We have done some extensive experiments on taste buds: how they are categorized, what tastes they recognize, and we have even mapped their location on your tongue. But we haven’t yet mentioned this fact: not all people can taste the same flavors!


So today we will check to see if you have a dominant or recessive gene for a distinct genetic characteristic. We’ll do this by testing your reaction to the taste of a chemical called phenylthiocarbamide (or PTC, for short). The interesting thing about PTC is that some people can taste it – and generally have a very adverse reaction. However, some people can’t taste it at all.


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Digestion starts in your mouth as soon as you start to chew. Your saliva is full of enzymes. They are a kind of chemical key that unlock chains of protein, fat, and starch molecules. Enzymes break these chains down into smaller molecules like sugars and amino acids.


In this experiment, we will examine how the enzymes in your mouth help to break down the starch in a cracker. You will test the cracker to confirm starch content, then put it in your mouth and chew it for a long time in order to really let the enzymes do their job. Finally you will test the cracker for starch content and see what has happened as a result of your chewing.


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The tongue has an ingenious design. Receptors responsible for getting information are separate and compartmentalized. So, different areas on the tongue actually have receptors for different types of tastes. This helps us to separate and enjoy the distinct flavors. In this experiment, you will be locating the receptors for sweet, sour, salty, and bitter on the tongue’s surface.


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Did you know that your tongue can taste about 10,000 unique flavors? Our tongues take an organized approach to flavor classification by dividing tastes into the four basic categories of sweet, sour, salty, and bitter.


For this experiment, you will need a brave partner! They will be blindfolded and will be attempting to guess foods. Relying only on their sense of taste, they will try to determine what kind of foods you are giving them.


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What is happening when we feel hungry? Or when we feel thirsty?

What we are feeling are  hormones signaling our brain that we need food or water.

Hormones play a large role in our digestion process. They help maintain homeostasis by stimulating appetite, thirst, as well as many, many other bodily functions.

Digestion is the process of food (and drink) being broken down and absorbed. The mouth begins the digestion by breaking down food mechanically and chemically. Protein is digested in the stomach. The small intestine finishes the chemical digestion and absorption of food. The large intestine absorbs excess water from the waste and finally passes it through the anus.



What happens to those meals when they enter our mouths? There are the main things that happen:

  1. Digestion: Digestion involves the breakdown of what we consume into nutrients. The first step is mechanical digestion—chewing. After we mechanically break down the food with our teeth, we begin chemical digestion. Chemical digestion breaks down what we eat and drink chemically. Chemical digestion is mostly accomplished by proteins called enzymes.
  2. Absorption: After we’ve broken down the nutrients we need, we absorb them into our body. This step is called absorption.
  3. Elimination: Lastly, we excrete solid and liquid waste.
Digestion begins in the mouth. In the mouth, the teeth digest food mechanically, and the saliva digests starches chemically.  Enzymes are catalysts that make chemical reactions go faster. They are found at every important step of digestion. Amylase is found in our saliva, and it helps breaks down bread-like things (starches) into smaller sugar molecules. Pepsin helps us digest protein in our stomachs. Pancreatic lipase breaks down fats.

After the mouth, the food travels to the stomach through a narrow tube called the esophagus. The esophagus moves the ball of chewed and partially digested food into the stomach. Food is moved through the tube via muscle contractions. The muscle contractions start in the esophagus and end in the anus, moving in a wave called peristalsis. Peristalsis is the name of the movement of the muscle contractions moving the food through the tube.

Once in the stomach, the food is further chemically digested. The protein is digested with the enzyme pepsin. Pepsin, along with other chemicals such as hydrochloric acid (HCl) chemically digest the food. Water, salts, and simple sugars are absorbed through the walls of the stomach. The rest of the nutrients are absorbed after exiting the stomach.

The small intestine, about 7 ft long, has three parts. The large intestine takes the liquid waste from the small intestine, absorbs the excess water, and excretes the solid was through the anus. The large intestine is home to trillions of helpful bacteria. Although we often think of bacteria as harmful, most bacteria is helpful. The bacteria in our small intestines helps us digest food, and we provide the bacteria a place to live. Among other functions, the bacteria in our large intestines produce vitamins B12 and K, as well as break down poisons.

The liver is essential to digestion, and life. The liver detoxifies the blood, maintains the glucose balance, synthesizes proteins, and produces many chemicals needed for digestion.

Getting the right nutrients and getting fiber in your diet is extremely important. The nutrients keep your system running well, while fiber helps to move waste through your digestive system. If you do not get enough fiber you may become constipated; unable to pass waste.

Maintaining a healthy digestive system means a.) maintaining a healthy diet, and b.) taking care of any illnesses, allergies, or intolerances which arise.  

Eating and drinking are essential parts of our life. Part of maintaining a healthy lifestyle is making sure to eat and drink the right quantities of the six essential nutrients. Those nutrients are: protein, carbohydrates, lipids, vitamins, minerals, and water.




Does it mean to eat all vegetables? Does it mean to eat only meat? No. A healthy diet is a balanced diet. This is what MyPlate demonstrates. A balanced diet means getting the right amounts of nutrients. MyPlate guidelines are recommendations from the United States Department of Agriculture (USDA). Since 1958 the USDA has recommended a balanced diet in the form of the food pyramid. However, the pyramid proved to be too complicated for most Americans to efficiently use to create diets. In response, the USDA simplified its recommendations in 2011 into the MyPlate format.




We already know what a diet is—the sum of food and drink consumed. Now, what does it mean to have a healthy diet?




The specific advice of the USDA is:


  • Balance calorie intake.
  • Enjoy your food, but eat less.
  • Avoid oversized portions.
  • Eat certain foods.
  • Make half your plate fruit and vegetables.
  • Make at least half your grains whole grains.
  • Switch to fat-free or low fat (1%) milk.
  • Eat certain foods in moderation.
  • Compare sodium in foods like sodium, bread, and frozen meals—and choose the foods with lower numbers.
  • Drink water instead of sugary drinks.