Inheritance of antenna shape and eye colour follows standard Mendelian dihybrid ratio

1. Inheritance of antenna shape and eye colour follows standard Mendeliandihybrid ratio SokEe, Lee and Kiah Woon, Low Hwa Chong Institution Introduction Results and Discussion Fig. 2. Preliminary cross 1 showing that parents with yellow eyes can give offspring with red eyes Evidence points to the red eyes trait as recessive Fig. 1. unknown F1 cross showing two characters: antenna shape and eye colour Our group sets out to conduct several stimulated crosses to find out which is the dominant trait for each character Fig. 4. Conclusive cross showing that parents with long antenna and yellow eyes can give offspring of all 4 different phenotypes Hypothesis Fig. 3. Preliminary cross 2 showing that parents with knobbed antenna gives offspring with knobbed antenna only Evidence points to the knobbed antenna trait as recessive but it is not conclusive. This motivates us to conduct a third conclusive cross – see Fig. 4. The inheritance of antenna shape and eye colur follows the standard Mendelian inheritance – a double heterozygous cross is expected to give a 9:3:3:1 ratio. Methodology From Fig. 2 and 3, we could determine with reasonable confidence that red eye trait is recessive for eye colour character and the knobbed antenna trait is recessive for antenna shape. Choosing parents with long antenna and yellow eyes in a hope to find double heterozygotes, we have a cross shown in Fig. 4 that give the observed numbers. Chi-Square Test shows that the observed results do not differ significantly from the expected ratio of 9:3:3:1. First, conduct a few preliminary crosses in which we will look at one character at a time during the cross to determine which is the dominant or recessive trait of that character. Having determined the dominant/recessive trait, we would trial a few crosses to find double heterozygotes to conduct the conclusive cross that gives all 4 phenotypes in the offspring Fig. 5. Chi-Square Test results show that the observed ratio do not differ significantly from the expected ratio 9:3:3:1 of a standard dihybrid cross. Conclusion The inheritance of antenna shape and eye colour follows the standard Mendelian inheritance – a double heterozygote cross is gave a 9 long antenna, yellow eyes : 3 long antenna, red eyes : 3 knobbed antenna, yellow eyes : 1 knobbed antenna, red eyes ratio.