QUESTION IMAGE
Question
a horticulturalist wants to produce geraniums with specific characteristics. she knows that the trait of red flowers is governed by the allele r (rr and rr) and the trait of white flowers is governed by the allele r(rr). the horticulturalist plans to cross a geranium that is true - breeding for red flowers with a geranium that is true - breeding for white flowers. which punnett square best describes this cross? punnett square image with r, r at top, r, r on left, and cells rr, rr, rr, rr
- First, identify the genotypes of the parent plants: The true - breeding red - flowered geranium has the genotype RR (since it is true - breeding for the dominant red trait), and the true - breeding white - flowered geranium has the genotype rr (since it is true - breeding for the recessive white trait).
- When we set up the Punnett square for a cross between RR and rr, the gametes from the RR parent are all R, and the gametes from the rr parent are all r.
- Looking at the given Punnett square option: The top row (gametes from one parent) should be r and r (from rr), and the left - hand column (gametes from the other parent) should be R and R (from RR). When we fill in the Punnett square, the offspring genotypes should be Rr (from R×r) in all cells. Wait, but in the provided Punnett square in the question, the left - hand column has R and r? No, that's an error. Wait, no, the true - breeding red is RR, so it can only produce R gametes, and the true - breeding white is rr, producing only r gametes. So the correct Punnett square should have the gametes of the red parent (RR) as R (top and bottom, if we consider a 2x2 square) and the gametes of the white parent (rr) as r (left and right). Then all offspring are Rr. But in the given option, the left - hand side has R and r? Wait, maybe there was a typo in the option presentation. But among the given option (the one with top row r, r; left column R, r? No, the first row of the Punnett square in the option: top row is r, r; first column (left) is R, r. Wait, no, the true - breeding red is RR, so it can only produce R gametes. So the correct Punnett square should have the male or female gametes as R (both) and the other as r (both). So the Punnett square with top row r, r and left column R, R (but in the given option, left column is R, r? Wait, maybe the option is mis - printed, but the key is that the cross is RR × rr. So the gametes from RR are R, R and from rr are r, r. So the Punnett square should have four cells all with Rr. The given option in the question (the one with top r, r; first row R gives Rr, Rr; second row r gives rr, rr) is incorrect? Wait, no, maybe the true - breeding red was mis - identified. Wait, no, the problem says true - breeding for red is RR (since red is RR or Rr, true - breeding would be RR) and true - breeding for white is rr. So cross RR × rr. Gametes: RR produces R, R; rr produces r, r. So Punnett square:
| r | r | |
|---|---|---|
| R | Rr | Rr |
But in the given option, the left column has R and r. That's a mistake. But maybe the option was supposed to have the red parent as Rr? No, it's true - breeding, so RR. Wait, maybe the question has a typo, but among the given option (the one presented), if we assume that maybe the red parent was Rr (but it's true - breeding, so it should be RR). But the only option provided (the one with top r, r; left R, r) – no, the correct answer should be the Punnett square where all offspring are Rr, which would be the case if the gametes of the red parent are R (both) and white parent are r (both). So the given option (the first one, with top r, r; left R, r – no, that's wrong. Wait, maybe I misread. Let's re - examine: The horticulturalist crosses true - breeding red (RR) with true - breeding white (rr). So the Punnett square should have:
Parent 1 (RR) gametes: R, R
Parent 2 (rr) gametes: r, r
So the Punnett square is:
| r | r | |
|---|---|---|
| R | Rr | Rr |
So the correct Punnett square is the one where the two gametes from the red parent are R (so the left - hand column has R in…
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The Punnett square with the top row (gametes of the white - flowered parent) as \( r, r \) and the left - hand column (gametes of the red - flowered parent) as \( R, R \) (producing \( Rr \) in all four cells) is the correct one. If we consider the provided option in the question (with top row \( r, r \); first row (left - hand side) \( R \) and second row (left - hand side) \( r \) – this is incorrect in the second row, but if we assume a typo and the left - hand column should be \( R, R \), then this (the provided option with top \( r, r \) and first row \( R \)) is the closest, as the first row (with \( R \)) produces \( Rr \) (correct for the cross of \( RR\times rr \), since \( R \) from red and \( r \) from white give \( Rr \)). The second row (with \( r \)) is incorrect, but maybe it's a misprint, and the intended correct Punnett square is the one that shows \( Rr \) from the cross of \( R \) (from \( RR \)) and \( r \) (from \( rr \)) in the first row, so the answer is the Punnett square with top \( r, r \) and first row \( R \) (producing \( Rr, Rr \)).