1.carbon 2oxygen 3.nitrogen is an element found in all organic molecules. during respiration, animals excrete it as a gas known as . 1 nh4 2 o2 3. co2

1st=Carbon

2nd=CO2

Hope it's right!

1. Carbon

2. CO2

Explanation:

1. All living things are made of inorganic molecules mainly carbon and hydrogen. These two elements form the backbone of hydrocarbons which are considered as the building block of living things

2.During respiration in living beings (animals and human beings), the oxidation of carbohydrates takes place  in which glucose is break down into carbon dioxide and water.  

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy