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On crossing red & ehite flowered plants ...

On crossing red & ehite flowered plants the ration of red and white flowered plnts in `F_(2)` generation was `60:20,` then on selfing the heterozygous red flowered plants, the offsprings would be :-

A

`72:24`

B

`40:60`

C

`52:48`

D

`84:16`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the genetic cross between red and white flowered plants and determine the offspring ratios when selfing heterozygous red flowered plants. ### Step-by-Step Solution: 1. **Identify the Parent Plants**: - We have red flowered plants and white flowered plants. Let's denote the red flower allele as 'R' (dominant) and the white flower allele as 'r' (recessive). 2. **Determine the F1 Generation**: - When we cross a homozygous red flowered plant (RR) with a homozygous white flowered plant (rr), all F1 offspring will be heterozygous red (Rr). 3. **Analyze the F2 Generation**: - When the F1 plants (Rr) are selfed (Rr x Rr), we can use a Punnett square to determine the F2 generation. - The Punnett square for Rr x Rr is as follows: ``` R r ------------ R | RR | Rr | |-------|------| r | Rr | rr | ``` 4. **Count the Offspring**: - From the Punnett square, we see the following genotypes: - 1 RR (homozygous red) - 2 Rr (heterozygous red) - 1 rr (homozygous white) - This gives us a phenotypic ratio of 3 red (1 RR + 2 Rr) to 1 white (1 rr). 5. **Confirm the Ratio**: - The ratio of red to white flowered plants in the F2 generation is 3:1. Given that the question states the ratio of red to white flowered plants is 60:20, we can simplify this to 3:1, confirming our understanding. 6. **Determine the Offspring Ratio from Selfing Heterozygous Plants**: - Since we are selfing the heterozygous red flowered plants (Rr), the offspring will also follow the 3:1 ratio of red to white flowers. 7. **Conclusion**: - The offspring from selfing the heterozygous red flowered plants will yield a phenotypic ratio of 3 red flowered plants to 1 white flowered plant. ### Final Answer: The offspring would be in the ratio of 3 red flowered plants to 1 white flowered plant (3:1). ---
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