Exactly one pound of bread dough is placed in a baking tin. the dough is cooked in an oven at 350°f, releasing a wonderful aroma of freshly baked bread during the cooking process. is the mass of the baked loaf greater than, less than, or the same as the one pound of original dough?

The mass of the baked loaf will be less than the dough.

Explanation: When heat is applied to food substance or products like the one pound the substance or material gains a higher temperature, the increase in temperature causes moisture inherent or added to the product in this case the one pound dough to be lost, the one pound dough prepared at room temperature, once it is placed inside the oven at 350 degrees Fahrenheit it will lose moisture  in the form of vapor to the environment as noticed in the aroma, the moisture lost will eventually reduce it mass/weight (kilograms or grams) by some percentage or quantities(kilograms or grams)

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 =