Glencoe Life Science

Unit 2: From Bacteria to Plants




Do you like broccoli and cauliflower? Do you eat carrots and peas? Perhaps you drink orange or grapefruit juice for breakfast every day, or eat an apple at lunchtime. Fruits and vegetables such as these are essential to a healthy diet, yet many people do not eat enough of these natural foods. There is mounting evidence that eating a well-rounded diet, consisting of several servings of fruits and vegetables every day, can reduce the effects of aging, and help to prevent diseases such as cancer, diabetes, and heart disease. The chemicals that occur naturally in plants, such as fruits and vegetables, are called phytochemicals. You may have seen television commercials that discuss the health benefits of taking supplements that contain lutein and capsaicin, two types of phytochemicals. What are phytochemicals exactly? What foods contain important phytochemicals? Do you have to eat broccoli to obtain its healthful phytochemicals, or can you benefit equally by taking a pill that contains those phytochemicals? In this WebQuest, you’ll learn the answers to these questions as you explore the nature of phytochemicals.



Your job in this WebQuest is to learn all about the phytochemicals found in fruits and vegetables, and the benefits of eating these foods as part of a balanced diet. You will discover what phytochemicals have been studied scientifically, and what these research studies have discovered. You will learn about the different phytochemicals that can be found in natural foods, and the health benefits of each type. You will fill in a table in which ten different foods or groups of foods are listed. For each food or group of food, you will list the important phytochemical(s) each contains, and the health benefits of eating that food. Finally, you will answer a few questions about phytochemicals to demonstrate what you have learned in your Internet research.



Look at the web sites given here to find the information that will enable you to complete your table on phytochemicals and answer a few questions.

  • Phytochemicals and Cardiovascular Disease. Go to this site by the American Heart Association to find out what phytochemicals are being used to treat heart disease. The Association recommends that people eat more fruits and vegetables to obtain the optimum benefits from a healthy diet.
  • The Phytochemical Collection. Visit this site by Florida State University for a brief history of the importance of including fruits and vegetables in the diet. Scroll down to see a listing of phytochemicals that have been shown scientifically to combat diseases.



1 class period for research, filling in the table, and answering a few questions.



Now that you have completed your research on phytochemicals, prepare a table like the one below with the information that you have gathered about the foods listed. For each food or group of foods, list the phytochemicals they contain, then list the health benefits of the phytochemicals or the diseases that those phytochemicals can be used to treat. You will need to look at all of the web sites listed in order to complete the table. Once the table has been filled in, answer the questions that follow.

Table 1. Phytochemicals and a Healthy Diet

FoodPhytochemical(s) Health Benefit/Disease Treated
Broccoli, cauliflower   


Citrus fruits  
Tomatoes, peppers  
Grapes, berries, cherries, apples, cantaloupes  
Soybeans, beans, oats, seeds, whole grains, brown rice  
Licorice root, green tea  



Questions about Phytochemicals and a Healthy Diet

  1. Scientific studies have shown that phytochemicals are associated with prevention and treatment of four leading causes of death in the United States. What are they?
  2. Many vegetables are prepared by cooking, such as broccoli and cauliflower. Does cooking destroy the phytochemicals found in these foods?
  3. Health food stores already sell some phytochemicals in pill form. Does taking phytochemicals in a pill form provide the same health benefits as eating the food itself?



In the process of completing this WebQuest, you’ve become informed about the importance of including fruits and vegetables in your diet. You have learned what phytochemicals are and what foods contain important phytochemicals. You have developed critical thinking skills as you explored the health benefits of phytochemicals. To protect yourself from developing diseases such as cancer and cardiovascular disease in the future, what changes should you make in your diet today?



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