IB Biology: D3.2-Terminologies on Inheritance

Multiple Choice

Which of the following best describes the Law of Independent Assortment?

• Alleles for different traits are inherited independently of each other.

• Each parent contributes only one allele for each gene.

• Dominant alleles always mask recessive alleles.

• Traits are only determined by environmental factors.

Multiple Choice

Which terms are correctly matched with their definitions?

• Homozygous: two different alleles; Heterozygous: two same alleles

• Gene: a version of a trait; Allele: a portion of DNA

• Homozygous: two same alleles; Allele: a version of a gene

• Genotype: observable traits; Phenotype: genetic information

Multiple Choice

Explain how the concepts of dominant and co-dominant alleles differ, using examples from the monohybrid cross diagram.

• A dominant allele always masks the effect of a recessive allele in the heterozygous condition, while co-dominant alleles are both expressed equally in the phenotype — for example, red and white flowers producing pink offspring.

• A dominant allele is only expressed when both alleles are identical, while co-dominant alleles produce a completely new trait that is not related to either parent.

• Dominant alleles are stronger forms of genes that permanently suppress recessive alleles, while co-dominant alleles randomly express one of the two traits in each generation.

• In dominant inheritance, both alleles contribute equally to the phenotype, while co-dominance means only one allele is expressed.