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
Darwin’s finches are an excellent example of
In which one of the following, the male and female gametophytes don’t have free-living independent existence?
In Pteris (also Dryopteris), the spore germinates to produce the prothallus. The prothallus is a small, green, flat, surface loving, thallus-like object. It is monoecious and bears sex organs on the ventral side. The antheridia (male sex organs) arise among the rhizoids towards the posterior side of the prothallus and are emergent. The archegonia develop in central cushion behind the apical notch. In these plants, o male and female gametophytes do not have free-living independent existence.
All species of Polytrichum are dioecious. The antheridia and archegonia are borne on different gametophore. The plant body is an erect leafy shoot but is not the entire gametophyte.
The leafy shoot arises from protonema (the juvenile stage). The leafy gametophore of Funaria reproduces sexually by the formation of antheridia and archegonia. The antheridia are formed at the summit of a relatively small, thin, leafy shoot, which develops first. The female branch arises later as a lateral outgrowth from the base of parent male shoot.
Nitrogen-fixation in root nodules of Alnus is brought about by
In mitochondria, enzyme cytochrome oxidase is present in