In order to see precise cells, living cells are better to observe to get the correct information while dead cells do not do anything and you can't really get information out of it
Genotype ratio refers to the probability of each type of thing (in this case, round/yellow seeds) occurring based on the Punnett square. If you were to write out how many of each specific hybrid occurred in the square, you'd get:
1 RRYY
2 RRYy
2 RrYY
4 RrYy
1 RRyy
1 rrYY
1 rryy
What does this tell us? In this case, the only thing that matters is the capital letter (since that's the dominant trait and will determine whether the seed is/isn't round/yellow).
Looking at each one, you see some of them are the same - for example, RRYY and RRYy both end up as round and yellow. RrYy is too, as is RrYY.
So, you end up with 9 round and yellow; 3 round and not yellow; 3 not round and yellow; 1 not round and not yellow.
Sometimes when I go use the bathroom I like to poop , wipe my butt and smell like the poop on the napkin. Sometimes it gets my nose so I have to wipe my nose off then I stand up and watch it go down the toilet ;)