Asked in Premeth past paper pool — Biology

In horses, black colouring (B) is dominant and chestnut colouring (b) is recessive. A homozygous black horse crosses with a chestnut horse.The percentage of offspring that are expected to be chestnut is:

Correct answer: A. 0%

  • A. 0%
  • B. 25%
  • C. 50%
  • D. 75%

Explanation

In this genetic cross, a homozygous black horse (BB) is crossed with a chestnut horse (bb). The offspring will all inherit one allele from each parent. Since the black horse can only pass on a 'B' allele and the chestnut horse can only pass on a 'b' allele, all offspring will be heterozygous (Bb) and exhibit black colouring because black (B) is dominant over chestnut (b). Therefore, 0% of the offspring will be chestnut.

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About Mendel's Laws of Inheritance

Mendelian inheritance explains how alleles separate into gametes and assort during reproduction, producing predictable genotype and phenotype ratios. Questions cover dominance, recessiveness, homozygous and heterozygous conditions, the laws of segregation and independent assortment, monohybrid and dihybrid crosses, test crosses and the limits caused by linked genes.

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