If pink snapdragons of the f1 hybrids (rw) are crossed with red snapdragons of the parent plant (rr), what will be the ratio of flowers produced in 40 offspring?

a. 30 pink flowers, 10 red flowers
b. 20 pink flowers, 20 red flowers
c. 10 pink flowers, 30 white flowers

The answer is B. 20 pink flowers, 20 red flowers.


Let's cross the parents:
Parents:             RW      x       RR
Offspring:      RR     RR      RW     RW

So, 2 out of 4 (with possibility P1 = 2/4 = 1/2) are the red snapdragons (RR) and 2 out of 4 (with possbility P2 = 2/4 = 1/2) are pink snapdragons (RW).

- Among 40 offspring, there will be 20 pink flowers:
40 offspring · P1 = 40 · 1/2 = 20

- Among 40 offspring, there will be 20 red flowers:
40 offspring · P2 = 40 · 1/2 = 20