Introduction
Biological Classification chapter 2 has a significant role to secure a good score in the CBSE board exam . This chapter is based on the classification of the different living organisms present in nature. Biological Classification class 11 notes covers a detailed explanation of the every important aspects of the chapter in concise and clear manner. This blog includes all the characteristic features of various species classified by renowned scientists.
Definition of Biological Classification
Biological Classification is the scientific process of arranging the different kinds of living organisms in various groups and subgroups based on their characteristic features. This procedure helps to identify the similarities as well as dissimilarities of organisms. This system of grouping helps to recognise the relationship among different species.
Process of Classification
Biological Classification class 11 notes include a brief discussion on the system of classification. The several methods of classifying the organisms are as follows:
- The idea of classifying the different kinds of living organisms was coined by Aristotle. He divided the plants into groups of herbs, shrubs, and trees. He classified them on the basis of the presence of RBC in their blood.
- The concept of the two kingdom classification was given by Carolus Linnaeus. The kingdoms are: 1. Kingdom Plantae 2. Kingdom Animalia
- The Five Kingdom classification was proposed by R.H. Whittaker. They are as follows:
- Monera
- Protista
- Fungi
- Plantae
- Animalia
Five Kingdom Classification
Five Kingdom Classification by R.H. Whittaker has been discussed in Biological Classification chapter 2. They are as follows:
1. Kingdom Monera
- Bacterium is the main component of Monera.
- This kingdom includes the bacteria having prokaryotic cells which do not have a well-defined nucleus.
- The bacteria can have shapes like: Coccus(spherical), Bacillus(rod-shaped), Vibrio (comma-shaped), and Spirillum (spiral-shaped).
- This kind of bacteria is reproduced by spore formation, fission also by DNA transfer.
Mycoplasma:
- The cell wall can not be seen in this kind of bacteria. It is the smallest living cell in nature. They can survive in the absence of oxygen.
- Bacteria can be divided into two groups: Archaea and Eubacteria.
Archaea- This kind of bacteria can mainly be found in harsh environments like marshy, salty, and also in hot springs. They are halophiles, methanogens, and thermoacidophiles.
- Methanogens – they can be seen in the gut of ruminant animals and produce biogas.
- Thermoacidophiles- They grow in hot springs
- Halophiles- Those are salt-loving bacteria.
Eubacteria- This type of bacteria has a rigid cell with a movable flagellum. Those are called ‘True bacteria”. In this group, blue-green algae are included.
- Photosynthetic autotrophs: The bacteria are called photosynthetic autotrophs as they contain chlorophyll. Those are colonial, unicellular, and filamentous algae.
- Chemosynthetic autotrophs: They play a significant role in recycling nutrients. They get the energy to generate ATP by the oxidation of numerous inorganic substances like nitrites and ammonia.
- Heterotrophic autotrophs: They are decomposers and they are used for various purposes such as curd production, nitrogen fixing. They are pathogens that cause typhoid, cholera and other diseases.
2. Kingdom Protista
- The organisms of this group are unicellular and eukaryotic.
- The kind of organisms have a well-defined nucleus and membrane-bound cell organelles.
- They reproduce both asexually and sexually. Some have flagella and cilia.
- They form a link between animals, plants, and fungi.
-
Chrysophytes
- It includes the golden algae and diatoms.
- These can be found in both freshwater and salty water of the sea.
- They are photosynthetic.
- The presence of silica made the cell wall unbreakable.
- Most of them have a single cell and are flagellates.
-
Dinoflagellates
- They can be found in the marine environment.
- They are photosynthetic.
- They have different colours, such as red, brown, blue, or yellow, depending on the pigment present in cells.
- They can grow rapidly.
-
Euglenoids
- They are the link between animals and plants.
- They are mostly found in stagnant water.
- They act like both heterotrophic and autotrophic.
- Chloroplasts can be found in most of the Euglenoids, and they are capable of photosynthesis.
-
Slime Moulds
- They are saprophytic protists that obtain nutrients from the decaying twigs or leaves.
- They can form an aggregate called a plasmodium under pleasant conditions.
- In unfavorable conditions, they differentiate and form spores bearing fruiting bodies at the top of their plasmodium.
- They can survive for many years for their well-structured as well as resistant walls.
-
Protozoans
This group includes heterotrophs, unicellular eukaryotes that are parasites.
Those can be divided into four categories:
- Amoeboid- They have pseudopodia to catch prey. They can be seen in freshwater, moist soil and in salty water. Marine Amoeboids possess silica.
- Flagellated- The Presence of Flagella is the main characteristic of those. They cause different types of diseases like sleeping sickness.
- Ciliated- Thousands of cilia can be found on the body surface. Cilia help to move food into the gullet.
- Sporozoans- Infective pores formation is the main feature of them, like Plasmodium.
3. Kingdom Fungi
- They are heterotrophic and obtain nutrients by absorption
- The cell wall is made of fungal cellulose or chitin.
- They are cosmopolitan.
- Fragmentation and fission are the processes of vegetative reproduction.
- Asexual reproduction can happen by spores, such as conidia, zoospores, etc.
- The process of sexual reproduction happens through ascospores, oospores.
- They possess Eukaryotic cells.
Classification of Fungi
| Attributes | Phycomycetes | Ascomycetes | Basidiomycetes | Deuteromycetes |
| Structure of mycelium | Aseptate,coenocytic | Septate and branched | Septate and branched | Septate and branched |
| Habit and Habitat | Damp and moist areas | Parasite, decomposite and Saprophytic | Found in logs, soil | Parasite, decomposert and Saprophytic |
| Asexsual Reproduction | Zoospores | conidia | Vegetative reproduction | conidia |
| Sexual reproduction | Isogamous, Zygospores | Ascospores | Basidiospores formed in basidium | Sexual reproduction can not be seen |
| Example | Rhizopus | Penicilium | Agaricus | Trichoderma |
4. Kingdom Plantae
- The rigid and well-structured cell wall is made of cellulose
- Most of them are autotrophic and eukaryotic by nature.
- They reproduce through sexual and asexual processes.
- This kingdom involves Gymnosperms, Bryophytes and Pteridophytes.
5. Kingdom Animalia
- These kinds of organisms are multicellular, eukaryotic and heterotrophic.
- The cell wall is absent.
- They have locomotor organs.
Acellular Organisms: Viruses, Viroids, Lichens & Prions
Biological Classification chapter 2 includes the explanation of classification of several Acellular organisms can be classified. Their characteristics are as follows:
Viruses
- Dmitri Ivanovsky coined the name “virus” for the organism of Tobacco Mosaic Virus.
- These non-cellular organisms are difficult to classify as living or non-living.
- Virus refers to the venom of a poisonous fluid.
- They are obligate parasites that cause various diseases such as polio, common cold, chicken pox etc.
Viroids
- They are the infectious agents, the smallest in size.
- They are formed by nucleic acid and have no protein shell.
Lichens
- Lichens can be defined as the symbiosis between algae and fungi.
- The algae produce food by the process of photosynthesis as they are autotrophic.
- Fungal constituents provide safety.
Prions
- They are smaller than a virus and consist of folded proteins.
- They cause several neurodegenerative diseases, like bovine spongiform encephalopathy in cattle.
Dreaming of top scores in Biology? Learn Physics with Ease, one of the most trusted coaching centres for Class 7 to 12 in Dumdum, offers an innovative as well as effective learning technique to the aspirants of different entrance exams. We provide well structured, informative and updated notes for each of the topics of Physics, Chemistry and Biology. We are renowned for our team of experienced faculty who are alumni of NIT Rourkela, high-quality study materials, well-organized teaching methods, and personalized care. We help students build a strong foundation in science for academic excellence.
Conclusion
A proper understanding of Biological Classification chapter 2 is necessary to achieve a desired score in Biology paper of CBSE board exam. Notes of Biological Classification consists of the system of grouping of the plants and animals and their characteristic features. Here, several crucial details of the classification has been provided.
Follow us on
- LinkedIn: linkedin.com/company/learnphysicswithease
- Facebook: facebook.com/learnphysicswitheasekolkata
- Instagram: instagram.com/learnphysicswithease