Linkage or crossing-over of genes are alternatives of each other. Justify with the help of an example.
Linkage is the tendency for two or more non-allelic genes to be inherited together, because they are located more or less closely on the same chromosome.
Crossing over is the process by which two homologous chromosomes pair up and exchange sections of the coiled DNA.
If linkage is high the crossing over will be low.
If linkage is less the crossing over will be more.
In Drosophila a yellow bodied white eyed female was crossed with brown bodied red eyed male, F1 progeny produced and intercrossed the F2 phenotypic ratio of Drosophila deviated significantly from Mendel’s 9:3:3:1, the genes for eye colour & body colour are closely located on the ‘X’ chromosome showing high linkage & therefore inherited together, recombinants were formed due to crossing over but at low percentage.
Describe the mutual relationship between fig tree and wasp and comment on the phenomenon that operates in their relationship.
How have transgenic animals proved to be beneficial in:
(a) Production of biological products
(b)Chemical safety testing.
With the help of one example, explain the phenomena of co-dominance and multiple allelism in human population.
Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.
Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.
Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments? State any three reasons.
