How does conduction differ from convection?

for online classes : Conduction warms the atmosphere as fast-moving molecules come into contact with lower-energy molecules until all molecules are moving at about the same rate. As the atmosphere warms, molecules move apart. As the heated air flows, heat is transferred by convection from warm, low-pressure air to cooler, high-pressure air.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =