What are controls in biology?

Question

What are controls in biology experiments? How do you they give you information? This is soooooooo confusing?

Answer 1

There are many different kinds of controls, depending on what kind of biology you are doing, so there is no simple answer.

A positive control is an experiment where you expect everything to work. For example, in PCR a positive control would be a reaction where you've added the known template target. It's there to make sure you did everything correctly.

A negative control is an experiment where you would expect no results. For example, in PCR a negative control would be a reaction where you've added no template, only water. It's there to make sure that if you did get results, it's not the result of a mistake in experimental procedure like contamination.

Answer 2

When you are doing biology experiments you need to show that the technique you are using is really working (that is the information you get from controls). The proves you use to show this are called controls.

For example, if I am trying to evaluate whether the protein levels of a gene in a type of cell is down regulated (or up regulated or no change) under certain conditions, I will perform a western blot.

Let's say we see no change on the protein levels of the cell under two different conditions in the western blot. Does this mean that there is no change in the protein levels? how can I tell that this is what is really happening and it is not a problem of specificity of the antibody? To answer this, you use controls. I need to show that the antibody is working properly. For that I will use as a positive control a recombinant protein and as a negative control lysate from a cell that was knock out for that gene (that is it won't have that protein) so in the western I will prove that the antibody in fact can recognize the protein (positive control) and doesn't recognize any other protein different from that (negative control)

Positive controls show that your technique can evaluate whatever you are evaluating in your experiment and negative controls show that is only specific for whatever you are evaluating.

Answer 3

In biology, controls are usually a groups of organisms that you treat normally, so you can compare them with a group of test organisms that are undergoing some sort of experimental treatment. For example, lets say you want test the hypothesis that wild rabbits are most active in twilight. To set up the experiment, you might keep one group of rabbits entirely in natural light (as a control) and then keep another group at a constant light level simulating twilight. Next, you might film the rabbits to observe their activity.

If the hypothesis is correct, then the rabbits kept at twilight conditions should be active for a much longer part of the day. The hypothesis would not be correct if there was no difference in the activity levels between the control group and the rabbits kept in the twilight conditions. Without the control group, you have no way of knowing if the the experiment has any effect.

Answer 4

controls in biology refer to a comparison to the experiment. you would have a control to investigate if the experiment is effective, it provides a base measurement to whihc you can then compare the results of your study to. for example, if you were studying the effect of light on the rate of photosynthesis you would have one plant which you would place in the light everyday and after experiment is complete you would measure the rate of photosynthesis. the control of this experiment would be a plant that is kept out of the light for the specified length of time of the experiment, and results from this would be compared to the experiment plant, allowing you to make a decision of whether light affects photosynthesis rate.