University of Arkansas - AgriScience Project

AGRISCIENCE EXERCISE

PLANT SCIENCE & BIOTECHNOLOGY

Key Concept: Plant Vegetative Structures

Sub-Concept: Roots

Agricultural Context: Different types of plants and plant parts are used for agricultural purposes.

Exercise: Starch Storage in Roots

Applied Principle: Some types of roots store food for the plant

Goals:

  1. Identify 3 types of plants which store food in their roots.
  2. Explain how to determine whether starch is present in a root sample.
  3. Describe the functions of the parts of a root.


Materials:



References: Trudeau, M. (1994). Plant Morphology and Taxonomy. Ithaca, NY: Cornell I.M.S.

Teacher Preparation Notes:



Procedures for Conducting the Activity:

1. Divide the class into pairs of students, and provide each with a data sheet and the necessary materials for this exercise.

2. Instruct the students to complete the activity as directed on their data sheets. You may wish to monitor their progress as they work; however, it is suggested that the students be left to follow the instructions and complete the activity on their own.

3. Once all groups have completed the exercise, discuss the answers to the discussion questions as a class. Be sure to make note of the practical agricultural applications of the principles demonstrated.

AGRISCIENCE EXERCISE

- Starch Storage in Roots -

Student Data/Instruction Sheet

1. Your instructor should provide your group with the following materials:



2. Use the razor blade or knife to cut a very thin slice of each root.

[NOTE: Exercise extreme caution when using the knife!!]

3. Place each slice in a separate petri dish.

4. Place one dropper full of iodine solution on each slice, making sure that iodine remains on each slice.

5. Over the next 15 minutes, observe the slices, examining them with a hand lens. Looking for blue-black areas to emerge, which indicates the presence of starch. Note the areas of the slice which show the presence of starch, and how long it takes for these to become apparent. Record your observations on the chart below:

Time

Carrot

Turnip

Radish

5 minutes
10 minutes
15 minutes




6. Draw and label a picture of each root slice on the back of this sheet, indicating where you found evidence of starch. (You should include the epidermis, cortex, xylem, and phloem.)



7. Answer the following questions, and be prepared to discuss the results in class:

a. Why is it useful to humans for roots to store food?











b. When you eat a carrot, you can tell a difference between the outer, darker ring and the center parts. What are the differences? Why do you think this is so?











c. What are the 3 main functions of roots?













d. What does this exercise demonstrate about the different cell types and their functions within a root?



















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