Question

Describe the two kingdom classification !

expecting quality answers ! :))

Answer 1

Hi dear !

→Two kingdom classification was given by Carolus von Linnaeus.

→It includes plants and animals.

→He has grouped them together.

→This system was used till very recent time.

→Major drawback to this classification is it doesn't differenciate between :-

★Eukaryotes and Prokaryotes

★Unicellular and Multicellular

★Photosynthetic and Non - Photosynthetic

→Although this classification was easily to understand but there exists a large number of organisms which doesn't fall in this catogery.

→And this was the reason that it was found inappropriate and hence was discarded.

Answer 2

This system of classification is the oldest. It was suggested by Carolus Linnaeus in 1758. He divided the Living World (organisms) into two kingdoms: Plantae for plants and Animalia for animals. This was reasonable in his time, because the familiar plants and animals looked clearly different. The plants were stationary, they did not eat, but seemed to need only water for growth. Animals could move around and they had to eat plants or other animals to keep alive. At cellular level, cell wall surrounded a plant cell and not an animal cell. Bacteria were placed in the plant kingdom because of their rigid cell walls. Unicellular eukaryotes with chloroplasts were considered plants.Fungi were regarded aberrant plants as they were sedentary and had cell but lacked green pigment. Unicellular eukaryotes that moved and ingested food-protozoans-were placed among animals. Unicellular eukaryotes, such as Euglena, which moved photosynthetic found place in both plant and animal kingdoms.

More differences revealed by a careful study of plants and animals are discussed below-

KINGDOM PLANTAE

 The original plant kingdom included bacteria, fungi, algae, liverworts, mosses, ferns, conifers and flowering plants. The plants have the following distinguishing features:

1-Form, Size and Symmetry. The overall form and size is generally variable in plants. However, the shape of certain organs, such as leaves, flowers and fruits, is nearly constant. Plant body is usually asymmetrical due to its irregular form.

2-Movement and Locomotion. Plants, if at all move their parts, do so very slowly because they lack muscles. Plants are mostly rooted and incapable of locomotion.

3-Growth. Growth in plants occurs at the growing points only. It is unlimited and continues as long as plant live.

4-Reproduction. Plants seek services of external agencies, such as air, water and insects, in sexual reproduction. Asexual reproduction and regeneration are widespread in plants.



KINGDOM ANIMALIA
 
The original animal kingdom included protozoans, sponges, jellyfishes, worms, insects, crabs , spiders, snails, lizards, birds and mammals. The animals have the following general characters---

1-Form, Size and Symmetry. Form and size are almost constant in animals. Animal body is mostly symmetrical because of its regular form.

2-Movement and Locomotion. Animals can often move their parts rapidly because they have muscles. 

3-Growth. Growth in animals takes place proportionately in all parts of the body. It is limited and stops after the size is fixed for the species is reached.

4-Reproduction. Most animals reproduce sexually but they do not depend on external agencies for this. Asexual reproduction and regeneration are confined to lower forms.


Shortcomings of Two-Kingdom System

1-There wasn't any distinction b/w eukaryotes and prokaryotes.

2-Unicellular plants and animals are closely related but still they were placed in different kingdoms.

3-There are some organisms that do not exhibit any characteristic of any kingdom.