The Begining of the End

May 20, 2013

Well its the end of the school year and all of my blogs are due today….. so naturally I’m making this post right this very minuet.

SO for this blog post ill just run through all of the basic info we covered right before the AP bio exam.

or topics for discussion:

Chi Square Test

The Immune system

The Gibbs free Energy equation

The Chi Squared test……. urg this thing is a pain.

So the chi squared test is based off of an equation that look like this


The main use of the Chi squared test is for genetics and confirming Mendelian genetics. So, here’s how it works. In a cross the between Hh and Hh there are four possible allele pair outcomes. HH Hh Hh and hh. the H is dominant so the allele ratio is 3:1. these the ratio replaces value of E in the above equation. We used the equation to measure the data that we gathered from or plants that we were breeding the entire year. so we collected all of our seedlings and separated them in to dominant and recessive. say the total wa 80 seedlings the expected ratio according to Mendel would be 60:20 our observed ratio was 52:28 the chi squared test is about to tell us whether or not our data is close enough to be considered correct. so you set up the problem like this.


The Resulting decimal is then plugged into a degree of freedom chart to determine how accurate the collected data is.

below is Degree of freedom chart.


So What is a degree of freedom? that’s a good question, well when you use the Chi Squared method you sum together a ratio. Above I had only a two-part ratio so you get the degree of freedom by taking the number of sums added together in the equation and subtract one. so above I had two that means I operate in the first degree of freedom. if I was working with a DI-hybrid cross I would have had a 4 part ratio meaning that I would operate in the 3rd degree of freedom. Now you may wonder what is the Degree of freedom for well it determines how accurate your data is. along the top of chart are decimals that pertain to how exact your result is a bench mark is within 5% or .05 so if you go down the .05 column to the 1st degree of freedom you will find 6.314. Now you might be like great another number but if your first decimal is less than the number from the degree of freedom chart congratulations you have successful disproved the null hypothesis. Now I know that sounds super complicated but all it means is that your data fall within the acceptable range of  number to be proven correct. And with that we are finished with the Chi Squared test.THE IMMUNE SYSTEM. if only it made me immune to homework.

The world is filled with deadly things but one thing that is deadly to our every day lives and your date night is the common cold. Viruses are all around us and they attack our body by attaching to a cell with the coded little spikes and using the cell to make more copies of itself to infect the rest of the body.

Now the immune system is designed to combat threats like viruses. the ways in which our bodies combat such threats are classified under two categories. The first is no specific or innate and the specific or adaptive. th innate immune system is constantly in effect it is made up of the layer of our skin our nose hairs the mucus in our nose and throat. The innate immune system is the preventative side of the immune system. The offensive side is only triggered when there are viruses in the body. Now Some important cells  that are a part of the immune system are the macrophages the helper t cells and the killer t cells. When some one is affected the killer t cells jump into the fray and start killing cells in an attempt to destroy the virus before it spreads. The cells that they kill are random and this cause things like sore throats. While the Killer T cell is killing it, the macrophages are cleaning up the mess. Macrophages will eat parts of the virus cells that were destroyed resulting in the locating of a viruses antigen. An antigen is personalized to one virus and when picked up by a macrophages is given to a helper T cell so that A B cell a cell similar to the T cells can mas produce antibodies. these antibodies Locate the virus cells and attach to them marking them for destruction.a and then the Killer T cells and macrophages go about their business destroying what remains of the virus.Finally The Gibbs Free energy equation.

don’t worry this one is less actual math and more just theory in my explanation.

The change in free energy = change in enthalpy – temperature x change in entropy

big ole fancy words and whatnot its hard to understand so let me simplify

The change in free energy: Remaining use-able energy

Change in enthalpy: total energy in a system.

Change in entropy: Energy being used in the system.

Entropy is multiplied by temperature because as the temperature increases so does the energy being used.

So the total energy left for use is equal to the total energy minus the temperature of the system multiplied by the energy being used.

simple right!

Anyway that’s all for this blog post its time for me to turn it in  and finish up my year. As always I hope it was insightful and helpful. good luck biology peeps!


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