Examkin

Question

Difficulty: EasyMendel's Second Law and Dihybrid Inheritance

In garden pea plants (*Pisum sativum*), tall stem height (TT) is dominant over dwarf stem height (tt), and yellow seed color (YY) is dominant over green seed color (yy). According to Mendel's Law of Independent Assortment, how many genetically distinct types of gametes can be produced by an F1F_1 plant with the genotype TtYyTtYy?

  1. A
    2 types
  2. 4 typesAnswer
  3. C
    8 types
  4. D
    16 types

Answer

4 types of gametes (TYTY, TyTy, tYtY, and tyty)
According to Mendel's Second Law (Law of Independent Assortment), alleles for different traits segregate independently during meiosis. For a dihybrid individual with genotype TtYyTtYy, the two alleles of the stem height gene (TT and tt) combine randomly with the two alleles of the seed color gene (YY and yy). Using the formula 2n2^n (where nn is the number of heterozygous gene pairs, here n=2n = 2), the number of distinct gamete types produced is 22=42^2 = 4, which are TYTY, TyTy, tYtY, and tyty.

Step-by-Step Solution

1
Identify the number of heterozygous gene pairs in the given genotype.
The genotype TtYyTtYy has two heterozygous gene pairs (n=2n = 2).
Mendel's Law of Independent Assortment states that allele pairs separate independently during gamete formation.
2
Calculate the number of possible unique gamete types using the formula 2n2^n.
22=42^2 = 4 distinct gamete types.
Where nn represents the number of heterozygous loci, 222^2 yields the total combinations.
3
List the distinct allele combinations to verify.
The four possible gametes are TYTY, TyTy, tYtY, and tyty.
Each gamete receives one allele from each gene pair independently.

Key Concept

Mendel's Law of Independent Assortment and Gamete Formation in Dihybrids
Rate this question

Topics

Mendel's Second Law and Dihybrid Inheritance

More questions from this topic