Gene for smooth seed coat is dominant over gene for wrinkled seed coat. 2 heterozygous pea plants with smooth seed coat were crossed and produced a total of 14640 seed. How many seeds had wrinkled seed coat? Show your working.
First, we need to determine the genotype of the parents. We know that both parents have smooth seed coat, so they must be heterozygous (Ss) because smooth seed coat is dominant.
Parent 1: Ss
Parent 2: Ss
To solve the problem, we can use a Punnett square to figure out the possible offspring genotypes:
| | S | s |
|---|---|---|
| S | SS | Ss |
| s | Ss | ss |
The offspring will have the genotypes SS (smooth), Ss (smooth), or ss (wrinkled).
We can use the following formula to determine the expected number of offspring with a particular genotype:
Expected number = (total number of offspring) x (probability of that genotype)
The probability of getting an SS offspring is 1/4 (from the Punnett square above). Similarly, the probability of getting an Ss offspring is 1/2, and the probability of getting an ss offspring is 1/4.
To find the expected number of each genotype, we can use the formula above:
Expected number of SS offspring = (14640) x (1/4) = 3660
Expected number of Ss offspring = (14640) x (1/2) = 7320
Expected number of ss offspring = (14640) x (1/4) = 3660
Since wrinkled seed coat is only seen in the ss genotype, the number of seeds with wrinkled seed coat is equal to the expected number of ss offspring, which is 3660.
Therefore, 3660 seeds had a wrinkled seed coat.