colour follows standard Mendelian dihybrid ratio Sok Ee Lee and Kiah Woon Low Hwa Chong Institution Introduction Fig 1 unknown F1 cross showing two characters antenna shape and eye ID: 190793
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Slide1
Inheritance of antenna shape and eye
colour
follows standard
Mendelian
dihybrid
ratio
Sok Ee, Lee and Kiah Woon, LowHwa Chong Institution
Introduction
Fig. 1.
unknown F1 cross showing two characters: antenna shape and eye colourOur group sets out to conduct several stimulated crosses to find out which is the dominant trait for each character
Results and Discussion
Conclusion
Hypothesis
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. 3.
Preliminary cross 2 showing that parents with knobbed antenna gives offspring with knobbed antenna onlyEvidence 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.
Fig. 4. Conclusive cross showing that parents with long antenna and yellow eyes can give offspring of all 4 different phenotypes
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.
Methodology
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.
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.
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
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.