The Importance of Fruit

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Objective

Students will relate the structure of fruit to their function in plant propagation.

Big Idea

Find out today how the development of fruit made angiosperms more successful than gymnosperms.

What Students will Learn in this Lesson

1 minutes

In today's lesson, students will dissect multiple kinds of fruit so that they can understand the diversity of fruits in angiosperms. Then students compare angiosperm fruit with gymnosperms. Here is an overview of what students will learn today. 

Hook/Check for Understanding

3 minutes

Have students revisit their responses from the "Seedlings in a Jar” assessment probe. Ask students the following questions to help them better understand the process of seed germination.

  • From where do seeds come?
  • From your experience, under what conditions do seed sprout plants best?

 

Next, ask students to define fruit (from a biological perspective) using the Frayer method.   

Using the biological definition of fruit, ask student to decide which of the following would be classified as a fruit.

  • tomato
  • potato
  • green pepper
  • apple
  • strawberry
  • hedge apple
  • rose hip
  • carrot
  • radish

Remind students that when a plant sheds its flower, the fertilized egg will develop into a seed. The ovary wall that surrounds the seed will often develop into a fruit in angiosperms.  


Station 1: Apple Dissection (Accessory Fruit)

10 minutes

At this station, student pairs will dissect an apple which will serve as a model organism for an accessory fruit. The following equipment and supplies will be needed for this activity:

For each student pair

  • scalpel
  • forceps
  • probe
  • dissecting tray
  • magnifying glass
  • apple
  • a picture of an apple blossom

Students should look at the base of the fruit to see the remnants of the flower.  They should notice the tiny, withered sepal remains. Using the probe, have students pull back the edges of the sepals to see the remains of the stigma and style. (Note:  These are tiny structures so students may need to use a magnifying glass to view them.) Using a scalpel, cut the apple lengthwise into two pieces.  Students should make a sketch of the apple half in their lab notebook labeling the fruit, core, seeds, sepal, stigma, and style. Using the scalpel, they should very carefully remove the core. Students should sketch the structure in their lab notebook. Next, they should extract the seeds. Ask student how many seeds an apple contains?  Does this correlate to any part of the flower? Students should look at the flower blossom to see if they notice any correlation. (Note: See Accessory Fruit Dissection for more specific instructions.)

While dissecting, students should consider the following questions and write their responses in their lab notebook.

  • What is the primary function of this fruit?
  • Is this fruit a monocot or a dicot?  What characteristics of the fruit help you in this identification?

 

Station 2: Strawberry Dissection (Aggregate Fruit)

10 minutes

For this station, student pairs will dissect a strawberry which will serve as a model organism for an aggregate fruit. The following equipment and supplies will be needed for this activity:

For each student pair:

  • scalpel
  • forceps
  • probe
  • dissecting tray
  • magnifying glass
  • strawberry
  • a picture of a strawberry blossom

Students should look at the base of the fruit to see the remnants of the flower.  They should notice the tiny, wither sepal. Using the probe, have students pull back the edges of the sepals to see the remains of the stigma and style.  (Note:  These are tiny structures so students may need to use a magnifying glass to view them.) Using a scalpel, cut the strawberry lengthwise into two pieces.  Students should make a sketch of the strawberry half in their lab notebook labeling the fruit, core, seeds, sepal, stigma, and style. Students should sketch the structure in their lab notebook.  Next, they should extract the seeds.  Ask student how many seeds a strawberry contains?  Does this correlate to any part of the flower?  Students should look at the flower blossom to see if they notice any correlation. (Note: See Strawberry Dissection (Aggregate Fruit) for more specific instructions.)

While dissecting,students should consider the following questions and write their responses in their lab notebook.

  • What is the primary function of this fruit?
  • Is this fruit a monocot or a dicot?  What characteristics of the fruit help you in this identification?
  • List two ways that a strawberry differ from an apple anatomically?

Station 3: Sweetgum balls (Multiple Fruits)

10 minutes

At this station, student pairs will dissect a sweet gum fruit which will serve as a model organism for a multiple fruit. The following equipment and supplies will be needed for this activity:

For each student pair:

  • scalpel
  • forceps
  • probe
  • dissecting tray
  • magnifying glass
  • sweet gum fruit
  • a picture of a sweet gum flower

Students should look at the fruit to see the remnants of the flower.  They should notice the tiny, wither sepals. Using the probe, have students pull back the edges of the sepals to see the remains of the stigma and style. (Note:  These are tiny structures so students may need to use a magnifying glass to view them.) Using a scalpel, cut the sweet gum fruit lengthwise into two pieces.  Students should make a sketch of the sweet gum half in their lab notebook labeling the fruit, seeds, sepal, stigma, and style. Using the scalpel, they should very carefully remove the core.  Students should sketch the structure in their lab notebook.  Next, they should extract the seeds.  Ask student how many seeds a sweet gum fruit contains?  Does this correlate to any part of the flower?  Students should look at the flower to see if they notice any correlation. (Note: See Sweet Gum Dissection (Multiple Fruit) for more specific instructions.)

While dissecting,students should consider the following questions and write their responses in their lab notebook.

  • What is the primary function of this fruit?
  • Is this fruit a monocot or a dicot?  What characteristics of the fruit help you in this identification?
  • How does this fruit differ from the apple and the strawberry?  To which is it more similar?  

 

Station 4: Cherry Tomato Dissection (Simple Fruit)

10 minutes

At this station, student pairs will dissect a cherry tomato which will serve as a model organism for a simple fruit. The following equipment and supplies will be needed for this activity:

For each student pair:

  • scalpel
  • forceps
  • probe
  • dissecting tray
  • magnifying glass
  • cherry tomato
  • a picture of a tomato flower

Students should look at the base of the fruit to see the remnants of the flower. They should make observation of the outside of tomato. Using a scalpel, cut the tomato lengthwise into two pieces. Students should make a sketch of the tomato half in their lab notebook labeling the fruit, seeds, sepal, stigma, and style. Students should sketch the structure in their lab notebook. Next, they should extract the seeds. Ask student how many seeds a tomato contains? Does this correlate to any part of the flower? Students should look at the flower blossom to see if they notice any correlation. (Note: See Tomato Dissection (Simple Fruit) for more specific instructions.)

While dissecting,students should consider the following questions and write their responses in their lab notebook.

  • What is the primary function of this fruit?
  • Is this fruit a monocot or a dicot?  What characteristics of the fruit help you in this identification?
  • Compare the tomato with the other fruit that have been dissected today.  To which is the tomato most similar?  

Station 5: Pine Cone Comparison

10 minutes

At this station, student pairs will dissect both a male and female pine cone, which will serve as a model organism for conifers, a type of gymnosperm. The following equipment and supplies will be needed for this activity:

For each student pair:

  • scalpel
  • forceps
  • probe
  • dissecting tray
  • magnifying glass
  • one male pine cone 
  • one female pine cone
  • a picture of pine showing placement of both male and female cones

Students should first dissect the male cone. Then students should dissect the female cone. (Note: see Pine Cone Comparison for more specific instructions.)

While dissecting, students should consider the following questions and write their responses in their lab notebook.

  • What is the primary function of the male cone?
  • What is the primary function of the female cone?
  • How is their placement of the tree unique?
  • How does the female cone differ from a fruit from a monocot and a dicot?  In what type of situation would this make the cone more successful?

Putting it All Together: The Importance of Fruit in Seed dissemination

15 minutes

Ask students to explain how they think the seeds from the fruit they dissected today are dispersed. Use this powerpoint to help students compare the methods of seed dissemination to show the interrelationships between plant and their environment.  At the end of the lecture have students complete a graphic organizer summarizing and evaluating the different methods of seed dispersal.