green plants purify the foul air produced by breathing animals and burning candles.

Step-by-step solution

Understanding the Historical Context

The question is asking which scientist historically demonstrated that green plants have the ability to purify the air, which is contaminated by breathing animals and burning candles. This is related to the discovery of photosynthesis, where plants convert carbon dioxide into oxygen.

Identifying the Scientist

Research and historical records indicate that Joseph Priestley was the scientist who conducted experiments leading to the understanding that plants could 'restore' air that had been 'depleted' by candles or mice. This experiment, conducted around 1770s, paved the way for the discovery of photosynthesis.

Answering the Question

Based on the information from historical experiments regarding the purification of air by plants, we identify that the correct answer is Joseph Priestley.

Key concepts

Priestley's Experiment

In the mid-18th century, a pivotal experiment by Joseph Priestley initiated a change in how we understand the role of plants in our ecosystem. Priestley, curious about the effects of gases on combustion and respiration, placed a lit candle and a mint plant under a bell jar. He observed that when the candle extinguished, presumably using up the air, the mint plant appeared to 'refresh' the air, allowing the candle to be relit. This simple yet revolutionary experiment suggested that plants could somehow purify the air.

Priestley's findings laid the foundation for future research into plant respiration and ultimately photosynthesis. His experiment did not identify oxygen as the component of air responsible for combustion, but he had effectively demonstrated that plants release a substance that supports burning—a pivotal moment in botanical science.

Oxygen Production by Plants

The revelation that plants produce oxygen — a critical component for the survival of many organisms — was a significant breakthrough in plant physiology. Understanding that plants contribute to the renewal of air challenged prevailing theories about air composition and the interactions between living organisms and their environment.

Plants absorb carbon dioxide from the atmosphere and, through a series of light-driven chemical reactions, convert it into glucose and oxygen during photosynthesis. This oxygen production is not merely a byproduct; it is essential for maintaining atmospheric oxygen levels and hence, the balance of life on Earth. The ability of plants to convert light energy into chemical energy sustains not only their growth but also supports complex ecosystems and influences global climate patterns.

Historical Discovery of Photosynthesis

The concept of photosynthesis — the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water — is a fundamental principle of biology. Before this mechanism was understood, the role of sunlight in plant growth was a mystery. The discovery of photosynthesis correlated the light-dependent production of oxygen with plant growth, a process characterized by both Jan Ingenhousz and Jean Senebier following Priestley's initial findings.

It was Ingenhousz who noted that sunlight played a significant role in the production of oxygen by plants, while Senebier linked carbon dioxide to the process. Later, scientists like Julius von Sachs provided definitive proof of the production of starch within plant tissues, further establishing the principles of photosynthesis we know today. This progression of understanding illustrates how a succession of discoveries built upon each other to unearth the complexities of plant biology and the vital processes that sustain life on our planet.