1 Lab Online –Summer 2020 Lab 4: Biological Molecules At–Home Experiment Iodine Test and Lipid Test Instructions Items needed:

•Oil  Vegetable, canola, olive, etc.Just clean and in liquid form

•Water Can be bottled or from the faucet.

•Sugar or Sugar Substitute Whatever type of sugar, sugar substitute, or honey you have on hand.Mix at least a teaspoon with ¼cup warm water.Make sure granules dissolve.

•Iodine  Small bottle,can be found in first aid section at most stores. This is safe to get on your skin, it’s just a disinfectant, but it will stain skin, clothes plastic dishes, white counters, etc.

•1–2 tea spoons of flour, cornstarch, corn meal, or dry instant mashed potatoes, or all if you’re feeling froggy Mix 1–2table spoons of dry substance with ¼cup of warm water.

•Small containers or bowls, at least 6.They don’t have to be clear, but you need to be able to see into them well to see color changes.Glass will work best to prevent staining from the iodine.

•A small piece of food that you pick from your kitchen. This can be a couple pieces of cereal, small piece of cheese, chips, a piece of banana, any food item really.

▪If it’s a dry food, crunch it up well and mix it with 2–3 tablespoons of water.

▪If it’s a fruit or vegetable, you don’t need to mash it up or add water, just make sure it’s peeled showing the interior of the fruit or vegetable.

•1 piece of construction paper, piece of brown paper bag, or cardboard cut into two pieces.These two pieces can be kind of smaller if you can’t find a big piece, 2 inches by 2 inches is really all you need. Lipid Test–Tests for lipids in a liquid.Wet look after drying is a positive for lipids.If the drop dries back to the original color, then it is negative.

Procedure:

1.Get your two pieces of cardboard, construction paper, or brown paper bag.

2.Place a place under each to prevent oil getting on anything.

3.Place a drop of water on one.

4.Place a drop of oil on the other.

5.Let these sit until your drop of water is dry.

6.Which liquid was positive for lipids? You can also try this with salad dressings, marinades, etc.

You will not write a lab report over the lipid test but there will be questions on your Lab 4 Quiz pertaining to this portion and your results.

 1 Lab Online –Summer 2020 Iodine Test–Tests for starch which is a polysaccharide. Positive–produces and blue–purple–black color.

Negative–Liquid remains yellow or rusty brown (the color of the Iodine)

Create a table listing all the things you are going to test in the iodine test. This can just be drawn right now then created in word later.List your thoughts, which items do you think will produce a color change? Which do you think won’t produce a color change? What does the color change mean? Why do you assume what you doabout each item? Include your responses in your lab report, even if you were wrong or surprised. Hypothesis: If…then statement. Remember, you want to know which items are positive for polysaccharides.

Be sure to avoid contamination, don’t mix your oil and water with the same tool you used to mix cornstarch and water for example. This could impact your results.

Procedure:

1.Cover the bottom of the bowl or glass with oil, only enough to cover the bottom is needed.

2.Cover the bottom of the bowl or glass with water, same as above.

3.Cover the bottom of the bowl or glass with 50% water and 50% oil, same as above.

4.Cover the bottom of the bowl or glass with sugar/sugar substitute and water mixture.

5.Cover the bottom of the bowl or glass with the flour/cornstarch/cornmeal/potato flake mixture. a.If you want to try multiple of these just do the same and add another bowl with the same steps as above. b.Tip: if using potato flakes, let them sit and soak in the water for at least 10 minutes before adding iodine.

6.Place the random food item you picked from your kitchen in a bowl.

7.Place 2–5 drops of iodine in each bowl, recording your observations as you go. 8.Write your lab report over the experiment you just performed using your experience, data, and what you know about carbohydrates.Pictures of your experiment are always welcome in a lab report!When you are done, using your own knowledge of your sink, liquids can be washed down the sink with no staining if you rinse the sink well immediately. Large pieces are safe to throw away regularly