Chromosome theory, linkage and crossing over
- Frequency of recombination between gene pairs on same chromosome as a measure of the distance between genes to map their position on chromosome, was used for the first time by Answer: 4. Alfred Sturtevant Key idea: Alfred Sturtevant, a student of T. H. Morgan, used the frequency of recombination between gene pairs... 1
- The recombination frequency between the genes a & c is 5%, b & c is 15%, b & d is 9%, a & b is 20%, c & d is 24% and a & d is 29%. What will be the sequence of these genes on a linear chromosome ? Answer: 1. a, c, b, d Key idea: Higher recombination frequency means a greater distance between genes. The farthest pair sits at the ends. T... 1
- Experimental verification of the chromosomal theory of inheritance was done by : Answer: 4. Morgan Sutton and Boveri proposed the chromosomal theory of inheritance. Its experimental verification was done by Thomas Hunt Mo... 1
- The frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes was explained by : Answer: 3. Alfred Sturtevant Key idea: Alfred Sturtevant used recombination frequency as a measure of the distance between genes. Morgan dis... 1
- What map unit (Centimorgan) is adopted in the construction of genetic maps ? Answer: 3. A unit of distance between genes on chromosomes, representing 1% cross over. One map unit (centimorgan) is the distance between g... 1
- Select the *correct* statement : Answer: 3. Punnett square was developed by a British scientist. The Punnett square, a tool to show gamete combinations in a cross, was devis... 1
- The mechanism that causes a gene to move from one linkage group to another is called Answer: 2. translocation A gene moves from one linkage group (chromosome) to another by translocation, the transfer of a chromosome segment... 1
- In a testcross involving F_1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates : Answer: 3. The two genes are linked and present on the same chromosome. In a testcross with an F₁ dihybrid, independent assortment gives 1:1... 1