Plant Biology and Classification

Cuscuta (dodder) is a well-known parasitic plant that lacks chlorophyll and derives its nutrients from a host plant.

Balanophora is a total root parasite because it sucks sugars, minerals and also water from the roots of host plants like cabbage etc for its survival, in turn, harming the host.

A bacteria or fungi that lives within in a plant within the intercellular spaces, tissue cavities, or vascular bundles without harming the host is called as endophytes. They often benefit the host.

Legume family plants (Fabaceae), including pulses referred to as 'dal' in Indian languages, form well-known symbiotic relationships with nitrogen-fixing bacteria (Rhizobium) in root nodules. This mutualistic relationship provides plants with nitrogen while bacteria receive carbohydrates.

A.Nepenthes - It is an insectivorous plant.

The original scientific names were taken from Latin and Greek languages. New names are now derived either from Latin language or are latinised. This is because Latin language is dead and therefore, it will not change in form or spellings with the passage of time.

Hierarchy of categories is the classification of organisms in a definite sequence of categories(taxonomic categories) in a descending order starting from kingdom and reaching upto species or an ascending order from species of kingdom.

In binomial nomenclature, the first or generic word starts with a capital letter while the second word or specific epithet starts with a small letter. The name of taxonomist appears after the specific epithet, i.e., at the end of the biological name and is written in abbreviated form, e.g., Ficus benghalensis L., indicates that this species was first described by Linnaeus.

Taxon is a unit of classification which may represent any level of grouping of organisms based on certain easily observable common characteristics. Mayr $(1964)$ has defined taxon to be a taxonomic group of any rank that is sufficiently distinct to be worthy of being assigned to a definite category.

Nitrogen fixation is a process in which nitrogen ($N _2$) in the atmosphere is converted into ammonium ($NH _4^+$). Nitrogen fixation, natural and synthetic, is essential for all forms of life because nitrogen is required to biosynthesize basic building blocks of plants, animals and other life forms, e.g., nucleotides for DNA and RNA and amino acids for proteins. 

• Ulothrix is a genus of filamentous green algae which are found in marine and fresh waters habitats.
  
• They have a single girdle-shaped or band-shaped chloroplast near the peripheral region of the cytoplasm (near the cell wall).
  
• So, the correct answer is 'Girdle-shaped'.

• The chloroplast is a discoid plastid which contains chlorophyll (green pigment) within the thylakoid membranes of the organelle.
  
• This organelle is present in the green parts of plants where photosynthesis takes place.
  
• It is the main site of synthesis of glucose by the process called photosynthesis.
  
• The chlorophyll pigment captures the sunlight and converts it into chemical energy and thus, helps in the process of photosynthesis.
  
• So, the correct answer is 'Discoid'.

Rauwolfia serpentina (Indian snakeroot) belongs to the family Apocynaceae. The spelling in option D has a minor typo (Apocyanaceae instead of Apocynaceae) but is clearly the intended answer. This plant is the source of reserpine, an important alkaloid used for hypertension.

(b) Atropa belladonna is obtained from root. They contain atropine alkaloid, which is widely used for dilating the pupil of eye during testing It also a analgesic.