Question

Genetics Variation of Traits

Scenario
First Cross: Two pea plants were crossed, one had yellow seeds and one had green seeds. They
produced 508 seeds that were all yellow and no green.
Second Cross:The 508 yellow seeds were planted and allowed to self-pollinate (breed on their own
between plants) and produced 760 yellow seeded plants and 240 green seeded plants.
Scientific Explanation Based on the scenario on the first cross...
1. Make a key. Determine which trait must be dominant and recessive. Use a letter to represent
the two traits (dominant trait= capital letter and recessive trait=lowercase letter)
2. Determine the genotype of the parents.
3. Complete a punnett square.
4. Show genotype and phenotype ratios.

Answer 1

1. The dominant trait is yellow peas, whereas the recessive trait is green peas.

Let yellow peas be YY and green peas be Yy

2. the genotype of the parents are YY and Yy.

3. The punnett squares contain the first set of peas and second set.

4. You can see that in the second crossbreed, the different coloured square represents what will become green peas. Thus the ratio would be 3:1.