Section 2: Humans use plants and plant products in many different ways.

Key Ideas   Unit Checklist

  Unit B: Section 2 - Introduction

Figure B.S.2.1 – Sailors on long ocean trips suffered from a disease called scurvy.
Figure B.S.2.2 – Scurvy causes bleeding gums, which leads to teeth falling out.

Scurvy and Vitamin C

Scurvy is a disease that affected sailors who spent many months at sea eating only dried and salted foods. Scurvy causes tiredness, muscle aches, and rashes. Scurvy also causes teeth to fall out and old scars to start to bleed again.

In the past, ships did not have cold fridges, so fresh fruits and vegetables on board spoiled quickly. Sailors ate salted and dried food that kept for months. In the 1700s, James Lind, a doctor on a Scottish ship, discovered that sailors who ate citrus fruits such as oranges, lemons, or limes healed from scurvy.

In the 1800s, the British Navy made a rule that all sailors had to drink lime juice everyday to prevent scurvy. As a result, British sailors became nicknamed “limeys”.

We now know that scurvy is caused by a lack of Vitamin C in a person’s diet. Vitamin C is found in citrus fruits as well as in many other fresh fruits and vegetables.

Figure B.S.2.3 – Vitamin C is found naturally in many fruits and vegetables.
Figure B.S.2.4 – Sometimes people take supplement pills to be sure they receive enough Vitamin C.

 Watch More

What are Vitamins?

Vitamin C is not the only vitamin that  our bodies needs. Watch this video to learn more about vitamins and how they help our bodies.


Various Vitamins

Eating a balanced diet with lots of vegetables and fruit is important so that the body receives all the vitamins it needs to be healthy. For example, Vitamin A helps eyesight. Vitamin K helps to stop bleeding from a cut. Vitamin E helps gets rid of harmful substances in the body.

The human body can make a few vitamins, but most of our vitamins come from plants and plant-eating animals. The only vitamin that the human body needs that cannot be obtained from plants is Vitamin B12. Vegetarians or vegans who choose not to eat food that comes from animals should take supplements or eat grains with Vitamin B12.
Figure B.S.2.5 – Vitamin A is found in colourful vegetables.

Figure B.S.2.6 – Vitamin K is found in green vegetables such as broccoli, spinach, and kale.
Figure B.S.2.7 – Vitamin E is found in nuts.

 Watch More

Do Carrots Help Your Eyes?

Has anyone told you to eat carrots because they’re good for your eyes? Watch this video to learn about the vitamins in carrots.

  Words to Think About:

Check out the word cloud below. It pictures the important words that you are going to learn in this section. Watch for these words, and combinations of these words, as you read. When you see them highlighted, you can click on them to learn more about what the word means. You can also visit the course glossary and read definitions for all of these words.
Lessons in This Section

Lesson B7:  Plant Adaptations
Key Question – What features of plants help them survive in various environments?

Lesson B8:  The Role and Use of Plants
Key Question – In what ways do people rely on plants?

Lesson B9:  Forestry: An Important Alberta Industry
Key Question – Why is taking care of Alberta’s forests important?
Reading and Materials for This Section

Science in Action 7
Reading: Pages 116–137

Materials Lists for Unit:

  Try It!

How Much Vitamin C?

Try this simple experiment to see which type of juice contains the most Vitamin C.
 
A mixture of iodine and starch changes colour from dark blue to colourless when it is mixed with Vitamin C. The more Vitamin C you add, the faster you will see a colour change.

Materials:

  • cornstarch
  • iodine
  • water
  • spoon
  • measuring spoons
  • measuring cups
  • 3 coffee filters
  • plastic funnel
  • 6 glass cups
  • 5 eyedroppers
  • white paper
  • orange juice
  • apple juice
  • lemon juice
  • lime juice
Iodine stains skin, clothing, and any materials it comes into contact with.

Instructions:

  1. Mix 2 tablespoons of cornstarch with 2 cups of water.

  2. Put 3 coffee filters into a plastic funnel. Place the funnel over a clean glass cup.

  3. Pour the cornstarch and water mixture into the funnel and through the coffee filters and into the glass cup. The water in the cup should be a little cloudy.

  4. Use an eyedropper to add iodine to the cornstarch water drop by drop. Stir with a clean spoon. Add drops of iodine until the mixture just turns dark blue. Be careful not to add extra iodine.

  5. Put ¼ cup of iodine/cornstarch mixture into each of four clean glass cups. 

  6. Place each glass cup on a white sheet of paper.

  7. Fill a clean eyedropper with orange juice. Add the orange juice one drop at a time to one of the iodine/cornstarch cups. Swirl the cup slowly as you add orange juice.

  8. Count how many drops of orange juice you add until the iodine/cornstarch mixture turns from blue to colourless and stays colourless when stirred.

  9. Repeat steps 7 and 8 for apple juice, lemon juice, and lime juice.

  10. Record your results in a table such as this:


Questions:

Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.

Depending on what brand of juice you used, you probably found that orange juice or lemon juice contained the most Vitamin C. The juice that contained the most Vitamin C took the least amount of drops to change the colour of the iodine and starch mixture.