Let's analyze and answer each part of the problem step-by-step.
### 1. Identifying the Generations
#### (a) The plants in the ___ F1 generation ___ were allowed to self-pollinate.
In Mendelian genetics, the F1 generation refers to the first generation of offspring obtained by crossing the parental (P) generation plants. These F1 plants are then allowed to self-pollinate to produce the F2 generation. Hence, the correct answer is:
The plants in the F1 generation were allowed to self-pollinate.
#### (b) The plants in the breeding. ___ P generation ___ are true.
The P (parental) generation refers to the original set of parents crossed. These plants are typically true-breeding, meaning they are homozygous for the traits of interest. So, the correct answer is:
The plants in the breeding. P generation are true.
#### (c) After a cross, there are three times as many tall plants as there are short plants in the ___ F2 generation ___.
According to Mendel’s laws, the F2 generation typically shows a 3:1 ratio of dominant to recessive traits due to the segregation of alleles. Therefore, the correct answer is:
After a cross, there are three times as many tall plants as there are short plants in the F2 generation.
### 2. Calculating the Ratio
A scientist repeated Mendel's experiment and obtained the following results:
- Number of purple flowers: 869
- Number of white flowers: 221
To find the ratio of purple flowers to white flowers, we divide the number of purple flowers by the number of white flowers:
[tex]\[
\text{Ratio} = \frac{\text{Number of purple flowers}}{\text{Number of white flowers}} = \frac{869}{221} \approx 3.9321
\][/tex]
So, the ratio of purple flowers to white flowers is:
[tex]\[
3.9321 : 1
\][/tex]
### Summary
1. The plants in the F1 generation were allowed to self-pollinate.
2. The plants in the breeding. P generation are true.
3. After a cross, there are three times as many tall plants as there are short plants in the F2 generation.
4. The ratio of purple flowers to white flowers is 3.9321 : 1.
