Section 6.3 Study Guide: Mendel and Heredity
Vocabulary
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Trait
Genetics
Purebred
Cross
Law of segregation
Review Questions
1. What is genetics?
The study of biological inheritance patterns and variation in organisms.
2. Whose early work is the basis for much of our current understanding of genetics?
Gregor Mendel
3. How did Mendel’s views on inheritance differ from the views of many scientists of his time?
Mendel recognized that traits are inherited as discrete units, whereas many others believed that
traits were “blended” together.
4. Mendel’s data revealed patterns of inheritance. In designing his experiments, Mendel made three
important choices that helped him see patterns of inheritance. In the table below, list Mendel’s
three choices and write an example of how he put each of these choices into action.
Mendel’s Choices
a)Control over breeding
Examples
Removed stamens (male part of plant) and hand
fertilized the pistil with pollen from a pea plant of
his choice.
b)use of purebred plants
Used self-pollinating, purebred pea plants
c)Studied “either-or” traits
Looked at traits that did not have intermediate
characteristics. Traits such as pea shape, color,
flower color, pod shape, pod color, etc.
5. Why did Mendel use pea plants? Pea plants reproduce quickly and he could control how they mate.
6. What was Mendel’s experimental process? Please summarize it by filling in the boxes below (steps
1 and 3 are already filled out).
Step 1: Bred flowers resulting in F1 generation with dominant phenotype.
Step 2: Allowed F1 generation to self-pollinate.
Step 3: Resulted in F2 generation with both dominant and recessive phenotypes.
Step 4: Calculated the phenotypic ratios in the F2 generation.
7. Mendel concluded that traits are inherited as “discrete units.” What do we call these discrete units
today? Genes
8. What two conclusions make up Mendel’s law of segregation? Organisms inherit two copies of each
gene, one from each parent. Genes segregate during gamete formation, so organisms donate only
one copy of each gene in their gametes.
9. Segregation means “separation.” What is “segregated” in Mendel’s law of segregation?
The discrete units, or genes. The result of the separation of chromosomes during meiosis.
10. What does “purebred” mean?
A genetically uniform line of organisms.