14) Below are diagrams of three different species distribution patterns, random,

Question

14) Below are diagrams of three different species distribution patterns, random, clustered, and uniform.

The relationship of variance and mean informs researchers about the spread of data. If a researcher calculates the mean abundance per unit area of a species, and then calculates the variance, the relationship between mean and variance will reflect the distribution pattern.

Which distribution pattern pictured below will have variance less than the mean?

QUESTION 1

You're an undercover biological weapons agent who has been given an unknown liquid - you suspect that it is just sugar water (because you drank some by accident - you know you're not supposed to have food or drink in the lab, but you do it all the time, and it tasted sweet - plus you didn't die!) One of the tests you need to run is to see if it contains protein (remember, foreign proteins can cause severe immune responses which can be a powerful biological weapon). You set up 3 test tubes each with 10mL of the following: distilled water, gelatin solution and the unknown.

The distilled water is clear, the gelatin solution is clear with a beige tint, and the unknown is clear.

You use Biuret's Reagent - a dark blue dye which will turn a liquid sample purple in the presence of protein.

When Biuret's Reagen is added to the unknown, predict what color you expect it to become if the unknown is just sugar water: [a] (no change | blue | purple).  

3 points   

QUESTION 2

You included both a positive and negative control for this experiment. The gelatin is the [c] control.

3 points   

QUESTION 3

If the positive control turns blue, it means:

there is no protein present

this control is no good - need to troubleshoot and perform the experiment again

there is protein present

this control is doing exactly what its supposed to do - you can have confidence that the results of the unknown will be accurate

Explanation / Answer

There are three distribution patterns, present in the diagram. They are random, clustered and uniform. If a researcher calculates the mean abundance per unit area of a species, and then calculates the variance, the relationship between mean and variance will reflect the distribution pattern. So, the uniform pattern will have variance less than the mean. As, the pattern is uniform, there is less variance, as deviation from the mean is less.

When Biuret's Reagent is added to the unknown, which is just a sugar water, the colour will be purple. Because Biuret detects the presence of protein and forms violet colour. In sugar water, there is no protein, thus will not form any purple colour. Rather, because of it's own copper (II) ion, it forms blue colour.

If the positive control turns blue, it means this control is no good-need to troubleshoot and perform the experiment again. Because, as it is a positive control, it should have protein content and should form purple colour. As, it shows blue colour, that means, no protein is present and blue colour is because of the copper ion of the chemical.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.