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Class
Date
Quick Lab
Identifying Dominant or Recessive Traits
You can determine some of the genotypes and all of the phenotypes for human
characters that are inherited as simple dominant or recessive traits.
MATERIALS
• pencil
• paper
Data Table
Dominant trait
Recessive trait
Cleft chin
No cleft
Dimples
No dimples
Hair above knuckles
Hairless fingers
Freckles
No freckles
Procedure
1. Look at the table above. For each character, circle the phenotype that best
matches your own phenotype.
2. Determine how many students in your class share your phenotype by recording
your results in a table on the chalkboard.
Analysis
1. Summarize the class results for each character.
2. Calculate the class dominant:recessive ratio for each character.
3. Critical Thinking
Applying Information For which phenotypes in the table can you determine a
person’s genotype without ever having seen his or her parents? Explain.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
BioSources:
TitleLab Program
31
Quick, Data, and
Chapter
Math Labs
Title
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TEACHER RESOURCE
Quick Lab
Identifying Dominant or Recessive Traits
Teacher Notes
TIME REQUIRED 20 minutes
SKILLS ACQUIRED
Summarizing
Calculating
Applying information
RATINGS
Teacher Prep–1
Student Setup–1
Concept Level–1
Cleanup–1
Easy
1
2
3
4
Hard
TIPS AND TRICKS
Emphasize that dominant phenotypes are not more common than recessive phenotypes. Point out that the expression of some phenotypes (such as freckles)
may be influenced by the environment.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
BioSources:
TitleLab Program
42
Quick, Data, and
Chapter
Math Labs
Title
Back
Lesson
Print PAGE
TEACHER RESOURCE
Name
Class
Date
Quick Lab
Identifying Dominant or Recessive Traits
You can determine some of the genotypes and all of the phenotypes for human
characters that are inherited as simple dominant or recessive traits.
MATERIALS
• pencil
• paper
Data Table
Dominant trait
Recessive trait
Cleft chin
No cleft
Dimples
No dimples
Hair above knuckles
Hairless fingers
Freckles
No freckles
Procedure
1. Look at the table above. For each character, circle the phenotype that best
matches your own phenotype.
2. Determine how many students in your class share your phenotype by recording
your results in a table on the chalkboard.
Analysis
1. Summarize the class results for each character.
Answers will vary. Note that the dominant trait will not necessarily
be the most common trait.
2. Calculate the class dominant:recessive ratio for each character.
Answers will vary.
3. Critical Thinking
Applying Information For which phenotypes in the table can you determine a
person’s genotype without ever having seen his or her parents? Explain.
The recessive traits. Recessive traits must be homozygous to be expressed.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
BioSources:
TitleLab Program
43
Quick, Data, and
Chapter
Math Labs
Title