NCERT Class XI: Biological Classification

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

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.

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

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

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.

Methanogens

bacteria found in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals

E.g. Methanobacterium, Methanococcus, Methanomicrobium

Halophiles

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

E.g Halobacterium

Thermoacidophiles

bacteria found at places such as hot sulfur springs.

E.g Thermophilus, Sulfolobus

Cyanobacteria

Photosynthetic unicellular autrotrophs that have chlorphyll a similiar to green plants and can be found as colonial or filamentous and as freswater/marine or terrestrial algae.

Chlorophyll a

green pigment

Spirulina

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

Colonial Cyanobacteria

cyanobacteria found in colonies surrounded by a gelatinous sheath and often form blooms in polluted water bodies.

e.g. Anabaena, Microcystis

Filamentous Cyanobacteria

cyanobacteria with many cells arranged in a row to form a filamentous body.

E.g, Oscillatoria, Nostoc

Cyanophycean starch

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

Heterocyst

specialized non-green cells that fix atmospheric nitrogen. Found in Nostoc and Anabaena.

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 that completely lack a cell wall and can survive without oxygen. Many are pathogenic in plants and animals.

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

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

Anthrax

Caused by Bacillus anthracis

Citrus canker

Caused by Xanthomonas citri

Crown gall in plants

Caused by Agrobacterium tumefaciens

Clostridium botulinum

causes botulism (lethal food poisioning)

Lactobacillus lactis

bacteria used in yogurt production and increases vitamin b12 in yogurt.

Streptomycin

antibiotic obtained from Streptomyces griseus (bacteria)

E.coli

bacteria known as pollution indicating bacteria in water

E.coli and Agrobacterium

bacteria used for genetic engineering

Kingdom Protista

kingdom which includes primarily aquatic single-celled eukaryotes that contain a well defined nucleus, membrane-bound organelles, and some have cillia or flagella. Can produce sexually or asexualy by cell fsion and zygote formation. Not clearly defined

Mixotrophic Nutrition

having more than one type of nutrition

Sexual reproduction in Protists

sexual reproduction in this kindgom occurs when haploid gametes fuse to form a syngamy and produces a diploid zygote which undergoes meiosis to from haploid progeny

Isogamous Sexual Reproduction

sexual reproduction where morphologically and physiologically similar gametes fuse

Anisogamous Sexual Reproduction

sexual reproduction where morphologically different gametes fuse

Oogamous Sexual Reproduction

developed form of anisogamous reproduction were a small, motile male gamete fuses with a large, non-motile female gamete to form a zygote