[Answer] 10. All carbohydrates contain carbon, hydrogen and oxygen. All proteins contain carbon, hydrogen, oxygen and what other element?

Step 1 : Introduction to the question "10. All carbohydrates contain carbon, hydrogen and oxygen. All proteins contain carbon, hydrogen, oxygen and what other element?"

...1. Nitrogen 2. Fluorine 3. Sulphur 4. Chlorine They are the only main food component that contains an extra element.

[Ans] What organism contributes 70 to 80 percent of Earth's oxygen?

Step 1 : Introduction to the question "What organism contributes 70 to 80 percent of Earth's oxygen?"

Tiny microscopic plants are at the base of the world's marine food chain. These phytoplankton are a form of algae and they produce between 70 and 80 percent of the oxygen in our atmosphere. Good ol' pond scum, the green slick riding the waves, and even some marine seaweed beds are colonies of algae. Trees and other green plants supply oxygen and are important to Earth's ecosystem, but without marine algae, oxygen-dependent life would not survive on planet Earth. Source: Ecology.com

[Answer] What organism contributes 70 to 80 percent of Earth's oxygen?

Step 1 : Introduction to the question "What organism contributes 70 to 80 percent of Earth's oxygen?"

...Tiny microscopic plants are at the base of the world's marine food chain. These phytoplankton are a form of algae and they produce between 70 and 80 percent of the oxygen in our atmosphere. Good ol' pond scum, the green slick riding the waves, and even some marine seaweed beds are colonies of algae. Trees and other green plants supply oxygen and are important to Earth's ecosystem, but without marine algae, oxygen-dependent life would not survive on planet Earth. Source: Ecology.com