Genetics Answers

In a certain plant, both purple x purple and purple x blue produce purple and blue coloured progeny, but blue x blue gives rise only to blue.

2.1. What does this tell you about the genotypes of blue- and purple-flowered plants [5 marks]

2.2. Which gene is dominant

In peas, a gene for tall plants (T) is dominant over its allele for short plants (t). The gene for smooth peas (S) is dominant over its allele for wrinkled peas (s). The genes are not linked. Determine both phenotypic and genotypic ratios for the results of each of the following crosses:

3.2. homozygous tall wrinkled x short heterozygous smooth.                 [26 marks]

These drugs interfere with DNA synthesis in treated cells. How could this action halt mitosis?

In a particular species of plant, tall is dominant to short, and orange petals are dominant to the recessive white colour. Use T and t to symbolize the alleles for height, and F and f to symbolize the alleles for flower colour. A homozygous tall white flower is crossed with a flower heterozygous for both traits.

1.1 List the genotypes of the parents. 

In peas, a gene for tall plants (T) is dominant over its allele for short plants (t). The gene for smooth peas (S) is dominant over its allele for wrinkled peas (s). The genes are not linked. Determine both phenotypic and genotypic ratios for the results of each of the following crosses:

3.4. heterozygous tall homozygous smooth x short wrinkled.                 [26 marks]

In peas, a gene for tall plants (T) is dominant over its allele for short plants (t). The gene for smooth peas (S) is dominant over its allele for wrinkled peas (s). The genes are not linked. Determine both phenotypic and genotypic ratios for the results of each of the following crosses:

3.3. short heterozygous smooth x heterozygous tall wrinkled.                 [26 marks]