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My name is Poon Cheng Moh. I have been teaching biology in SMK(P) Raja Zarina, Port Klang for 26 years. I sincerely hope that this blog on SPM Biology will be useful to both teachers and students.

Saturday, August 11, 2012

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
Red and white
White and white

  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.

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