Question

In a mono hybrid cross of heterozygous pea plant with round (R) yellow (Y) seeds there will be genotype ratio of 9 _____ 3,____ 3,____ and 1____ PLEASE PLEASE HELP IM KIND OF CONFUSED

Answer 1

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.