Dominant and recessive traits examples

📚 Quick Study Guide

• 🌱 Dominant Traits: These traits are expressed when only one copy of the dominant allele is present. Think of them as the "stronger" gene.
• ⬇️ Recessive Traits: These traits are only expressed when two copies of the recessive allele are present. They're "weaker" and get masked by dominant traits.
• 🧬 Alleles: Different versions of a gene. For example, a gene for eye color might have alleles for blue eyes and brown eyes.
• 🧮 Genotype vs. Phenotype: Genotype is the genetic makeup (e.g., BB, Bb, bb), while phenotype is the observable trait (e.g., brown eyes, blue eyes).
• ➕ Homozygous: Having two identical alleles for a trait (e.g., BB or bb).
• ➖ Heterozygous: Having two different alleles for a trait (e.g., Bb). In this case, the dominant trait is expressed.
• 💡 Punnett Squares: A tool used to predict the genotypes and phenotypes of offspring. They help visualize how traits are inherited.

Practice Quiz

1. What is a dominant trait?
   1. A) A trait that is only expressed with two copies of the allele.
   2. B) A trait that is always expressed when at least one copy of the allele is present.
   3. C) A trait that is never expressed.
   4. D) A trait that changes over time.
2. If 'B' represents the dominant allele for brown eyes and 'b' represents the recessive allele for blue eyes, what is the phenotype of an individual with the genotype 'Bb'?
   1. A) Blue eyes
   2. B) Brown eyes
   3. C) A mix of blue and brown eyes
   4. D) No eye color
3. What is a recessive trait?
   1. A) A trait that is always expressed.
   2. B) A trait that is only expressed when two copies of the allele are present.
   3. C) A trait that disappears after one generation.
   4. D) A trait that is stronger than a dominant trait.
4. Which of the following genotypes is homozygous recessive?
   1. A) BB
   2. B) Bb
   3. C) bB
   4. D) bb
5. What does 'heterozygous' mean?
   1. A) Having two identical alleles for a trait.
   2. B) Having two different alleles for a trait.
   3. C) Having no alleles for a trait.
   4. D) Having three alleles for a trait.
6. In pea plants, 'T' is the allele for tallness and 't' is the allele for shortness. If a heterozygous tall plant (Tt) is crossed with a homozygous short plant (tt), what percentage of the offspring are expected to be short?
   1. A) 0%
   2. B) 25%
   3. C) 50%
   4. D) 75%
7. What tool is commonly used to predict the possible genotypes and phenotypes of offspring in genetics?
   1. A) A microscope
   2. B) A telescope
   3. C) A Punnett square
   4. D) A graduated cylinder