If you cross two mystery pea plants what is probability of seeing pea plant with tall stesm and white floewrs
The correct answer and explanation is:
To answer the question about the probability of seeing a pea plant with tall stems and white flowers when crossing two mystery pea plants, we need some assumptions about the genetics involved.
Step 1: Define the traits and alleles
- Tall stems (T) are dominant over short stems (t).
- Purple flowers (P) are dominant over white flowers (p).
This means:
- Tall stem: T allele (dominant)
- Short stem: t allele (recessive)
- Purple flowers: P allele (dominant)
- White flowers: p allele (recessive)
The plant must have at least one T allele to be tall and two p alleles (pp) to have white flowers.
Step 2: Understand the mystery plants’ genotype possibilities
Because the parents are mystery plants, we don’t know their exact genotype. But to calculate the probability, let’s consider a typical scenario often presented in Mendelian genetics:
Assume both mystery plants are heterozygous for both traits (TtPp), meaning they have:
- One dominant and one recessive allele for height (Tt)
- One dominant and one recessive allele for flower color (Pp)
This is a common assumption when parents have unknown genotypes but show dominant phenotypes.
Step 3: Create the Punnett square
Cross: TtPp x TtPp
Each parent produces four types of gametes:
- TP
- Tp
- tP
- tp
When crossing these gametes, the offspring genotypes can be calculated.
Step 4: Calculate probability of tall stem (T_)
Tall stems mean genotype is either TT or Tt.
- Probability of tall = 3/4 (since only tt is short)
Step 5: Calculate probability of white flowers (pp)
White flowers require pp genotype.
- Probability of white flowers (pp) = 1/4
Step 6: Combine probabilities
Because the two traits assort independently:
- Probability tall stem and white flowers = Probability tall × Probability white
= (3/4) × (1/4) = 3/16
Final answer:
The probability of getting a pea plant with tall stems and white flowers is 3/16.
Explanation in 300 words:
When crossing two pea plants heterozygous for stem height (Tt) and flower color (Pp), each trait segregates independently according to Mendel’s law of independent assortment. The tall stem trait (T) is dominant over short stem (t), and purple flower color (P) is dominant over white flowers (p).
Each parent plant can produce four types of gametes: TP, Tp, tP, and tp. When crossed, these gametes form 16 possible genotype combinations for the offspring. For stem height, the offspring genotypes can be TT, Tt, or tt. Both TT and Tt result in tall stems, while only tt leads to short stems. The probability of an offspring being tall is therefore 3 out of 4.
For flower color, only the homozygous recessive genotype (pp) results in white flowers. The probability of an offspring having white flowers is 1 out of 4.
Since these traits are inherited independently, we multiply their individual probabilities to find the combined probability of offspring having both tall stems and white flowers. This is (3/4) for tall stems multiplied by (1/4) for white flowers, resulting in 3/16.
Thus, when crossing two heterozygous pea plants, about 18.75% of their offspring will have tall stems and white flowers. This genetic analysis helps explain how different traits can combine and why certain combinations appear in predictable ratios in offspring.