AP BIOLOGY

Detailed explanation-1: -The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen.

Detailed explanation-2: -The gases present in the atmosphere which are responsible for the greenhouse effect are called greenhouse gases. Example Carbon dioxide, water vapor, oxides of nitrogen, methane, ozone, chlorofluorocarbons, etc.

Detailed explanation-3: -Without the atmosphere, Earth would be lifeless. Carbon dioxide (CO2) and oxygen (O2) are the most important gases for living organisms. CO2 is vital for use by plants in photosynthesis, in which plants use CO2 and water to convert the Sun’s energy into food energy.

Detailed explanation-4: -Carbon dioxide in the atmosphere can be fixed by photosynthetic organisms such as plants.

Detailed explanation-5: -While oxygen is necessary for most life on Earth, the majority of Earth’s atmosphere is not oxygen. Earth’s atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases.