Question 4:
Table 1 shows genotype and phenotype of human ABO blood group inheritance.
(a)(i) Complete genotype and phenotype in Table 1. [2 marks]
(ii) Explain why the phenotype of blood group AB is expressed when the genotype is IAIB. [1 mark]
(b) Diagram 4 shows a schematic diagram of a cross of human earlobe shape inheritance.
State the probability of getting a child with attached earlobe.
Show your calculations.
Probability : ………………………….
[2 marks]
(c) Compare the inheritance in Table 1 and the inheritance in Diagram 4.
Similarity : ……………………………
Difference : …………………………..
[2 marks]
Answer:
(a)(i)
(a)(ii)
Both are dominant / codominant alleles
(b)
$$ \begin{aligned} & \text { P1: } \frac{2}{4} \times 100 \% / / \frac{1}{2} \times 100 \% \\ & \text { P2: } 50 \% \end{aligned} $$
OR
$$ \begin{aligned} & \text { P1: } \frac{2}{4} / / \frac{1}{4}+\frac{1}{4} / / 1(1+1) \\ & \text { P2: } 0.5 \end{aligned} $$
(c)
SIMILARITIES
P1: Both are monohybrid inheritance / involving only one trait
P2: Follow Mendel’s Law 1 / Segregation (during gamete formation)
Any one of similarities & one differences
Table 1 shows genotype and phenotype of human ABO blood group inheritance.
(a)(i) Complete genotype and phenotype in Table 1. [2 marks]
(ii) Explain why the phenotype of blood group AB is expressed when the genotype is IAIB. [1 mark]
(b) Diagram 4 shows a schematic diagram of a cross of human earlobe shape inheritance.
State the probability of getting a child with attached earlobe.
Show your calculations.
Probability : ………………………….
[2 marks]
(c) Compare the inheritance in Table 1 and the inheritance in Diagram 4.
Similarity : ……………………………
Difference : …………………………..
[2 marks]
Answer:
(a)(i)
(a)(ii)
Both are dominant / codominant alleles
(b)
$$ \begin{aligned} & \text { P1: } \frac{2}{4} \times 100 \% / / \frac{1}{2} \times 100 \% \\ & \text { P2: } 50 \% \end{aligned} $$
OR
$$ \begin{aligned} & \text { P1: } \frac{2}{4} / / \frac{1}{4}+\frac{1}{4} / / 1(1+1) \\ & \text { P2: } 0.5 \end{aligned} $$
(c)
SIMILARITIES
P1: Both are monohybrid inheritance / involving only one trait
P2: Follow Mendel’s Law 1 / Segregation (during gamete formation)
Any one of similarities & one differences