Chi Square Practice Problems, Schemes and Mind Maps of Biology

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AP Biology Name: __________________ Chi Square Practice Problems Date: ____________ Per: ___ Chi-square is a statistical tool that helps us to decide if the observed ratio is close enough to the expected ratio to be acceptable. Chi-square analysis can be used in any area, not just genetics. Whenever you have to determine if an expected ratio fits an observed ratio, you can use the Chi-square. Χ^2 = Σ (O-E)^2 E Chi Square Significance Table Degrees of Freedom (n) 5% Probability Value (P) 1 3. 2 5. 3 7. 4 9.

1. In peas, yellow seeds (A) are dominant over green (a) seeds. In a cross between two plants both heterozygous for seed color, the following was observed: Yellow = 4400 Green = 1624 Does the data fit the predicted phenotypic ratio? Phenotype Observed (O) Expected (E) O-E (O-E)^2 (O-E)^2 E Totals
2. In peas, smooth seeds (R) are dominant over wrinkled (r) seeds. In the P generation, a plant homozygous for smooth seeds is crossed with a plant with wrinkled seeds. The resulting F 1 plants are crossed. The seeds of the observed F 2 generation were: Smooth = 5474 Wrinkled = 1850 Does the data fit the predicted phenotypic ratio? Phenotype Obseved (O) Expected (E) O-E (O-E)^2 (O-E)^2 E

6. Color blindness is a sex-linked trait in Bombats. A female who is a carrier of the color blind allele mates with a male who is color blind. The phenotypes of their offspring are: Normal female = 132 Color blind female = 124 Normal male = 126 Color blind male = 136 Does the data fit your predicted phenotypic ratio? Phenotype Obseved (O) Expected (E) O-E (O-E)^2 (O-E)^2 E Totals
7. In cats, fur color is determined by the codominant, sex-linked alleles: black (B) and orange (O). A calico female (XBXO) is bred (many times) with a black male (XBY). They produce the following offspring: Black female = 78 Calico female = 65 Black male = 81 Orange male = 45 Does the data fit your predicted phenotypic ratio? Phenotype Obseved (O) Expected (E) O-E (O-E)^2 (O-E)^2 E