2 test Chi squared Pronounced Ky squared rhymes
- Slides: 6
2 test (Chi squared) Pronounced “Ky squared” - rhymes with sky © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 Gregor Mendel
The parental cross Mendel crossed some pure breeding pea plants grown from yellow, round seeds with some pure breeding plants grown from green, wrinkled seeds. All the seeds produced were yellow and round Let Y = yellow, y = green Let R = round, r = wrinkled Parental phenotype Parental genotype Gametes Yellow, round X Green, wrinkled YYRR X YR yyrr yr F 1 genotype Yy. Rr F 1 phenotype Yellow, round © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 Observed results match expected results
The F 1 cross He then self fertilised (“selfed”) the plants grown from these F 1 seeds and got 144 seeds • 86 yellow, round seeds • 26 yellow, wrinkled seeds • 24 green, round seeds • 8 green, wrinkled seeds F 1 phenotype F 1 genotype Gametes Yellow, round X Yellow, round Yy. Rr YR; Yr; y. R; yr © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 X Yy. Rr YR; Yr; y. R; yr
The F 1 cross He then selfed the plants grown from these F 1 seeds and got 144 seeds • 86 yellow, round seeds • 26 yellow, wrinkled seeds • 24 green, round seeds • 8 green, wrinkled seeds YR thea IAre need observed statistical results close test! enough ? Yr y. R yr YR YYRr Yy. RR Yy. Rr Yr YYRr YYrr Yy. Rr Yyrr y. R Yy. Rr yy. RR yy. Rr yr Yy. Rr Yyrr yy. Rr yyrr F 2 phenotype 9 Yellow, round 3 Green, round © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 3 Yellow, wrinkled 1 Green, wrinkled
Using 2 test Observed number (O) 86 26 24 8 144 Expected ratio 9 3 3 1 16 Expected number (E) 81 27 27 9 O-E +5 -1 (O - E)2 25 (O – E)2 / E 0. 31 Σ (O – E)2 / E 0. 79 2 0. 79 © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 -3 9/16 3/16 144 1/16 xxx 144 1 9 == 27 =81 9 0. 04 0. 33 -1 1 0. 11
Using the table of Degrees of freedom 0. 1 0. 05 0. 01 0. 001 1 2. 71 3. 84 6. 64 10. 83 2 4. 60 5. 99 9. 21 13. 82 3 6. 25 7. 82 11. 34 16. 27 4 7. 78 9. 49 13. 28 18. 46 2 values Probability Degrees of freedom = Number of classes - 1 = 4– 1 =3 2 is 0. 79 which is less than 6. 25 So, the probability is greater than 0. 1 There is no significant difference between observed and expected results © Teachable and Toby Tufton. Some rights reserved. http: //teachable. net/res. asp? r=858 Yellow round Yellow wrinkled Green round Green wrinkled
