NCERT Class XI: Biological Classification

Flashcards covering all topics from Chapter 2 of NCERT Biology Class XI

Theophrastus

Theophrastus

Known as the father of botany and ancient plant taxonamy & wrote Historia Plantarum which classified plants into herbs, shrubs, undershrubs, and trees.

Aristotle

earliest to attempt a more scientific basis for classification using simple morphological characters to classify plants into trees, shrubs and herbs, and dividing animals into two groups, those which had red blood and those that did not.

Anaima

Invertebrates with no red blood

Enaima

Vertebrates with red blood

Carolus Linnaeus

introduced the two-kingdom system; gave plant nomenclature in his “Species Plantarum” and plant classification in his “Genera Plantarum” using mainly characteristics of male plant reproductive organs.

Limitations of Two-Kingdom Classification.

this classification system grouped prokaryotes and eukaryotes together, didn’t account for cell wall composition, and unicellular and multicellular algae are placed in Kingdom Plantae due to the presence of a cell wall only.

Two-Kingdom Classification

classification system which grouped plants and animals into Kingdom Plantae and Animalia on the basis of cell wall only.

Haeckel

Introduced a t hree kingdom classification with Plantae, Animalia, and Protista

Copeland

Introduced four kingdom classification with Plantae, Animalia, Protista, and Monera.

Carl Woese

Introduced a six kingdom classification with two kingdoms for prokaryotic organisms.

Holophytic/Photosynthetic Nutrition

nutrition using photosynthesis

Ingestive/Holozoic Nutrition

nutrition through the consumption of nutrients by digestion

Absorptive/Osmotrophic Absorption

Nutrition through the release of enzymes that digest and break down nutrients from dead organic matter and absorb those nutrients

What did R.H. Whittaker’s five-kingdom classification introduce?

Whittaker’s system classified organisms into Monera, Protista, Fungi, Plantae, and Animalia, based on factors such as cell structure and nutrition .

Criteria for Five-Kingdom Classification

criteria include cell structure, thallus organization, mode of nutrition, reproduction, and phylogenetic relationship.

Absent in Five-Kingdom Classification

Viruses, viroids, prions, and lichens are not included in this classification system

Kingdom Monera

kingdom which contains prokaryotic unicellular organisms with a noncellulosic cell wall, absent nuclear membrane, and autotropic and heterotrophic nutrition.

Prokaryotic Cell wall

cellular structure made up of peptidoglycan(polysaccharides + amino acids) or murein

Periplasmic space

space between cell wall and cell membrane for the digestion of complex substances

Nucleoid

contain ds circular naked DNA + polyamines (non-histone proteins)

Eubacteria

Prokaryotic unicellular organisms divided into Gram-positive bacteria and Gram-negative bacteria and moves with the help of flagella.

Coccus (pl.cocci)

spherical bacteria, e.g. Streptococcus

Baciilus (pl. bacilli)

rod shaped bacteria, e.g E.coli

Vibrium (pl.vibrio)

comma-shaped bacteria, e.g Vibrio cholerae

Spirillum (pl.spirilla)

spiral shaped bacteria, e.g Spirillum

Flagella

cellular structure which allows for bacterial movement

Flagellation

Number and arrangement of flagella

Peritrichous

When flagella are found on the whole body of bacterium

Pili (sing.pilus)

hair like bacterial structures used for conjugation, and attatchment to environment/host.

F pilli or sex pilli

longer pili present only in donor (F⁺ or male) bacteria for help in conjugation

Fimbriae

short pilli used for attachment to rocks in streams and to the host tissue. These are found only in pathogenic bacteria.

Glycocalyx

protects the bacteria from W.B.C. and also helps in colony formation.

Capsule

thick, nonsticky, regular and smooth layer made of polysaccharides and polypeptides in the glycocalyx and increases the intensity of a disease

Slime layer

thin, sticky, loose, irregular, and rough layer made of polysaccharides in the glycocalyx

Gram + bacterial cell wall

thick and single layered bacterial cell wall mostly made up of peptidoglycan and some lipids.

Gram - bacterial cell wall

double layered cell wall with the inner layer being thin and composed of peptidoglycan while outer layer is thick and made up mostly of lipopolysaccharide and some lipoproteins and phospholipids

Mesosomes

special membranous structure formed by the extension or infoldings or invaginations of plasma membrane into the cell in the form of vesicles, tubules and lamellae and are functionally mitochondria like structures meaning that they contain oxidative enzymes.

Functions of the Mesosome

They help in cell respiration and cell wall secretion processes to increase surface area of the plasma membrane and enzymatic content. Help in DNA replication and distribution to daughter cells during cell division.

Glycogen granules

carb storage in bacteria

Volutin granules

phosphate reservoirs in bacteria

Plasmids

extra chromosomal/extranuclear/extra genomic genetic material that the ability to replicate independently and are of many types on the basis of their function or phenotypic character

F-plasmid (fertility factor)

plasmids which provide the ability to produce long pilli

F⁺ cells

male bacterial cells carrying the “F” plasmid and act as a donor

F^- cells

female bacterial cells lacking 'F' plasmid and act as recipient

Episome

when the “F” plasmid attaches with the main DNA

R-plasmid

plasmid which encodes enzymes and cell membrane proteins to fight antibiotics

Autotrophic bacteria

bacteria which use light or chemical energy for their own food synthesis.

Photosynthetic autotrophs/Photoautotrophs/Phototrophs

bacteria which use light energy for food synthesis, but do non-oxygenic photosynthesis because of the absence of water as the H-donor and oxygen not being the byproduct

e.g.- Rhodospirillum.

Bacteriochlorophyll 'a' & 'b'.

pigments in purple bacteria

Bacteriochlorophyll 'a', Chlorobium chlorophyll or Bacterioviridin.

pigments in green sulphur bacteria

Chemosynthetic autotrophs/Chemoautotrophs/Chemotrophs

non-photosynthetic autotrophic bacteria that use chemical energy instead of light energy for food synthesis through the oxidation of some chemical compounds and release of energy

Nitrifying bacteria

bacteria which oxidise nitrogenous compounds and obtain energy.

Nitrite bacteria

bacteria which convert ammonia into Nitrite (Nitrosomonas & Nitrococcus)

Nitrate bacteria

bacteria which convert nitrite into nitrates (Nitrobacter)

Heterotrophic bacteria

bacteria that receive their own food from dead organic matter or living organism.

Saprotrophic bacteria

bacteria which obtain food from dead and decaying organic matter.

e.g. Bacillus vulgaris, Clostridium botulinum, Pseudomonas

Parasitic bacteria

bacteria which obtain their food from living organism.

e.g. Mycobacterium leprae, Mycobacterium tuberculosis

Symbiotic bacteria

bacteria which form symbiotic relation with other organisms and convert atmospheric nitrogen into ammonia and then into nitrogenous ompounds like Amino acids, NO3 or salts of ammonia.

e.g. Rhizobium

Aerobic bacteria

bacteria that use oxygen in respiration.

E.g. Azotobacter

Anaerobic bacteria

bacteria that do not use oxygen for respiration, such as Clostridium

Binary Fission

Under favourable conditions, DNA replication takes place in bacterial cell and it divides into two cells due to formation of a septum (partition) in the centre of the cell and is a faster process then mitosis or meiosis.

Endosphore Reproduction

Under unfavourable conditions, bacterial cell forms only one endospore which is highly resistant to high temperature, radiations, antibiotics, and chemicals due to the presence of Ca-dipicolinate in wall.

Transformation

Transfer of genetic material from one bacterium to another bacterium through surrounding environment

Transduction

When the gene transfer process between two different bacteria is carried out by a virus (bacteriophage)

Archaebacteria

Domain of Monera which are the"Oldest living fossils", mostly anaerobic, and can survive in harsh habitats

Archaebacterial cell wall

bacterial cell wall made up of complex polysaccharides and complex polypetides.

Archaebacterial cell membrane

highly complex bacterial cell membrane composed of branched lipid chains

Methanogens

bacteria found in manshy area, feces, and in the rumen of cattle to produce methane (biogas).

E.g. Methanobacterium, Methanococcus, Methanomicrobium

Halophiles

bacteria found in extreme salty areas and contain bacteriorhodopsin in their cell membrane

E.g Halobacterium

Halophilic Bacteriorhodopsin

organelle found in bacterial cell membrane which absorbs suitable light radiations and produces ATP.

Thermoacidophiles

bacteria found at places where temperature is approx. 80°C to 100°C and medium is acidic, such as hot sulfur springs.

E.g Thermophilus, Sulfolobus

Cyanobacteria

First photosynthetic prokaryotic organisms that produced Oxygen on earth and found as symbionts with other organisms or free living

Chromatophores

membranous extensions into the cytoplasm in cyanobacteria

Chlorophyll a

green pigment

Carotenoids

yellow pigment

C-Phycocyanin

blue pigment used by cyanobacteria

C-Phycoerythrin

red pigment used by cyanobacteria

Spirulina

unicellular edible B.G.A containing large amounts of protein and used as fodder

Colonial Cyanobacteria

cyanobacteria found in colonies. e.g. Anabaena, Microcystis

Filamentous Cyanobacteria

cyanobacteria with many cells arranged in a row to form a filamentous body. E.g, Oscillatoria, Nostoc

Trichome

filament of cyanobacteria

Mucilaginous membrane/gelatinous sheath

cyanobacterial envelope formed by mucopolysaccharides which prevent water loss and dehydration

Cyanophycean starch

reserve food materials similiar to glycogen found in α-granules in cyanobacteria

Heterocyst

special thick walled, non-green cells found in Nostoc and Anabaena for nitrogen fixation and does not perform photosynthesis

Nitrogen fixation

converting atmospheric nitrogen into ammonia and then nitrogenous compounds like amino acids, nitrates which increase the fertility of soil.

Anabaena

found in the leaves of Azolla and form a symbiotic relationship with Azolla

Aulosira

found in plenty of paddy fields and performs nitrogen fixation due to which the production of rice is increased.

Oscillatoria

cyanobacteria which fixes nitrogen in paddy fields

Benefits of Cyanobacteria

benefits include: fertility to soil by nitrogen fixation, a very good source of protein, used as green manure, secrete toxins, which inhibits the growth of mosquito larva in water

Cons of Cyanobacteria

Cons include: water bloom and damage water tanks

Mycoplasmas

smallest, unicellular prokaryotic organisms lacking a cell wall, flagellum, and mesosome; exhibit osmotrophic nutrition and are facultative anaerobic, and act as saprophytes or parasites. They are resistant to penicillin and sensitive to tetracyclin & chloramphenicol.

Mycoplasmic Plant Diseases

Diseases due to this bacteria include aster yellow disease of sunflowers, witch’s broom of potato & ground nuts, little leaf disease in eggplants, and bunchy top of papayas.

Mycloplasmic Animal Diseases

Diseases due to this organism include primary atypical pneumonia and bovine pleuropneumonia.

Actinomycetes

important bacteria used for making antibiotics due to the mycolic acid present in thier cell wall

Barophillic prokaryotes

Prokaryotes which grow and multiply in very deep marine ediments.

Tuberculosis

Caused by Mycobacterium tuberculosis

Leprosy

Caused by Mycobacterium leprae

Tetanus

Caused by Clostridium tetani

Typhoid

Caused by Salmonella typhi

Cholera

Caused by Vibrio cholerae