Analyzing Mendelian Genetics

Plant Height Experiment

  1. Mendel studied how garden peas inherited plant height. He started with two true-breeding lines, one producing tall plants, the other short plants. We will use the capital letter "T" to represent the tall allele and a lowercase "t" for the short allele.
    1. We call these plants the parental generation, abbreviated as the   ___   generation.
    2. What is the genotype for the true-breeding tall plants ? _____
    3. Describe the phenotype for the tt plants. _______________________________
    4. Why are these plants called homozygous? ________________________________
  2. Mendel crossed the two lines. He did this by placing pollen (male gametes) of a tall plant on the pistil (female part) of a short plant. Remember that a gamete will have ½ of the parent's genome. He saved the resulting seeds.
    1. What is the gamete allele of the true-breeding tall plants? ______
    2. What is the gamete allele of the true-breeding short plants? _______
  3. Mendel grew the seeds of this first crossed generation. He found that the plants were all tall!
    1. The plants grown from the seeds are known as the   ____   generation.
    2. What is the genotype of the plants ? __________
    3. Which height trait is dominant? _______________
    4. Are these plants homozygous for height? ________
    5. The gametes of these F1 plants have two possible alleles: ________     _______
  4. Mendel then did nothing... these F1 plants self-fertilized themselves. When Mendel planted the resulting F2 seeds he found that 75% of the F2 plants were tall and 25% were short.
    1. What are the three genotypes contained in the F2 seeds? _____     _____     _____
    2. What is the genotype of the short plants ? _______
    3. What are the genotypes of the tall plants ? _______     _______
    4. Which two genotypes would be true-breeding now ? _______     _____
    5. Which two genotypes would be homozygous ? _______     ______
 

Pod Color Experiment

  1. Mendel also studied the pod color of garden peas. He started with two true-breeding lines, one producing green pods, the other yellow pods. We will use letter "G" to represent the green pod allele and a lowercase "g" for the yellow pod allele.
    1. We call these true-breeding plants the   ____   generation.
    2. What is the genotype for the true-breeding green pod plants ? ________
    3. Describe the phenotype for the gg plants. _______________________________
    4. Are these plants homozygous for pod color? _____________
    5. What is the gamete allele of the true-breeding green pod plant? _______
    6. What is the gamete allele of the true-breeding yellow pod plant? ________
  2. Mendel crossed these two lines, saved the resulting F1 seeds and grew them into F1 plants.
    1. What is the genotype of the plants ? _________
    2. Describe the phenotype of the plants. ___________________________
    3. Are these plants homozygous for pod color? _________
    4. The gametes of the F1 plants have two possible alleles: ______     _______
  3. Mendel allowed the F1 plants to self-fertilize. When he planted the resulting F2 seeds they grew into a mix of green and yellow pod F2 plants.
    1. What percentage of the plants had a GG genotype? ________
    2. What percentage of the plants had a Gg (or gG) genotype? ________
    3. What percentage of the plants had a gg genotype? _________
    4. Describe the phenotype for the Gg (or gG) plants. ____________________________
    5. Which two genotypes would be true-breeding now ? _______     ______
    6. Which genotypes would be heterozygous ? _______     ______
 

Using Punnett squares to analyze the plant height experiment

Use this square to analyze the F1 generation.

Parent 1 gametes Parent 2 gametes
 
 

 

 

 

 

Use this square to analyze the F2 generation.

Parent 1 gametes Parent 2 gametes
 
 

 

 

 

 


Using Punnett squares to analyze the pod color experiment

Use this square to analyze the F1 generation.

Parent 1 gametes Parent 2 gametes
 
 

 

 

 

 

Use this square to analyze the F2 generation.

Parent 1 gametes Parent 2 gametes