Answers to Hands-on Pg 63-64

Aim : To illustrate Mendel’s first law using coloured buttons

Colours of buttons	Number of pairs	Trait represented by buttons
Red and red	24	Tall
Red and white	53	Tall
White and white	23	Dwarf

Discussions:

1. Red
2. Gamete
3. Tall plant. Red button represent the gene for tallness which is dominant. Therefore when it is paired with a white button which is recessive, then a tall plant is produced.  A dominant gene expresses itself even when it is in the heterozygous condition.
4. The ratio of tall : dwarf is 3:1.  This is because an organism’s characteristic is determined by a pair of genes which will separate and be carried in a gamete and the dominant gene will express itself.

Conclusion :

Mendel’s first law is illustrated by separating the buttons before pairing them again which shows that a characteristic in an organism is represented by a pair of genes. The genes will separate and each gene is carried by a gamete.