5. Let the allele be represented by the letter D (dominant) and d (recessive) - not sure if there was any other information about what the trait is
Your table has to look like this:
Homozygous dominant Genotype is DD Phenotype is Dominant trait
Heterozygous Genotype is Dd Phenotype is dominant trait
Homozygous recessive Genotype is dd Phenotype is recessive trait
6. Punnet square
Parents are True breeding black (BB) and True breeding white (bb)
B B
b Bb Bb
b Bb Bb
You can imagine the squares around that. So, all the offspring would be Bb (heterozygous) so all would phenotypically look black.