Question

What is mutualism? Mention any two examples where the organisms involved are commercially exploited in agriculture.

OR

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

Answer 1

1. Mutualism is the relationship between two organisms where both organisms are benefited in terms of food, shelter and substratum for attachment.

Two examples:

1. Mycorrhizae are the mutualistic relationship between fungi and roots of higher plants. The fungus helps in mineral nutrition of the plant with which they are associated and obtains, in turn, carbohydrates from the plant.
2. Nitrogen-fixing bacteria, Rhizobium, live in the root nodules of legumes where the bacterium derives nutrition from the host plant but fixes the atmospheric nitrogen and makes it available to the plants.

OR

Ex situ conservation is the conservation of selected rare plants or animals in places outside their natural homes. Ex situ conservation of biodiversity has been employed in

1. Gene banks: These are the institutes which maintain stocks of viable seeds, live growing plants, tissue culture and frozen germplasm with the whole range of genetic variability.
2. Cryopreservation: Cryopreservation can maintain tissue culture, embryos, gametes, animal cells or tissues. Endangered organisms are being cryopreserved so that they can be revived to help in conservation.
3. Orchards: Plants with recalcitrant seeds are grown in orchards where all possible strains and varieties are maintained.
4. Tissue culture: It is carried out through callus formation, embryoids, pollen grain culture and shoot tip culture in plants which are either seedless, have recalcitrant seeds, variable seed progeny or where clones are to be maintained.