Identify the independent variable. Prior to the mid-1800s, people believed that
ID: 47292 • Letter: I
Question
Identify the independent variable.
Prior to the mid-1800s, people believed that bacteria appeared in the food through spontaneous generation, which held that living organisms arose spontaneously from non-living matter (such as dust). In 1862, Louis Pasteur questioned whether spontaneous generation was possible. He boiled several batches of broth (growth medium) to kill any existing bacteria. After boiling, all batches of broth were then exposed to the air, but some of the boiled batches of broth were protected by filters or long, twisting tubes to prevent dust and other particles from passing through to the broth. His results showed that a variety of organisms grew in the broths that were not protected by filters and tubes, but nothing grew in the broths that were protected by filters or tubes. Based on this description, what is the independent variable?
1) Whether there is any growth of microorganisms.
2) How long the broth is boiled.
3) How long the broth was exposed to air.
4) Spontaneous generation.
5) Whether or not the broth was exposed to air.
I was thinking the independent variable had something to do with whether the broth was protected by filters/twisty tubes or not.
Explanation / Answer
Answer:
5) Whether or not the broth was exposed to air.
The independent variable is the factor that is changed during the experiment. I an experiment, there will only one idependent variable.
From the above experiment, the scientist have exposed the broth to the air, and also they kept filters to prevent the passage of bacteria, so the this can be the independent variable.
The growth of the micropragnism is observed latter in the broth with filters and with filter, this is an dependent variable.