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12. Tatuo Aida investigated the genetic basis of color variation in the medaka (Aplocheilus latipes), a small fish found in Japan (T. Aida. 1921. Genetics 6:554–573). Aida found that genes at two loci (B, b and R, r) determine the color of the fish: fish with a dominant allele at both loci (B_ R_) are brown, fish with a dominant allele at the B locus only (B_ rr) are blue, fish with a dominant allele at the R locus only (bb R_) are red, and fish with recessive alleles at both loci (bb rr) are white. Aida crossed a homozygous brown fish with a homozygous white fish. He then backcrossed the F? with the homozygous white parent and obtained 260 brown fish, 253 blue fish, 249 red fish, and 238 white fish. 1. a. Give the genotypes of the backcross progeny. 2. b. Use a chi-square test to compare the observed numbers of backcross progeny with the number expected. What conclusion can you make from your chi-square results? 3. c. What results would you expect for a cross between a homozygous red fish and a white fish? 4. d. What results would you expect if you crossed a homozygous red fish with a homozygous blue fish and then backcrossed the F? with a homozygous red parental fish?

          12. Tatuo Aida investigated the genetic basis of color variation in the medaka (Aplocheilus latipes), a small fish found in Japan (T. Aida. 1921. Genetics 6:554–573). Aida found that genes at two loci (B, b and R, r) determine the color of the fish: fish with a dominant allele at both loci (B_ R_) are brown, fish with a dominant allele at the B locus only (B_ rr) are blue, fish with a dominant allele at the R locus only (bb R_) are red, and fish with recessive alleles at both loci (bb rr) are white. Aida crossed a homozygous brown fish with a homozygous white fish. He then backcrossed the F? with the homozygous white parent and obtained 260 brown fish, 253 blue fish, 249 red fish, and 238 white fish.
1. a. Give the genotypes of the backcross progeny.
2. b. Use a chi-square test to compare the observed numbers of backcross progeny with the number expected. What conclusion can you make from your chi-square results?
3. c. What results would you expect for a cross between a homozygous red fish and a white fish?
4. d. What results would you expect if you crossed a homozygous red fish with a homozygous blue fish and then backcrossed the F? with a homozygous red parental fish?

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12. Tatuo Aida investigated the genetic basis of color variation in the medaka (Aplocheilus latipes), a small fish found in Japan (T. Aida. 1921. Genetics 6:554–573). Aida found that genes at two loci (B, b and R, r) determine the color of the fish: fish with a dominant allele at both loci (B R) are brown, fish with a dominant allele at the B locus only (B rr) are blue, fish with a dominant allele at the R locus only (bb R) are red, and fish with recessive alleles at both loci (bb rr) are white. Aida crossed a homozygous brown fish with a homozygous white fish. He then backcrossed the F? with the homozygous white parent and obtained 260 brown fish, 253 blue fish, 249 red fish, and 238 white fish.
1. a. Give the genotypes of the backcross progeny.
2. b. Use a chi-square test to compare the observed numbers of backcross progeny with the number expected. What conclusion can you make from your chi-square results?
3. c. What results would you expect for a cross between a homozygous red fish and a white fish?
4. d. What results would you expect if you crossed a homozygous red fish with a homozygous blue fish and then backcrossed the F? with a homozygous red parental fish?

Added by Jasmine M.

Biology for AP Courses

Julianne Zedalis, John Eggebrecht

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Solved by Expert Jenny Wu

10/26/2023

Step 1

The initial cross is between a homozygous brown fish (BBRR) and a homozygous white fish (bbrr). The F1 generation will all be heterozygous (BbRr). Show more…

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12. Tatuo Aida investigated the genetic basis of color variation in the medaka (Aplocheilus latipes), a small fish found in Japan (T. Aida. 1921. Genetics 6:554-573). Aida found that genes at two loci (B, b and R, r) determine the color of the fish: fish with a dominant allele at both loci (B_ R_) are brown, fish with a dominant allele at the B locus only (B_ rr) are blue, fish with a dominant allele at the R locus only (bb R_) are red, and fish with recessive alleles at both loci (bb rr) are white. Aida crossed a homozygous brown fish with a homozygous white fish. He then backcrossed the F₁ with the homozygous white parent and obtained 260 brown fish, 253 blue fish, 249 red fish, and 238 white fish. a. Give the genotypes of the backcross progeny. b. Use a chi-square test to compare the observed numbers of backcross progeny with the number expected. What conclusion can you make from your chi-square results? c. What results would you expect for a cross between a homozygous red fish and a white fish? d. What results would you expect if you crossed a homozygous red fish with a homozygous blue fish and then backcrossed the F₁ with a homozygous red parental fish?

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