Examples of genetic inheritance patterns for 9th grade

🧬 Quick Study Guide

• 🌱 Mendelian Inheritance: 👨‍🌾 Follows the laws of segregation and independent assortment. Deals with traits controlled by single genes with distinct alleles.
• 🥇 Dominant Inheritance: 💪 Only one copy of the dominant allele is needed for the trait to be expressed.
• recessive: 🙈 Two copies of the recessive allele are needed for the trait to be expressed. Carriers have one copy and don't show the trait.
• 🤝 Codominance: 🩸 Both alleles are expressed equally. Example: ABO blood groups (A and B alleles).
• 🌸 Incomplete Dominance: 🎨 The heterozygous phenotype is a blend of the two homozygous phenotypes. Example: Red and white flowers producing pink flowers.
• 🔗 Sex-linked Inheritance: 🧬 Genes located on the sex chromosomes (X and Y). Usually X-linked since the X chromosome is larger.
• 🔄 Punnett Squares:** 📝 Used to predict the probability of offspring genotypes and phenotypes. Each parent contributes one allele per trait. Example: Monohybrid cross ($Aa \times Aa$) yields a genotypic ratio of 1:2:1 ($AA:Aa:aa$).

🧪 Practice Quiz

1. A plant with red flowers (RR) is crossed with a plant with white flowers (WW). If flower color exhibits incomplete dominance, what is the phenotype of the offspring?
   1. Red
   2. White
   3. Pink
   4. Red and White striped
2. In humans, the allele for brown eyes (B) is dominant over the allele for blue eyes (b). If a heterozygous brown-eyed man marries a blue-eyed woman, what percentage of their children will have blue eyes?
   1. 0%
   2. 25%
   3. 50%
   4. 75%
3. Which inheritance pattern involves both alleles being equally expressed in the phenotype?
   1. Dominant Inheritance
   2. Recessive Inheritance
   3. Codominance
   4. Incomplete Dominance
4. A man with blood type AB marries a woman with blood type O. What are the possible blood types of their children?
   1. A and B
   2. AB and O
   3. A, B, and O
   4. Only O
5. Hemophilia is an X-linked recessive disorder. If a carrier female (XHXh) has children with a normal male (XHY), what is the probability that their son will have hemophilia?
   1. 0%
   2. 25%
   3. 50%
   4. 100%
6. What is the expected phenotypic ratio of a monohybrid cross (Aa x Aa) if 'A' is completely dominant over 'a'?
   1. 1:1
   2. 3:1
   3. 1:2:1
   4. 9:3:3:1
7. Which of the following is NOT a characteristic of Mendelian inheritance?
   1. Traits are controlled by single genes.
   2. Alleles segregate during gamete formation.
   3. Independent assortment of alleles occurs.
   4. Traits are influenced by multiple genes.