Diversity In Living Organisms

Amongst different divisions of plants thallophyta is one division which has the simplest forms. It is the lowest group of plants. The body of members of thallophyta is generally thalloid.

Some members of thallophyta include ulothrix, spirogyra, cladophora, etc.

All the organisms are divided into five kingdoms which are Monera, Protista, Fungi, Plantae and Animilia. The bases for classifying all organisms into five groups are:

(i) Type of cellular organization: whether the organism is prokaryotic or eukaryotic

(ii) Body organization: whether the organism is multicellular or unicellular

(iii) Mode of obtaining food: whether the organism is autotrophic of heterotrophic

(iv) Presence or absence of cell wall

There are many differences between plants and animals but they are placed in different categories on the basis of one important character:

• Mode of nutrition: Plants are autotrophic whereas animals are heterotrophic.

The other differences are:

• Plant cells have a cell wall whereas animal cells don't.

• Plant cells have a big central vacuole whereas animal cells have one or more smaller vacuoles.

Fishes: The heart of fishes has two chambers, an auricle and a ventricle. The deoxygenated blood enters the auricle and is transported to ventricle from where it reaches the gills for the process of oxygenation. From here the blood is circulated in the body. This is an example of single circulation where the blood crosses the heart only once.

Frogs: Amphibians have a three chambered heart, two auricles and one ventricle. This means that the oxygenated and deoxygenated blood gets mixed up and causes an insufficient supply of oxygen to body cells.

The variety of plants, animals and other species on the Earth or in a particular habitat is known as biodiversity. Biodiversity is used to measure the health of a particular area, to check the condition of a particular species.

Classification of organisms is done to make their study simpler and easier. Organisms are classified on many bases like presence or absence of cell wall, their nature i.e. prokaryotic and eukaryotic, their habitat, etc.

Organisms are classified into 5 kingdoms, which are, Monera, Protista, Fungi, Plantae and Animalia.

**Additional Information:

Fungi and bacteria are not classified as plants. They exist in a different kingdom. But these do work on preparing food via the process of photosynthesis.

Both bryophytes and pteridophytes are small and delicate plants which reproduce by spore formation. Spore formation is optimum at lower temperatures. So, bryophytes and pteridophytes grow in moist and shady places.

Note: Bryophytes are also known as the amphibians of the plant kingdom as they need water to complete their life cycle.

Whales are not included in the class pieces (fishes) and considered a part of class Mammalia because of many reasons.

• The main characteristic of the member of class Mammalia is the presence of the mammary glands. Whales have mammary glands and other fishes do not, hence, whales are kept in class Mammalia.

• Whales are viviparous (give birth to young ones) as other mammals whereas pieces are oviparous (lay eggs).

• Whales possess lungs for respiration as other mammals whereas fishes have gills.

Local or vernacular names are not sufficient as there are different languages prevalent in different parts of the world and if we name any plant or animal according to the local language, no one from another part of the country, forget the world, would be able to understand it. So to solve this problem scientists came up with scientific naming in which all the plants and animals are named in the Latin language.

Differences between pteridophytes and phanerogames are as follows:

The differences between the members of aves and mammalia are as follows:

The differences between the members of amphibia and reptilia are as follows:

The differences between the members of porifera and coelentrata are as follows:

The differences between the members of Annelida and arthropods are:

The main criterion for classification of organisms as belonging to kingdom monera is 'type of cellular organization’, that is, whether the cell is prokaryotic or eukaryotic.

Prokaryotic cells do not have any double membrane bound structure, like the nucleus, chloroplasts, mitochondria, etc. The ribosomes present are 70s, different from that of eukaryotic cells.

Classification of organisms is done to make their study simpler and easier. Organisms are classified on many bases like presence or absence of cell wall, their nature i.e. prokaryotic and eukaryotic, their habitat, etc.

The major characteristics considered for classifying all organisms are:

● Type of cellular organization: whether the organism is prokaryotic or eukaryotic

● Body organization: whether the organism is multicellular or unicellular

● Mode of obtaining food: whether the organism is autotrophic of heterotrophic

● Presence or absence of cell wall

Before developing a hierarchy we need to finalise the elements which will define the basis for classification.

Based on these , the common characteristics are used for forming sub-groups.

For example, plants differ from animals in their body design, process of food formation i.e. photosynthesis, etc. But, the main classification between plants & animals is based on the property of locomotion because plants cannot move but animals can. Hence, locomotion is considered as the fundamental characteristic for distinguishing between plants and animals.

Some plants might have a thalloid body whereas some might have plant body differentiated into true roots, stem, and leaves. Some might have a naked seed whereas some might have seeds enclosed in a fruit. Therefore, Kingdom Plantae is divided into five major divisions which are Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms. They all are different from each other on a certain basis.

The bases of these divisions are:

(i) Presence or absence of distinct organs like whether the plant body is differentiated into true root, stem, and leaf or not.

(ii) Presence or absence of distinct and differentiated tissues, which can carry food (phloem) and water (xylem).

(iii) Presence or absence of seeds.

(iv) Whether the seeds are enclosed within fruits or not.

Binomial system of nomenclature, proposed by Carolus Linnaeus, is the most accepted system of scientific naming which is practiced currently. This type of naming consists of two words taken from the Latin origin, and if the word is not available in the Latin language then it is latinised.

There are four conventions which are followed while writing the scientific names. They are as follows:

(i) The first word out of the two words will be the genus whereas the second word would represent the species.

(ii) The name of the genus should start with the capital letter and the name of the genus should start with the small letter

(iii) The scientific name must be italicized, when printed

(iv) The scientific name must be separately underlined when it is hand written.

Example: It can be explained with the help of an example.

Panthera leo

• It is the common name of the lion.

• In this, the first word represents its genus - Panthera, while the second word represents the species - Leo.

• The scientific name has been italicized.

(A). Division Thallophyta

• The plant body is thalloid are not divided into true root, stem or leaves

• Conducting elements are absent in thallophytes

(B)Division Pteridophyta

• Pteridophyta are first true land plants

• They are seedless, vascular cryptogams

(C)Division gymnosperms

• They have naked seeds, that is, its seeds are not covered by fruit. Formation of the flower is absent.

• The seeds are pollinated by wind

(D)Phylum Coelenterata

• Presence of cnidoblast cells, therefore, phylum also known as cnidaria

• All the members of phylum Coelenterata are aquatic, mostly marine.

(E)phylum Annelida

• Body is metamerically segmented

• First Phylum having a true coelom

(F)phylum Arthropoda

• Animals having jointed appendages

• Largest and most successful phylum on the Earth

(G)subphylum protochordate

• Pharynx perforated by Gill slits.

• A post-anal tail is present. Brainbox is absent.

(H)subphylum Vertebrata

• The notochord is replaced by a cartilaginous or bony vertebral column in the adult

• Presence of dorsal hollow nerve cord

Protista is unicellular, eukaryotic organisms which have a heterotropic mode of nutrition. Some of the members of kingdom Protista are paramecium, euglena, etc.

The word taxonomy is obtained from a Greek word "taxis" which means arrangement. Therefore, taxonomy is the branch of biology that deals with the principles and practice of classification of plants and animals.

The phylum Porifera got its name from the word 'pores'. The body of all the members of Porifera is porous. The important characteristic of this phylum is the presence of different types of canal systems which help in nutrition, reproduction, and excretion.

Species can be described as a group of closely related organisms that are similar to each other and are usually capable of interbreeding and producing fertile offspring.

The open circulatory system is a type of circulatory system in which blood is pumped by the heart directly into the body cavities, where tissues are surrounded by the blood and not into blood vessels.

Example of animal groups having an open circulatory system are arthropods and mollusks.

Coelom is filled with blood in case of animal groups having an open circulatory system. The open circulatory system is a type of circulatory system in which blood is pumped by the heart directly into the body cavities, where tissues are surrounded by the blood and not into blood vessels.

Elephantiasis also known as Filariasis, is caused because of the filarial worm, Wuchereri bankrofti. Infection occurs when filarial parasites are transmitted to humans through mosquitoes. The disease causes swelling of the scrotum, legs, or breasts.

On the basis of the presence or absence of notochord Kingdom Animalia is divided into - non chordates and chordates. Vertebrata is included in chordates on the basis of the presence of a notochord, which in the adult stage is replaced by a Bony or cartilaginous vertebral column.

Kingdom Monera includes all the prokaryotes. Prokaryotes have a primitive nucleus, that is, without a nuclear membrane, 70s type or ribosomes, and no double membrane-bound organelle.

Example: Bacteria

Out of the given four, only Pteridophytes and gymnosperms have a well-defined tissue for conduction of water and food. The vascular tissue specialized for the conduction of water is known as xylem and the tissue specialized for the conduction of food is known as phloem.

Pisces and reptiles have scales which act as protection for their body. A scale is a rigid small plate on the body of fishes or reptiles that has many functions. The first is to protect them from enemies or predators. They also decrease water friction so that the animal can move easily in the water.

Though most of the fishes, amphibians, and reptiles are oviparous there are a few exceptions to this. There are a few fishes, amphibians and reptiles which are viviparous.

• Sharks, stingrays, eagle rays, and giant rays are viviparous fish.

• Few species of frogs, toads, and salamanders are viviparous.

• Skink, a type of lizard is also viviparous.

Tube feet are the small projections on the oral sources of the echinoderm which perform many functions.

The major function of the tube feet is movement. Other than movement, they also help in feeding and respiration.

Reefs are formed of colonies of coral polyps (a sessile form of members of phylum Cnidaria) held together by calcium carbonate. They are as hard as a rock.

The Great Barrier Reef is the world's largest coral reef system. The reef is located in the Coral Sea, off the coast of Queensland, Australia.

Gymno= naked; sperms= seed

This is the first division of kingdom Plantae which produces seeds. Gymnosperms don't produce flower and hence, the seeds produced are not enclosed in a fruit. The seeds produced are usually in the form of cones.

Out of the given four, the only dogfish is the real fish, all others belong to different phyla.

Jellyfish - common name of Aurelia (Coelenterata)

Starfish - common name of Asteria (Echinodermata)

Silverfish- a small insect in the order Zygentoma (Arthropoda)

Apart from Ctenophora, Echinodermata is one of the phyla which is exclusively marine. All the members of phylum Echinodermata are aquatic as well as marine.

RH Whittaker was the scientist who gave 5 Kingdom classification. He divided all the organisms into Monera, Protista, fungi, Plantae and animilia.

Blue-green algae (BGA) also known as cyanobacteria, is a member of kingdom Monera. Monerans are prokaryotic and lack a well-defined nucleus. They also lack double membrane-bound organelles. Ribosomes present in bacteria as of 70s type.

The book 'Origin of Species' was written by Charles Darwin, which was published on 24 November 1859. It gave evidence on evolution and suggested what had caused evolution to happen. The main concept of the book was the origin of species by means of natural selection.

Some fishes entirely different from others have a skeleton made up of cartilage and not bones. This helps the cartilaginous fishes such as sharks to reduce their weight and making it easier for them to swim at faster speeds with less energy being consumed.

Out of the above mentioned four, urchins are not the members of phylum Annelida; instead, they are the members of class Echinoidea, phylum Echinodermata. They are usually small, round and spiny in nature.

The book 'Systema Naturae' was written by Carolus Linnaeus in 1735. The book marked the beginning of zoological nomenclature.

The blood is in the coelom of animals having an open circulatory system. In such type of circulatory system, blood flows into a body cavity (coelom) and not in the blood vessels.

Fishes have two-chambered heart, the upper one is the auricle whereas the lower one is the ventricle. From the body the deoxygenated blood is carried to the auricle then from here it is transported to the ventricle and then to the gills for oxygenation.

Carolus Linnaeus introduced the Binomial Nomenclature system of scientific naming. According to the Binomial Nomenclature system, the scientific name of the organism consists of two words, the first one is the name of the genus where are the second one is the name of the species. The names are latinised. The scientific name is italicized when printed and separately underlined when handwritten.

Cyanobacteria and archaebacteria both belong to the Kingdom Monera and the members of Kingdom Monera are prokaryotes, that is, they have a primitive nucleus, no membrane bound organelles and ribosomes of 70s type.

There are a few bases for classification of organisms into five different kingdoms that are, monera, protista, fungi, Plantae and animilia.

(i) Type of cellular organization

(ii) Body organization

(iii) Mode of obtaining food

(iv) Presence or absence of cell wall

Jointed appendages are the characteristic feature of the members of Phylum Arthropoda. Arthro =jointed; poda=legs. All the members of Phylum Arthropoda have jointed appendages.

Coelentrata is the second phylum of kingdom animilia which do not contain any real organ. The body of the organism is diploblastic, acoelomate. All the members of phylum coelentrata are aquatic.

They have hard calcium carbonate structure which they use as skeleton. They have a spiny body.

Pteridophyta is the first land plants having true roots, stem and leaves but they lack flowers. The presence of flowers is the characteristic feature of division Angiospermae. Because of the presence of flowers, they are also known as phenerogames.

Spongilla is a type of freshwater sponge which has a water canal system. Numerous pores are also present in the body of the organism.

Out of the given organisms hydra, jellyfish and corals all belong to the phylum Coelentrata whereas filaria is a member of phylum nemathelminthes. Filarial worm are parasitic in nature.

Amphibians such as frogs, toads or salamanders have a three chambered heart (having two auricles and one ventricle), mucus glands which make the body slimy and gills or lungs present for respiration.

Scales are absent in amphibians.

● The hierarchy is as follows

● Kingdom

● Phylum

● Class

● Order

● Family

● Genus

● Species

So we can clearly see that the taxonomic hierarchy family comes between order and genus.

The body of the members belonging to division thallophyta is thalloid, that is, the members do not have differentiated body structures like root, stem or leaves.

The common names for the flat worms Fasciola hepatica and Taenia solium are liver fluke and tapeworm respectively.

The body of both the organisms is flat and the animals are parasitic in nature.

Pseudocoelom is the type of coelom present in the members of phylum Nemathelminthes/ Aschelminthes. In these organisms the coelom is present in the form of packets or pouches.

The characteristic feature of the animals belonging to Phylum arthropoda is the presence of jointed appendages. Arthro=jointed; poda=appendages

False

Cryptogames do not means plants having open reproductive organs whereas it is the division of kingdom plantae which contains plants having naked seeds.

False

Pteridophytes do not produce seeds. Production of seed is the feature of division gymnospermae and division angiospermae.

False

Thallophyta not called amphibians of the plant Kingdom whereas members of division Bryophyta are known as the amphibians of the plant Kingdom because they need water for reproduction.

True

Along with the embryo, stored food is also present in the seed which helps in the initial growth of embryo during germination of the seed.

False

Angiosperms do not bear naked seeds instead angiosperms bear covered seeds (seeds enclosed in flower and then in the fruit) whereas naked seed is the property of plants belonging to division gymnospermae.

True

Gymnosperms are the tall trees having well developed tissues for the conduction of water, minerals and food. Because of this ability they are usually perennial, evergreen and woody.

True

Cotyledons are a part of seed which represent a bit of pre-designed plant in the seed. On the basis of number of cotyledons present in the seed, the plant can be categorised as monocot or dicot.

True

Platyhelminthes or flatworms are usually parasitic in nature but they can also be free living.

Free living flatworm: turbellaria

Parasitic flatworm: liver fluke, tapeworm

True

The animals belonging to Phylum nematoda contains only the tissues and no real organs. The tissues behave as organs which perform different functions like excretion, respiration, nutrition, etc.

False

Most of the animals belonging to phylum mollusca have a muscular organ for movement which is known as 'foot'.

Presence of water driven tube feet for movement is the characteristic feature of animals belonging to phylum echinodermata.