Someone please help me with Punnett square

1. Phenotype ratio = 3:1

Genotype ratio = 1:2:1

2. Phenotype ratio = 4:0

Genotype ratio = 4:0

3. Phenotype ratio = 1:1

Genotype ratio = 1:1

Explanation:

According to this question, a gene coding for tallness is involved. The allele for tallness (T) is dominant over the allele for shortness (t). The phenotype and genotype ratio of each parental combinations is given in the attached punnet square.

1. Tt × Tt

In this cross, both parents (Tt) will produce T and t gametes. Using this in a punnet square, the offsprings will be as follows: TT, Tt, Tt, and tt. Hence, The phenotype ratio is 3 tall: 1 short while genotype ratio is 1(TT): 2(Tt) : 1(tt).

2. TT × tt

In this cross, TT will produce T gametes while tt will produce t gametes. Using this in a punnet square, all offsprings will be heterozygous "Tt". Hence, The phenotype ratio is 4 tall: 0 short while genotype ratio is 4 (Tt) : 0 (tt).

3. tt × Tt

In this cross, tt will produce t gametes while Tt will produce T and t gametes. Using this in a punnet square, the following offsprings will result: Tt, Tt, tt and tt. Hence, The phenotype ratio is 1 tall: 1 short while genotype ratio is 1(Tt) : 1(tt).

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.