Question

Please give me full notes of diversity in living organisms chapter

Answer 1

*Biodiversity* :
The variety of living beings found in geographical area is called biodiversity of that area. Amazon rainforests is the largest biodiversity hotspot in the world.

*Basis of Classification:*
Ancient Greek thinker Aristotle classified living beings on the basis of their habitat. He classified them into two groups, i.e. those living in water and those living on land. But his classification was too simpleto justify inclusion of a particular organism into a particular group.

*Some examples of scientific bases of classification are as follows* :
Organization of nucleus:
Nucleus may or maynot be organized in an organism. On this basis, organisms can be divided into two groups, viz. prokaryotes and eukaryotes.
*(a) Prokaryotes:*
When nucleus is not organized, i.e. nuclear materials are not membrane bound; the organism is called prokaryote.

*(b) Eukaryotes:*
When nucleus is organized, i.e. nuclear materials are membrane bound; the organism is called eukaryote.

*Number of cells:*
An organism can be composed of a single cell or many cells. An organism with a single cell is called unicellular organism. On the other hand, an organism with more than one cell is called multicellular organism.

*Mode of Nutrition:*
On this basis, organisms can be divided into two broad groups, i.e. autotrophs and heterotrophs. An autotroph makes its own food, while a heterotroph depends on other organisms for food.

*Level of Organisation:*
Even in case of multicellular organisms, there can be different levels of organization. When a cell isresponsible for all the life processes, it is called cellular level or organization. When some cells group together to perform specificfunction, it is called tissue level of organization. When tissues group together to form some organs, it is called organ level of organization. Similarly organ system level of organization is seen in complex organisms.


*Five Kingdom Classification by Robert Whittaker (1959)*

*1. Monera:*
These are prokaryotes; which means nuclear materials are not membrane bound in them. They may or may not have cell wall. They can be autotrophic or heterotrophic. All organisms of this kingdom are unicellular. Examples: bacteria, blue green algae (cyanobacteria) and mycoplasma.

2. Protista:These are eukaryotes and unicellular. Some organisms use cilia or flagella for locomotion. They can be autotrophic or heterotrophic. Examples: unicellular algae, diatoms and protozoans.

*3. Fungi:*
These are heterotrohic and have cellwall. The cell wall is made of chitin. Most of the fungi are unicellular. Many of them have the capacity to become multicellular at certain stage in life. They feed on decaying organic materials. Such a mode of nutrition iscalled saprophytic. Some fungi live in symbiotic relationship with other organisms, while some are parasites as well. Examples: yeast, penicillum, aspergillus, mucor, etc.

*4. Plantae:*
These are multicellular and autotrophs. Presence of chlorophyll is a distinct characteristic of plants, because of which they are capable of doing photosynthesis. Cell wall is present.

*5. Animalia:*
These are multicellular and heterotophs. Cell wall is absent.


*Kingdom Plantae:*
The Plant Kingdom can be further classified into five divisions. Their key characteristics are given below:
*1. Thallophyta:*
The plant body is simple thallus type. The plant body is not differentiated into root, stem and leaves. They are commonly known as algae. Examples: Spirogyra, chara, volvox, ulothtrix, etc.
*2. Bryophyta:*
Plant body is differentiated into stem and leaf like structure. Vascularsystem is absent, which means there is no specialized tissue for transportation ofwater, minerals and food. Bryophytes are also known as the amphibians of the plant kingdom, because they need water to complete a part of their life cycle. Examples: Moss, marchantia.
*3. Pteridophyta:*
Plant body is differentiated into root, stem and leaf. Vascular system is present. They do not bear seeds and hence are called cryptogams. Plants of rest of the divisions bear seeds and hence are called phanerogams. Examples: Marsilear, ferns, horse tails, etc.
*4. Gymnosperms:*
They bear seeds. Seeds arenaked, i.e. are not covered. The word ‘gymnos’ means naked and ‘sperma’ means seed. They are perennial plants. Examples: Pine, cycas, deodar, etc.
*5. Angiosperms:*
The seeds are covered. The word ‘angios’ means covered. There is great diversity in species of angiosperm. Angiosperms are also known as flowering plants, because flower is a specialized organ meant for reproduction. Angiosperms are further divided into two groups, viz. monocotyledonous and dicotyledonous.
*(a) Monocotyledonous:*
There is single seed leaf in a seed. A seed leaf is a baby plant. Examples: wheat, rice, maize, etc.
*(b) Dicotyledonous:*
There are two cotyledonsin a seed. Examples: Mustard, gram, mango, etc.


*Kingdom Animalia:-*
The animal kingdom is classified into different phyla. Their detail is given below:
*1. Porifera:*
These animals have pores all overtheir body. The pores lead into the canal system. Water flows through the canal system and facilitates entry of food and exchange of other materials. The animal is not differentiated into tissues. The body is covered with a hard outer skeleton. These arecommonly known as sponges. They are marine animals. Examples: Sycon, spongilla, euplectelea, etc.
*2. Coelenterata:*
The body is made up of a coelom (cavity) with a single opening. The body wall is made up of two layers of cells (diploblastic). Some of the species live a solitary life while others live in colonies. Examples: Hydra, Jelly fish, Sea anemone, etc.
*3. Platyhelminthes:*
The body is flattened from top to bottom and hence the name platyhelminthes. These are commonly knownas flatworms. The body wall is composed of three layers of cells (triploblastic). Because of three layers, it is possible to form some organs as well. But a proper ceolom is absentin platyhelminthes and hence proper organs are absent. They are free-living or parasitic animals. Examples: Planaria, liver fluke, tapeworm, etc.
*4. Nematohelminthes:*
The body is bilaterally symmetric and there are three layers in the body wall. Animals are cylindrical in shape. A pseudocoelom is present and hence organs are absent. Examples: Roundworms, pinworms, filarial parasite (Wuchereria), etc.
*5. Annelida:*
True body cavity is present in these animals. The body is divided into segments and hence the name annelida. Each segment is lined one after another and contains a set of organs. Examples: Earthworm, leech, etc.
*6. Arthropoda:*
Animals have jointed appendages which gives the name arthropoda. Exoskeleton is present which is made of chitin. This is the largest group of animals; in terms of number of species. Circulatory system is open, which means blood flows in the coelomic cavity. Examples:cockroach, housefly, spider, prawn, scorpion, etc.
*7. Mollusca:*
The animal has soft body; which is enclosed in a hard shell. The shell is made of calcium carbonate. Circulatory system is open and kidney like organ is present for excretion. The body has well developed muscular feet for locomotion. Examples: Snail, mussels, octopus, etc.
*8. Echinodermata:*
The body is covered with spines, which gives the name echinodermata.Body is radially symmetrical. The animals have well developed water canal system, which is used for locomotion. Skeleton is made of calcium carbonate. Examples: Starfish, sea urchins, etc.
*9. Protochordata:*
Animals are bilaterally symmetrical, triploblastic and ceolomate. Notochord is present at least at some stages of life. Notochord is a long rod-like structure which runs along the back of the animal. Thisprovides attachment points for muscles. It also separates the nervous tissues from the gut. Examples: Balanoglossus, herdmania, amphioxus, etc.
*10. Chordata:*
Animals have notochord, pharyngeal gill slits and post anal tail; for at least some stages of life. Phylum chordata is divided into many sub-phyla; out of which we shall focus on vertebrata.