The plant is heterozygous for green leaves. Green (G) is dominant over variegated (g).
This biology question covers important biological concepts and processes. The step-by-step explanation below helps you understand the underlying mechanisms and reasoning.
ScanSolve AI Answer
Here are the solutions to the genetics problems:
3.1.1
The plant is heterozygous for green leaves. Green (G) is dominant over variegated (g).
The genotype is $\boxed{\text{Gg}}$.
3.1.2
The plant (Gg) undergoes self-pollination (Gg x Gg).
The Punnett square for Gg x Gg is:
| | G | g |
|---|---|---|
| G | GG | Gg |
| g | Gg | gg |
The genotypic ratio is 1 GG : 2 Gg : 1 gg.
The phenotypic ratio is 3 Green (GG, Gg) : 1 Variegated (gg).
Total offspring = 64.
a) Number of plants that will have variegated leaves:
Step 1: Determine the proportion of variegated offspring (gg).
$$P(\text{gg}) = \frac{1}{4}$$
Step 2: Calculate the number of variegated plants.
$$\text{Number of variegated plants} = \frac{1}{4} \times 64 = 16$$
Expected number of plants with variegated leaves: $\boxed{\text{16}}$
b) Number of plants that will be heterozygous for green leaves:
Step 1: Determine the proportion of heterozygous offspring (Gg).
$$P(\text{Gg}) = \frac{2}{4} = \frac{1}{2}$$
Step 2: Calculate the number of heterozygous plants.
$$\text{Number of heterozygous plants} = \frac{1}{2} \times 64 = 32$$
Expected number of plants heterozygous for green leaves: $\boxed{\text{32}}$
c) Number of plants that will be homozygous:
Step 1: Determine the proportion of homozygous offspring (GG or gg).
$$P(\text{homozygous}) = P(\text{GG}) + P(\text{gg}) = \frac{1}{4} + \frac{1}{4} = \frac{2}{4} = \frac{1}{2}$$
Step 2: Calculate the number of homozygous plants.
$$\text{Number of homozygous plants} = \frac{1}{2} \times 64 = 32$$
Expected number of homozygous plants: $\boxed{\text{32}}$
2.5
Symbols: T = normal allele, t = recessive Tay-Sachs allele.
A couple are both heterozygous for Tay-Sachs (Tt x Tt).
The Punnett square for Tt x Tt is:
| | T | t |
|---|---|---|
| T | TT | Tt |
| t | Tt | tt |
The genotypic ratio is 1 TT : 2 Tt : 1 tt.
Tay-Sachs disorder is recessive, so a child with the disorder has the genotype tt.
Step 1: Determine the proportion of offspring with Tay-Sachs (tt).
$$P(\text{tt}) = \frac{1}{4}$$
Step 2: Convert the proportion to a percentage.
$$\text{Percentage chance} = \frac{1}{4} \times 100\% = 25\%$$
The percentage chance of having a child with Tay-Sachs disorder is $\boxed{\text{25\%}}$.
2.6
One in every 27 people in the population group has at least one allele for Tay-Sachs (Tt or tt).
Total sample size = 360,000 people.
Step 1: Identify the proportion of people with at least one allele for Tay-Sachs.
$$\text{Proportion} = \frac{1}{27}$$
Step 2: Calculate the expected number of people with the allele in the sample.
$$\text{Number of people with allele} = \frac{1}{27} \times 360\,000$$
$$\text{Number of people with allele} = 13\,333.33$$
Since the number of people must be a whole number, we round to the nearest whole number.
$$\text{Number of people with allele} \approx 13\,333$$
You expect $\boxed{\text{13,333}}$ people to have the allele for Tay-Sachs.
