Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.
The three out breeding devices that flowering plants have developed to encourage cross-pollination are:
i. In some species, pollen release and stigma receptivity are not synchronized that is either the pollen is released before the stigma becomes receptive or stigma becomes receptive much before the release of pollen.
ii. In some other species, the anther and stigma are placed at different positions so that the pollen cannot come in contact with the stigma of the same flower.
iii. Plants show self-incompatibility which is a genetic mechanism and prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
How have transgenic animals proved to be beneficial in:
(a) Production of biological products
(b)Chemical safety testing.
Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments? State any three reasons.
Describe the mutual relationship between fig tree and wasp and comment on the phenomenon that operates in their relationship.
Linkage or crossing-over of genes are alternatives of each other. Justify with the help of an example.
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.