Monday, May 7, 2012

Scribe Post 5/7

Hi Class!!!

In class today we-
  • Collected lab 55 (frog lab)
  •  Stamp nutrient pre-lab
  • Went over class data from calorimetry lab
  • went over nutrient lab pre-lab 
  • Practice quiz
  • Design a quiz due TOMORROW!
  • Finish calorimetry lab 
  • Test Thursday, Study!!!
*** Just a reminder about the design a quiz! It should be 20 questions. the 

questions should be thought provoking and at an honors course level. Make sure that you use variations of questions like fill in the blank, multiple choice, and matching. Add at least one diagram in it. 

For a long time in class today we reviewed the calorimetry lab. Everyone was a little bit confused of how to find answers to how find energy content in a food. 

Remember these things, the basic formula for solving the energy content in a food is

Energy content of food = Energy gained by water / The change in the mass of food 

Before you can do that formula, you have to be able to find the energy gained by water. This is the formula for how to solve it.

Energy gained by water = (mass of water) x (Changet of water) x (4.18 J/g C)

Before you can calculate the energy of your food you have to divide your answer by 100. this is because it is in joules and needs to be converted into kilojoules.

Practice that and make sure you know how to do it because you need to understand it for the test!

Next we went over the pre-lab for the nutrient lab!

We will be testing foods for protein, simple sugars, starch, and lipids

We will do these by a variety of tests.. these test are.......

Iodine Test-
Tests for starch. this test is when you use Lugol's iodine solution. this yellow-brown solution will mix with the food. if there is starch present it will turn blue-black in color.  

Benedict's Test - 
Tests for simple sugars. It is blue in color, but when there is sugar it will change to green yellow or brick red.

Biuret Test-
Tests for proteins. When you add the solutions to food and stir, the mixture will either stay blue for negative results or turn pink-purple for positive results. 

Brown Paper Bag Test- (sounds dangerous)
Basically you leave your food on the brown paper bag and if it leaves an oily smeary translucent smear it is positive for lipids. If it does not, then it is negative..

Also remember to bring your own food to test!

Have a good night!



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