Photosynthesis, the process by which plants turn CO2 and H2O into sugar and O2, was mentioned in this video and is affected by the quantities and types of pigments present in leaves. Explore here and here to find out how different colored pigments affect light absorption and why many leaves are green.Why do some regions experience full-time heat while others are reckoning with frigid temperatures and snow? And why are the seasons reversed in the two hemispheres? Rebecca Kaplan explains how the shape of the Earth's orbit around the Sun and the Earth's tilt on its axis affect the amount of sunlight each region receives.Photosynthesis is an essential part of the exchange between humans and plants. Amanda Ooten walks us through the process of photosynthesis, also discussing the relationship between photosynthesis and carbohydrates, starch, and fiber -- and how the air we breathe is related to the food we ingest.