Answer:
The answer is 300.
Explanation:
When we cross GG and gg, 100% of the offspring will be heterozygous. If the heterozygotes show 75% penetrance meaning that there is a 75% probability that the plant that has the G gene will actually show it in it's phenotype.
So that means that 75% of the offspring should have dark green color, which means that 300 plants will have the expected phenotype and 100 will not.
I hope this answer helps.
