Summative Practice Chapter 11 – Question 1 (Form 5 Biology Textbook Exercise and Answer)

Question 1:
Figure 1 shows a cross between two pea plants, X and Y. If:


(a) State the phenotypes of parental plants X and Y.

(b) Complete the gamete genotypes produced by each parent, and phenotypes in F₁ generation in Figure 1.

(c) Table 1 shows the genotypes of F₂ generation after F₁ was crossed with another F₁ generation. The total number of F2 progenies was 16.


(i) State the probability of the pea plant in F₂  generation with purple flower and constricted pod.
(ii) State the probability of the pea plant in F₂ generation with purple flower and inflated pod.
(iii) In Table 1, circle the genotypes of pea plant in F₂ generation with white flower and inflated pod. Then, determine the probability of F₂ generation for the phenotypes.

(d) State the phenotypic ratio of the progeny in F₂ generation.


(e) Based on Figure 1 and Table 1, state Mendel’s Second Law.

Answer:
(a)
X: Purple flower, constricted pod
Y: White flower, inflated pod

(b)(i)
X: Ps
Y: pS

(b)(ii) All purple flower, inflated pod

(c)(i) 3/16
(c)(ii) 9/16

(c)(iii)


Probability 3/16

(d) 9:3:3:1

(e) During gamete formation, each member of a pair of allele can combine at random with any member from another pair of alleles.