Observations and Macromolecules
Observations and Macromolecules
For this week’s lab, you are going to complete two shorter lab activities. You will need the following for these labs:
Three different fruits– they can be any type of fruit, just three different kinds. You ‘ll need to be able to touch and measure these as well as cut into them. You can use three different types of vegetables if you’d like (but don’t mix fruits and veggies)
Tape measure (use the printed one from last week if needed)
A blank sheet of paper
Five different food items that have nutrition labels
Part 1 – Observations
Humans, like most animals, have five senses: sight, touch, smell, taste and hearing. Most of us have good vision (or at least correctable vision), yet we cannot see the ultraviolet light waves that some insects can. Bats and dolphins have ultrasonic hearing that we lack. Although we have just a fair sense of taste, smell, sight, and touch relative to many others, the sum of our senses is how we gather information about the world we inhabit, and we gather a tremendous amount of information every day. Much of this information we save in short or long-term memory.
The science of biology starts with observations. Questions arise based on these observations, which in turn lead to hypotheses or possible explanations for the observed phenomena. It is therefore very important that your observations are comprehensive and accurate.
In today’s exercise, you are going to make some observations and record what you see, touch, taste, hear and smell. You are going to pretend that you are an explorer like David Douglas or Alfred Wallace. You need to record complete, accurate descriptions of the organisms you find so that other scientists may identify them.
Take one of the pieces of fruit you have collected and observe it. Try to imagine you are an explorer and the local people in the area brought you this object and indicated that it was edible. You have never seen this kind of fruit before and you do not know the its name, so you cannot use the word in your description.
List all of your observations about this fruit below. Your report should include observations based on all your senses: sight, touch, smell, taste and hearing. Do not try to speculate about what the fruit is or where it came from. You should describe just what your senses detect as completely and precisely as possible.
Use the knife to cut your fruit so that you can observe its interior structure. Add this information to your report, Type to expand the columns and rows as necessary. Make whatever measurements you think are appropriate and useful. Always use metric units.
|Description of Fruit #1|
Observe the two other fruits and record your findings. Look at how these fruits differ from each other. Think in terms of size, shape, color, texture, taste, interior structure, number of seeds, etc. Pick your own characteristics for the column labeled “other”. Be sure to complete this column.
Double check that you have included measurements (in metric).
Part 2 Macromolecules in Food
In this lab you will be looking at the nutrition labels of at least 5 food items. Most packaged food will have a label, but whole foods (like carrots, or potatoes) don’t. If you really want to use a whole food – you can, but you’ll need to look up the nutrition label at a website like this one: http://nutritiondata.self.com/ It’s best to look at a variety of labels, don’t pick things you think are ‘healthy’ or not. Just a variety.
|Name of food item|
Directions: Examine the “Nutrition Facts” labels of a variety of food items. You need to select five different types of food. Try to get some that contain fats, protein and carbohydrates. Don’t use things like water, or candy which will have very simple labels.
Write down the information for each food item in the chart below then answer the questions in complete sentences.
|Name of Food Item||Serving Size (in g)|
|Total number of calories|
|Total Fat (lipids in g)|
|Total Carbohydrates (in g)|
|Total Protein (in g)|
Look carefully at the Carbohydrates in one or more of the labels. You will see a listing for “Total Carbohydrate”, ‘Dietary Fiber” and “Sugars”. Review the material in Chapter 2 if needed and answer the following questions.
- We know that carbohydrates typically fall into three size classes: monosaccharides, disaccharides and poly saccharides.
- Which of these types do “sugars” fall into?
- Which of these types do “Dietary Fiber” fall into?
- Using the sample label from above, there are 6g of Fiber, and 6g of Sugars, but 26g of Carbohydrates. What type of carbohydrate make up the ‘missing’ 14g of carbohydrate?
- What is the main difference, in terms of nutrition, between fiber, which is listed separately, and the rest of the carbohydrates?
Find a label that lists each of the types of fats (use this one if needed) and look carefully at the Fats in one or more of the labels. You will see a listing for “Total Fat”, ‘Saturated Fat” and “Trans Fat”. Review the material in Chapter 2 if needed and answer the following questions.
- Which foods contained the most lipids (fat) per serving?
- Does the Total fat equal the Trans fats + saturated fat?
- If not, what is the other type of fat?
- What is the difference between a saturated fat and an unsaturated fat? Draw a picture that illustrates the difference
- Are Trans fats saturated or unsaturated? (This is a tricky question!)
- There is no recommended % Daily Value for trans fats. Why do you think that is and what is the recommendation from Dietary trans fats in our diets?
Find a label that has some Protein AND contains no animal products (use this one from garbanzo beans if needed).
- Which foods contained the most protein per serving?
- How many grams of Protein are in 1 serving?
- Look at the ingredient list (should be somewhere on the label) and look to see if this product contains any animal products (egg, milk, butter, gelatin etc). If there are no animal products, where does the protein come from?
Food labels list the number of calories in a food. Calories come from burning macromolecules in our cells to make ATP (a form of chemical energy). Look at the bottom of the label  and answer the following questions.
- Which of the macromolecule provides the most calories per gram?
- You can calculate the “calorie density” of a food by dividing the total calories per serving by the weight of 1 serving. Do this math on your 5 labels and record your answers here:
|Name of Food Item||Calorie density (cal/g)|
- Which food had the highest calorie density?
- Why do you think this food is calorie dense?