Download Name - Mrs. Eggleston

Name
Class
Date
17.1 Genes and Variations
Lesson Objectives
Define evolution in genetic terms.
Identify the main sources of genetic variation in a population.
State what determines the number of phenotypes for a trait.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart by
writing a strategy to help you remember the meaning of each term. One has been done for
you.
How I’m Going to Remember the
Meaning
Term
Definition
Allele
frequency
The number of times an allele
appears in a gene pool,
compared to the total number of
alleles in that pool for the same
gene.
Gene pool
A common group of genes, and
all their alleles, shared by a
population
Polygenic
trait
A trait controlled by two or more
genes
Single-gene
trait
A trait controlled by only one
gene
To carpool means to share a car, and a
gene pool is all the genes shared by a
population.
B. As you work through this lesson, you may find these terms in the activities. When you need to
write a key term or a definition, highlight the term or the definition.
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Name
Class
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BUILD Understanding
Concept Map A concept map helps you see how the topics you read about are related to one
another. Use the words and phrases below to fill in the empty spaces in the concept map.
Genetic recombination
Chromosomes
Genes
Crossing-over
Sources of
Genetic Variation
include
Lateral gene
transfer
Mutations
happens during
involve changes in
Meiosis
CHAPTER
MYSTERY
Epidemic Viruses, including flu viruses, have genes. The genes determine the viruses’
traits. What traits might make some viruses better at causing disease than other viruses are?
Write your ideas in the space below.
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Name
Class
Date
Single-Gene and Polygenic Traits
Polygenic Traits Some traits are controlled by only one gene. They are called single-gene
traits. Other traits are controlled by two or more genes. They are called polygenic traits. Human
height is an example of a polygenic trait.
Follow the directions.
1. Draw one bar for each height range.
The bar should show how many students have
heights in that range.
2. Draw a curve connecting the tops of the bars.
Height in cm
Number of Students
155–159
160–164
165–169
170–174
175–179
180–184
185-189
190–194
1
2
6
10
10
6
2
1
Answer the questions.
3. Circle the correct answer. What shape is the curve you drew?
bell curve
one-sided curve
irregular curve
4. What is the average height for this population?
A. 155–164 cm
B. 165–174 cm
C. 170–179 cm
D. 185–194 cm
5. Jane and Miguel are both 172 cm tall. Does that mean they have the same genotype? Why?
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