Nitrogen-fixation in root nodules of Alnus is brought about by
Bradyrhizobium
Clostridium
Frankia
Azorhizobium
C.
Frankia
Nitrogen is the most critical element. The atmosphere is the greatest reservoir of nitrogen. Molecular nitrogen cannot be utilized directly by plants. It has to be fixed or converted into compounds prior to utilization, Symbiotic nitrogen fixation is accomplished by Rhizobium species, which occurs on the roots of leguminous plants. Certain non-leguminous plants also form nodules to fix nitrogen. The best known example in temperate region is alder (Alnus sp.). The bacteria involved in nodule formation is an Actinomycetes, the Frankia.
Clostridium is anaerobic, saprotrophic, free-living nitrogen-fixing bacteria.
Bradyrhizobium is symbiont in plants of parasponia and soyabean.
The Azorhizobium forms both stem and root nodules in Sesbania (aquatic plant).
Darwin’s finches are an excellent example of
Adaptive Radiation
Seasonal migration
Brood parasitism
Connecting links
During the propagation of a nerve impulse, the action potential results from the movement of
K+ ions from extracellular fluid to intracellular fluid
Na+ ions from intracellular fluid to extracellular fluid
K+ ions from intracellular fluid to extracellular fluid
Na+ ions from extracellular fluid to intracellular fluid
In mitochondria, enzyme cytochrome oxidase is present in
Outer membrane
Perimitochondrial space
Inner Membrane
Matrix
In which one of the following, the male and female gametophytes don’t have free-living independent existence?
Pteris
Funaria
Polytrichum
Cedrus
