Genetics Practice Problems

Genetics Practice Problems

• Curly vs. Straight Hair: Curly hair (H) is dominant; two heterozygous parents (Hh) can yield 3/4 curly and 1/4 straight offspring.

• Flower Bloom Size Dominance:

  • Two big-bloomed flowers producing small-bloomed offspring suggests big bloom is dominant.
  • Two big-bloomed parents with all big offspring cannot determine dominance.
  • A cross between big and small blooms resulting in 50% of each phenotype cannot establish dominance.
  • Two small blooms yielding 3/4 small and 1/4 big indicates small blooms are dominant.

• Cat Fur Color Inheritance:

  • Black (F^B) and tan (F^T) fur produces codominant tabby (F^BF^T) cats.
  • Cross of black and tabby cats yields no chance for tan offspring (0%).

• Incomplete Dominance in Hair Type:

  • Assignments: RR = curly, Rr = wavy, rr = straight.
  • For wavy children, both parents must be heterozygous (Rr).
  • Two wavy parents have a 25% chance of having straight-haired children.

• Eye Color Genotypes:

  • Parental cross of GGBb and Ggbb yields possible genotypes and phenotypes with ratios of 2/4 hazel and 2/4 green eyes.

• Wheat Kernel Color as a Polygenic Trait:

  • Two genes (A, B) control kernel colors ranging from dark red (all dominant) to white (all recessive).
  • Cross of AaBB and AaBb results in genotype/phenotype ratios of 1/8 dark red, 3/8 red, 3/8 pink, and 1/8 light pink.

• Blood Type Inheritance:

  • Man with blood type O has parents with genotypes I^Ai and I^Bi.
  • Man's genotype is ii; the chance of having a child with blood type O is 25%.
  • Possible blood types for offspring with a B-type woman depend on her genotype, resulting in either B or O blood types.

• Inheritance in Children from Blood Type Parents:

  • Father O- with children A+ and B- indicates mother must be I^Ai or I^Bi Dd.
  • Potential phenotype ratios from the dominant cross are 1/4 A+, 1/4 A-, 1/4 B+, 1/4 B-.
  • Child A+ crossed with B+ offers various genotype and phenotype ratios.

• Hemophilia Genetics:

  • Hemophilia (X^h) is a recessive sex-linked disorder; father X^hY and mother X^HX^H can have hemophiliac children.
  • Chance of a daughter from this couple being hemophiliac is 50%.

• Duchenne Muscular Dystrophy:

  • It is a sex-linked recessive condition more common in males due to X chromosome inheritance patterns.
  • Cross between affected father and carrier mother yields a 50% chance of a normal child.
  • Normal couple's son with the disease raises a 50% chance for future sons to also be affected.

• General Notes on Pedigrees: Pedigrees are used for tracing inheritance patterns through family trees and understanding genetic relationships.

• Short Cut Method in Genetics: Techniques, formulas, and methods for easier problem-solving in genetic inheritance.

Test your knowledge on dominant and recessive traits with these genetics practice problems. The flashcards include scenarios like hair types and flower blooms, challenging you to identify traits and draw Punnett squares for offspring. Perfect for students studying genetics.