Question

1) When orchid fanciers reproduce orchids they call it meristeming. Do you suspect that they are producing orchids via sexual or asexual reproduction? How do you suspect they are producing more orchids?

2)Describe the process of rhizobial infection and nodule development in a legume root. When legumes are grown in soil that has excess nitrogen available it does not make root nodules. Why not?

Answer 1

1) Meristems are embryonic tissue. This type of tissue is responsible for and are the main area for cell division. Orchid growers produce new orchids through the method of meristeming. In this method, the part from apical cells which are present at the shoot tips of orchid are removed. The part which has been removed further continues to grow and developed as new plants. The new orchids which are produced by this method is called mericlone.

2) Nodules in legumes are required for nitrogen fixation. Nodules are formed when bacteria of the genus rhizobium infects the root of the legume plants, nodule formation happened, This bacteria are free living and living in a soil. However, when they are coming in contact with root hair of the legumes, they can form a symbiotic relation wih the plant. During, this infection period, bacterias are get attached with the curly hair root and creats an infection pocket. A trancellular tube like structure is next formed from this infectio pocket. This tube is called infection thread and bacterias can colonize on this thread. This read continues to gorw until it reaches the primordium of nodule. Rhizobium thus can reach the place and able to fix nitrogen.

when there is excess soil in nirogen, nodules are not formed as plants don't require the beneficial effect of symbiosis to get nitrogen.