Experiments can always go "wrong", but they are important because they provide evidence that maybe is not the fertilizer the variable that is influencing plant growth. After this you could change the experiment taking into account new variables such as pH, amount of water or sunlight etc.
Darwin called the ability of an organism to survive and reproduce in its environment fitness. Some organisms were fit to do all of these things, whereas others were not.
The hydroponics root system to grow is that they use the same method as the soil root but the root volume for hydroponics is highly restricted and they don't need to use too much energy to grow.
