“The Birth of the Apple Tree”

 

Topic:  Germination of the Apple Seed

 

Intended Grade: 7th or 8th

 

Purpose:  The broad goal of this experiment is to teach students the distinct difference between a dormant apple seed and a seed that has germinated.  Students will learn about the process of cell division, as well as how and why the seed gives way to roots and the shoot.  The germination process is an important concept for students to grasp since it initiates the growth of the tree.  There are a set of ideal conditions for growth that can be manipulated by farmers, making plant development an important aspect of environmental management and IPM.  The concepts incorporated in this activity are important because they meet many state and national curriculum standards.  Some of these standards include the unity of cells in nature and the way in which plants use sunlight and water to synthesize carbohydrates for growth and repair.

 

Objectives:  Upon the completion of this lesson, students will be able to:

-         Describe the process of germination and the conditions required for germination to take place.

-         Label and/or identify various tissues in both a dormant seed and a germinating seed using a stereoscope.

-         Make drawings showing the physical differences between the dormant and germinated seed.

 

Background Knowledge Needed:

By Students and Teacher: 

            Students should be familiar with two important life cycle stages of a seed, dormancy and germination.  Dormancy refers to a phase where the seed has an extremely slow metabolic rate and is not growing.  Inside the protective coating of the seed is an embryonic root system and shoot waiting for the right conditions to begin the division process.  Students should know that water is the most crucial resource for beginning the processes of cell division.  Germination is the process of cell division.  Under ideal conditions specifically, the presence of oxygen, an adequate water supply, favorable temperature, and soil pH, the cells protected within the seed coat will begin to divide.  Students may not know this originally; it can be discussed as an introduction to the lesson. 

Two other important concepts students should be familiar with are growth and development.  These are irreversible processes that will continue as long as conditions are favorable.  The rate at which an apple tree develops plays a major role in the timing and application of pesticides.  This will play a larger role later in the unit but the methods regarding pest management are important in every phase of apple tree growth.

 

Materials Needed: 

By Teacher:

-         Question/lab sheet (see attached)

-         Overheads of dormant and germinating seeds

 

 

By Students:

-         Dormant apple seeds

-         Germinating apple seeds (see preparation for experience section)

-         Cutting utensils

-         Stereoscope

-         Drawing utensils

 

Grouping:  Pair students into lab groups, a group of three is acceptable. 

 

Preparation for Experience:  It takes a dormant apple seed about 6 weeks to germinate in the presence of water.  Place about 100 apple seeds in a wet paper towel and then seal them in a zip lock bag.  This bag should be kept in the refrigerator.  Under these conditions the seeds should germinate enough to where the students can see the shoot and root system emerging from the seed coat.  Organize the lab into the needed amount of stations for each group. At each station place a stereoscope, cutting utensils, drawing utensils, blank paper, and both dormant and germinating seeds.  Now the students will be ready to begin their observations and drawing.

 

Outline of Experience:

Introduction:  Access what students already know by some simple questioning:  What makes a seed sprout?  Why doesn’t a seed grow in the winter?  Why do planters and growers begin monitoring the weather in the early spring?  Let the students pose various explanations then lead a brief discussion about the conditions necessary for a seed to break out of it’s dormant state and into the germination phase of development.

-         Make a list on the board of the resources required for the seed to grow.

-         Explain procedure to students:  Each group will draw the external and internal anatomy of both a dormant and germinating seed.  Then they will label the prominent structures and complete the questions on the lab sheet.

-         Divide students into groups and dismiss them to their lab stations.

 

(Introduction should take no more than 20-25 minutes for lecture and briefing)

 

Body of Lesson:  Guide the students as they observe the different phases of seed growth.  Put up overhead transparencies with labeled seed structures on them so the students can identify something that may not be apparent at first. 

-         Students should first draw the external anatomy of the dormant seed, then the internal.

-         Next students should draw the outside of the germinated seed, then the internal.

-         Help students label the important structures on each drawing and answer the questions.

 

Conclusion of Lesson:  Leave about 10 minutes to clean up the lab stations and get students back to their seats. 

-         Bring closure to the experience by leading a discussion on human involvement in the process of germination.  The conditions required for a seed to break out of dormancy can be manipulated by growers, and they must account for factors like weather, pests, etc.

-         Ask questions like: Why do growers have to monitor the weather closely?  What types of pests could interfere with as a germinating seed grows into a young seedling? 

-         Students may not consider herbivores as pests initially, but at the early stages of development, a simple fence is all a farmer may need to protect his crop.

-         Collect any question sheets that may be completed.  Any students that did not complete the questions or labeling may do so at home.

 

Assessment Plan:

-         The handout provided to the students calls for them to provide a definition of germination then draw a picture of a germinating seed.  This is a good way to assess their understanding of the processes taking place, as dormancy is broken.

-         Leading a discussion before and after the activity will clarify any new and/or prior knowledge acquired throughout the activity regarding the conditions necessary for germination to begin.

 

Extensions and Adaptations:  It is difficult to accurately time the germination process.  Six weeks is a typical time frame, however as all scientists know, this may not always be the case.  In the event of seeds not germinating in time for class, there is an alternative; pinto beans germinate in roughly 24 hours under the same conditions.  It always helps to have a backup plan, so prepare the pinto beans a few days before class to ensure there is an observable sample for the students.  Another idea at the end of the activity is to provide the students with a paper cup filled with soil.  Now the students can plant their germinating seeds and take them home.