Question

In a cross between individuals homozygous for (a, b) and wild type (+ +), 700 out of 1000 individuals were of parental type. Then the distance between a and b is

• A. 70 map unit
• B. 35 map unit
• C. 30 map unit
• D. 15 map unit

Answer 1

The correct option is C 30 map unit

The percentage of recombinants formed by F${}_1$ individuals is the measure of distance between genes under study. The recombinants percentage is taken as the distance in centimorgans (cM); 1% recombinants means the genes are present 1cM apart. Since, the recombinants percentage in question is 30% (700 out of 1000 individuals were of parental type and hence 300 were recombinants), the a and b loci 30 map unit apart. Thus, the correct option is C.