Question

QUESTION 3
(a) i) Why did Mendel select the garden pea for his experiment?
ii) List any three features of garden pea with their dominant and recessive traits.
iii) Give two examples of mutation.
[5]
(b) i) State Mendel's law of independent assortment.
ii) A homozygous Tall plant (T) bearing red coloured (R) flowers is crossed with a
homozygous Dwarf plant (t) bearing white flowers (r).
1. Give the genotype and phenotype of the F1 generation.
2. Give the possible combination of the gametes that can be obtained from the F1
hybrid.
3. Give the dihybrid ratio and the phenotype of the offspring of the F2 generation
(5]
when two plants of Fl generation above are crossed.
ro​

Answer 1

Answer:

(a)

i)Mendel selected garden pea plant for his experiments because of the following characteristics:

• The flowers of this plant are bisexual. 
• They are self-pollinating, and thus, self and cross pollination can easily be performed. 
• The different physical characteristics were easy to recognise and study. 
• They have a shorter life span and are the plants are easier to maintain.

ii) Characters Dominate Recessive

1)Flower Colour Purple White

2)Seed Colour Yellow Green

3)Seed Shape Round Wrinkled

iii) Cystic fibrosis & Sickle cell anemia

(b)

i) Mendel's law of independent assortment states that genes do not influence each other with regard to the sorting of alleles into gametes: every possible combination of alleles for every gene is equally likely to occur.

ii) 1)The genotype of the homozygous dominant plant is TTRR, thus the gametes produced by this plant will contain TR genes. The genotype of the homozygous recessive plant is ttrr, thus the gametes produced by this plant will contain tr genes. Thus, the genotype of F1 generation will be TtRr. The phenotype of F1 generation will be tall plant with red coloured flowers.

2)The possible combinations of gametes that can be obtained from F1 hybrid plants are, 

TR: Tall and Red

Tr: Tall and White

tR: Dwarf and Red

tr: Dwarf and White

3)From Punnett square: F2 gives a phenotypic ratio of 9 : 3 : 3 : 1