• If you use the Baby Boom Web Lab, check students’ printed quiz results. If a printer is not available, assess students by having them write a summary of how the lab activity demonstrates patterns of inheritance.
• If you use the Zork Genetics lab, collect and assess students’ answers to the lab questions.
• Quiz students on vocabulary from the lesson.
• Check students’ answers to the short-answer questions.

Background Knowledge

This unit requires students to have background knowledge of the processes of mitosis and meiosis (i.e., the cell cycle). Students should also have an understanding of the basic structure of the DNA molecule.

Note: Students must understand dominant and recessive inheritance patterns and be able to complete a Punnett square in order to be successful in this lesson.

Part 1

Tell students, “In today’s lesson we are going to learn how one man’s curiosity in the 1800s helped us know how our physical traits are passed from parents to their children. Let’s get started by having you pick one characteristic that you have in common with another family member.” Allow each student to share his/her characteristic, using this as a lead-in to the lesson.

If students are already familiar with this lesson’s vocabulary, have them complete the Vocabulary Worksheet for review (S-B-5-1_Vocabulary Worksheet and KEY.doc). If needed, present notes on the vocabulary from this lesson before students complete the worksheet.

Explain Gregor Mendel’s experiment and observations about the characteristics of pea plants and flowers. Show students the Mendel’s Peas: Characteristics transparency (S-B-5-1_Mendel’s Peas-Characteristics.doc). Alternatively, to make the presentation of Mendel’s experiment interactive, use color cut outs of pea seeds, pods, and flowers to match the color of the peas, pods, and flowers used by Mendel. As you explain Mendel’s findings, have student volunteers stand in front of the class and hold the appropriate pea seed or flower to show the “parents” and an additional student volunteer to represent their respective offspring. Once students have observed the visual of Mendel’s experiment, create additional combinations allowing students to predict what the new outcomes will be. If needed, this is a good point to review Punnett squares. Note: Monohybrid crosses are sufficient to prepare students for the lab activity in Part 2.

Part 2

Review the previous lesson’s content by asking students to describe the following patterns of inheritance: dominant, recessive, and incomplete dominance.

In small groups, have students complete a lab activity on patterns of inheritance:

• If computers with Internet access are available, have students do the Baby Boom Web Lab (see Related Resources). After the lab, have students take the quiz and print their results. If a printer is not available, assess students by having them write a summary of how the lab activity demonstrates patterns of inheritance.
• If computers with Internet access are not available, have students carry out the Zork Genetics lab activity and answer the Single Cross Problems questions (S-B-5-1_Zork Genetics Lab-Student Version.doc). Before students begin the activity, read through the “Background” section aloud and explain that there are exponential possibilities for genetic crosses. Review all answers with the class (S-B-5-1_Zork Genetics Lab-Teacher Version.doc).

Assign the short-answer items below as homework or use them as an extension to the lesson.

a)      Detached earlobes are a recessive trait. If a mother has detached earlobes and a father has detached earlobes, what is the chance that the child will also have detached earlobes? Explain.

b)      The presence of freckles is a dominant trait. Charlene has freckles. Ronald does not have freckles. Contrast Charlene and Ronald’s phenotype and genotype.

Rubrics:

a)      Detached earlobes are a recessive trait. If a mother has detached earlobes and a father has detached earlobes, what is the chance that the child will also have detached earlobes? Explain.

Sample answer: Since detached earlobes are a recessive trait, an individual must have two recessive alleles if they have this trait. If the mother has detached earlobes (ee) and the father has detached earlobes (ee), then you cross these two in a Punnett square. The result shows that there is a 100% chance that their children will have detached earlobes (ee).

b)      The presence of freckles is a dominant trait. Charlene has freckles. Ronald does not have freckles. Contrast Charlene and Ronald’s phenotype and genotype.

Students can choose their own letter for the trait of freckles. Most often, they will choose the letter “f.” Charlene’s genotype can be either Ff or FF because she has the dominant trait. Her phenotype is the presence of freckles. Ronald’s genotype can only be ff, since he does not have the trait. His phenotype is a lack of freckles.

Extension:

• For students requiring further practice with the standards, have them complete the Vocabulary Worksheet with a partner and review the answers, having them correct any mistakes. Ask them to them create flashcards to review the vocabulary.
• If students did not previously complete the short-answer questions at the end of the lesson, use those questions for an extension activity.