ch 11

• What genetic principle suggests that genetic material from parents blends together?

  The "blending" hypothesis
• What does the "particulate" hypothesis propose about inheritance?

  It proposes that parents pass on discrete heritable units called genes.
• Who documented the particulate mechanism of inheritance through experiments?

  Mendel
• What organism did Mendel use for his experiments on heredity?

  Garden peas
• What was remarkable about Mendel's theory of inheritance?

  He developed it before understanding how chromosomes behave.
• What are the advantages of using pea plants for genetic studies?

  They have distinct heritable features, controlled mating, and both reproductive organs.
• What are character variants in pea plants called?

  Traits
• What does it mean for a plant to be true-breeding?

  It produces offspring of the same variety when self-pollinated.
• What is the term for the process of mating two contrasting true-breeding varieties?

  Hybridization
• What are the F1 generation offspring of the P generation called?


  F1 generation
• What was the result when Mendel crossed true-breeding white and purple flowered pea plants?

  All F1 hybrids had purple flowers.

  
• What ratio of purple to white flowers did Mendel observe in the F2 generation?

  About three to one

  
• What conclusion did Mendel draw about the white flower factor in the F2 generation?

  It was not diluted or destroyed as it reappeared.
• How did Mendel classify the purple flower color in his experiments?

  As a dominant trait
• What did Mendel call the "heritable factor" that we now refer to as a gene?

  Heritable factor
• What are the four concepts that make up Mendel's model of inheritance?

  Alternative versions of genes, two alleles per character, dominance of alleles, and law of segregation.

  
• What are alternative versions of genes called?

  Alleles
• How many copies of every chromosome does each cell have?

  Two copies
• What does it mean for an organism to be homozygous?

  It has two identical alleles for a character.
• What is the difference between phenotype and genotype?

  Phenotype is physical appearance, while genotype is genetic makeup.
• What is a testcross used for?

  To determine the genotype of an individual with a dominant phenotype.
• What happens if any offspring from a testcross display the recessive phenotype?

  The mystery parent must be heterozygous.
• What is a monohybrid cross?

  A cross between individuals that are heterozygous for one character.

  
• What does the law of independent assortment state?

  Each pair of alleles segregates independently during gamete formation.
• What is the expected phenotypic ratio from a dihybrid cross?

  Approximately 9:3:3:1

  
• In the practice dihybrid problem, what fraction of the offspring will have barbed, short bodies when crossing Bbll with BbLl?

  3/8 or 38%
• What does it mean for genes located near each other on the same chromosome?

  They tend to be inherited together.
• What is the significance of Mendel's law of segregation?

  It accounts for the 3:1 ratio observed in the F2 generation.

  
• How can a Punnett square be used in genetics?

  It predicts the results of a genetic cross between individuals of known genetic makeup.

  
• What does a capital letter represent in a Punnett square?

  A dominant allele

  
• What does a lowercase letter represent in a Punnett square?

  A recessive allele

  
• What is the relationship between dominant and recessive alleles in terms of phenotype?

  The dominant allele determines the organism's appearance if present.
• What is the expected outcome of a testcross involving a dominant phenotype?

  Offspring may display either the dominant or recessive phenotype.
• What is the significance of Mendel's experiments with garden peas?

  They laid the foundation for the principles of heredity and genetics.
• How did Mendel's work contribute to our understanding of genetics?

  He identified laws of inheritance that explain how traits are passed from parents to offspring.
• What is the phenotypic ratio for hybrids that are heterozygous for both traits when the traits are on separate chromosomes?

  1. 3:3:1

  
• What traits are being studied in the aquatic arthropod Cyclops?

  • Antennae: barbed (B) or smooth (b)
  • Body length: long (L) or short (l)
• If a short-bodied Cyclops heterozygous for barbed antennae is crossed with one that is heterozygous for both traits, what fraction of the offspring will have barbed, short bodies?

  3/8 or 38%
• What is the genotype of the short-bodied Cyclops that is heterozygous for barbed antennae in the cross Bbll x BbLl?

  Bbll
• How do we predict the outcome of crosses involving multiple characters in genetics?

  By using probability and mini-Punnett squares