Biology student's notes on a genetics problem involving fish fin inheritance, featuring a hand-drawn Punnett square analysis.

a. The dominant phenotype is having two back fins.
b. The recessive phenotype is having a single back fin.
c. The two possible genotypes for each adult fish are BB (homozygous dominant) or Bb (heterozygous).
d. 4 baby fish have the dominant phenotype (two fins). 2 baby fish have the recessive phenotype (single fin).
e. Punnett Square 1 (if parent is BB):
| | B | B |
|-----|-----|-----|
| B | BB | BB |
| B | BB | BB |

Punnett Square 2 (if parent is Bb):
| | B | b |
|-----|-----|-----|
| B | BB | Bb |
| b | Bb | bb |