The three-domain system was first invented in 1990. One main characteristic of the three domain method is the separation of Archaea and bacteria, previously, grouped into the single Kingdom Bacteria (or Monera). The three domains of life are as follows:
(a) Archaea
(b) Bacteria and
(c) Monera.

(i) Lion and monkeys possess the mammalian characters.
(ii) Maintaining zoological parks conserver the endangered and critically endasgered species.
(iii) The natural biosphere reserves have variety of plants. 
(iv) Ria is a good observer, enthusiastic and nature loving.

Manuals and records basically help in understanding past flora and fauna of a given area. Take an example of a thriving city. There may had been a dense forest, rich in biodiversity, where we get to see densely populated cities today. The manuals and records of that area helps us in knowing about past richness in biodiversity.
We also come to know about extinct species, through manuals and records. Some of the extinct species may be close or distant relatives of some existing species. We can develop some evolutionary relationships between them.

This is a very big world and there is huge diversity of animals and plants in this world. People of different parts of the world speak different languages. Even in a country, like India, a simple bird, like crow is known by hundreds of names. Think of a scientist's difficulty in understanding about crows in different languages. Moreover, there can be thousands of species of birds. It is practically impossible to study each and every species of plants and animals. Classification makes it easy to study living beings, by keeping them under various groups and subgroups.
So, all animals which are capable of flying and have beaks are kept under Aves. Similarly, all animals, having body hair and external ears are kept under mammalia. This makes our task to study them, far easier. An easy way to study helps us in understanding the living world in a better way. It can be said that classification definitely helps in a better and systematic study of living beings.

The scientist will first identify the family to which the plant belongs
He will further follow the given steps
(i)  Using genus key, the genus is identified.
(ii)  Using species key, identification is carried out
(iii)  As the genus is known, the species is provided now with a latinised name as per guidelines.
(iv)  Type specimen or holotype is placed in a recognised herbarium or museum.
(v) Name, description and report of the discovery is published in a reputed scientific journal.

(i)  Common name: Mustard.
(ii)  Parts of the name: First part represents the genus or generic name, while the second part represents the specific name.
(iii) They are written in Italics in order to highlight their Latin origin.
(iv) Linn written at the end of the name, is the abbreviation of the name of scientist Linnaeus, who gave the name to the plant.

An organism is said to be living, if it shows certain characteristic features that make it different from non-living things.
The following properties are defining features of a living organisms.
(i)  Growth : All living organisms show growth either by multiplication or by increase in size. Growth in living things is internal.
(ii)  Reproduction : All living things produce offsprings, possessing features similar to their parents. Thus, reproduction is essential to maintain the continuity of life on earth.
(iii)  Metabolism : It is the sum total of reactions occurring inside the body by which living things assimilate energy and use it for growth.
(iv)  Cellular Organisation : The cells are the structural and functional unit of every living organism.