Plant Biology and Classification

Binomial nomenclature assigns each organism a name consisting of two parts: the genus and the species epithet.

A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. A keystone species is often a dominant predator whose removal allows a prey population to explode and often decreases overall diversity. It includes the American alligators, beavers, bees, elephants, gopher tortoises, grizzly bears, hummingbirds, ivory tree corals, jaguars, mountain lions, mycorrhizal fungi, Pacific salmon and prairie dogs. Thus, Mycorrhiza is a keystone species.

Mucor belongs to the class zygomycetes. The members of zygomycetes bear non-motile non-flagellated gametes.

• ICBN stands for - International Code of Botanical Nomenclature. 
  
• It is the set of rules and recommendations for naming plants, fungi, and algae as the ICBN applies not only to plants, as they are now defined, but also to other organisms traditionally studied by botanists.
  

Binomial nomenclature involves a generic epithet, a specific epithet, Latin language usage, and specific formatting rules like italics or underlining. All four listed features are standard components of the system.

Nomenclature is application of correct name to plants and taxonomic rank under the rule as drawn by ICBN (International Code for Botanical Nomenclature); option A is incorrect and B is correct. Scientific names formulated in Latin language are preferred over those in vernacular languages due to restricted use and application of these names in one or two languages and non-availability of vernacular names for all known plant species; this makes option C incorrect. Scientific names are not formulated in English but in Latin because latter one is a dead language and the meanings of words are not prone to changes as is the case with English; this makes option D incorrect. Thus, the correct answer is option B.

Scientific names are derived from Latin language. This is because it is a dead language and the meanings of words are not prone to changes.

The art of naming an object is, in fact, a science called nomenclature. Binomial nomenclature is followed worldwide to identify an organism. Every organism has a scientific name, which is a combination of genus and species. Most of these names are in the Latin language. For example, the scientific name of human is Homo sapiens and that of frog is Rana tigrina.

Algae, bryophytes, pteridophytes, gymnosperms, and angiosperms are all members of the domain Eukaryota.

Thigmotropism is the growth or movement of a plant in response to touch. The telegraph plant (Codariocalyx motorius) exhibits rapid leaf movement in response to touch/vibration.

Phototactic movement is movement of organisms influenced by light. Low intensiti of light induces positive phototactic movement in algae.

Thigmonasty is the response of a plant to touch or vibration. The Venus Flytrap an insectivorous plant shows thigmonasty. When an insect lands on its trap, the tentacles present on the two curved lobes of a single leaf, rapidly close. Hence the insect gets trapped and later killed. Thus the correct answer is option C.

Nyctinasty is the rhythmic nastic movement shown by plant in response to onset of darkness. Chemonasty is the nastic movement shown by plant in response to external chemical stimuli. Antherozoids are attracted towards archegonia in a fern plant due to chemonastic movement. Thigmonasty is the nastic movement shown by plant in response to the touch. Seismonasty is the nastic movement shown by plant in response to the vibration.

Azolla pinnata is an aquatic fern, which contains a nitrogen-fixing cyanobacteria. It contains Anabaena azollae in its leaf cavities. It is an excellent biofertilizer for paddy fields because they can fix nitrogen in moist condition also.