Basic objective of this lecture is to present on Study on Plants. It is a tutorial based lecture focus on why Study Plants? This study describe on Atmospheric gas regulation: Production of oxygen gas as a by-product of photosynthesis. And, Sugars and their polymers: Oxygen gas in the atmosphere is converted to ozone in the stratosphere, as it absorbs UV light. Ozone then absorbs more UV light and is eventually converted back into oxygen gas.