Final answer:
Among the plants listed, the ginger rhizome is primarily a reproductive organ, while the yam tuber, cassava tuber, and Irish potato tuber are both reproductive and storage parts. The ginger rhizome is not a true tuber as it's mainly for reproduction.
Step-by-step explanation:
The parts of the plants mentioned - yam tuber, cassava tuber, ginger rhizome, and Irish potato tuber - are specialized structures involved in both reproduction and storage of nutrients. In these plant structures, storages of starch and other nutrients enable the plant to survive in hostile above-ground climates by sprouting new growth when conditions improve. The exception among the options provided is the ginger rhizome, which is not a true tuber but a modified stem that can give rise to new plants; it is mainly a reproductive organ rather than a storage one. While all mentioned structures can give rise to new plants, tubers like the Irish potato additionally have a high capacity for nutrient storage, particularly starch, due to their numerous starch-storing cells called amyloplasts.