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Biological Classification Flashcards

1
Q

History of Biological Classification (8)

A
  1. Aristotle was the first to come up with a scientific basis of classification.
  2. He divided plants into trees, herbs and shrubs based on morphological characters.
  3. Divided animals into those which had red blood and those which did not.
  4. Linneaus’s time had a two kingdom system of classification- Plantae and Animalia.
  5. 2 kingdom was easy to use and understand but did not separate between uni/multicellular - eu/prokaryote - photosynthetic/non photosynthetic plants.
  6. Need for considering nature of wall, cell structure, mode of nutrition, mode of reproduction, habitat, phylogenetic relationships besides gross morphology.
  7. Whittaker’s system: Monera, Protista, Fungi, Plantae and Animilia
  8. Three domain system- divides Monera into two domains leaving eukaryotes in one domain- three domain - 6 kingdom.
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2
Q

Whittaker’s System of Classification and it’s Benefits (8)

A
  1. R H Whittaker in 1969 - 5 kingdom system - Monera , Protista, Fungi, Plantae and Animalia.
  2. Criteria for classification: 1) Cell Structure 2) Body Organization 3) Mode of Nutrition 4) Reproduction 5) Phylogenetic relationships.
  3. Monera - prokaryotes.
  4. Protista - unicellular eukaryotes.
  5. Fungi - chitin cell walls and heterotrophic - different kingdom from plants.
  6. Earlier plant kingdom - bacteria, blue green algae, fungi, mosses, ferns, gymnosperms and angiosperms - all had a cell wall.
  7. Multi and unicellular were placed together - Chlamydomonas and Spirogyra were both “plants”.
  8. Whittaker - Chlamydomonas and Chlorella (having cell walls) and Paramoecium and Amoeba (w/o cell walls) are placed together in Protista because criteria for classification has changed.
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3
Q

Kingdom Monera: Introduction (8)

A
  1. Only members are bacteria.
  2. Most abundant microorganisms.
  3. Varied habitats - snow, desert, hot spring, deep ocean.
  4. Many are parasites - live in or on other organisms
  5. Shapes - coccus: spherical, bacillus: rod, vibrio: comma, spirillum: spiral.
  6. Simple structure - complex behaviour.
  7. Most extensive metabolic diversity.
  8. Can be autotrophic (photo/chemo) OR heterotrophic (feed on living/ dead organisms)
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4
Q

Archaebacteria (6)

A
  1. Special - live in harsh habitats.
  2. Extremely salty areas - Halophiles.
  3. Hot springs - Thermoacidophiles.
  4. Marshy areas - Methanogens.
  5. Different cell wall structure - survive in extreme conditions.
  6. Methanogens - gut - ruminant animals - cows and buffalos- responsible for biogas production (methane) from their dung.
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5
Q

Eubacteria Autotrophic - Blue Green Algae and Chemosynthetic Bacteria (10)

A
  1. Eubacteria - true bacteria.
  2. Have rigid cell wall and sometimes motile flagellum.
  3. Cyanobacteria (blue green algae) have chlorophyll a similar to green plants and are photosynthetic autotrophs
  4. Can be unicellular, colonial, filamentous, freshwater, marine or terrestrial.
  5. Colonies surrounded by gelatinous sheath.
  6. Form blooms in polluted water bodies.
  7. Some can fix atmos. N2 - special cells - heterocysts - Nostoc & Anabaena.
  8. Chemosynthetic - oxidise inorganic substrates - nitrates, nitrites and NH3 - use released energy - ATP production.
  9. Chemo- help in recycling nutrients - P, S, N and Fe
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6
Q

Eubacteria Heterotrophic (4)

A
  1. Most abundant in nature.
  2. Important decomposers.
  3. Useful to humans - milk to curd, antibiotics and N fixation in leguminous plant roots.
  4. Harmful - pathogens - Cholera, Typhoid, Tetanus and Citrus Canker.
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7
Q

Reproduction in Bacteria (3)

A
  1. Mainly by fission.
  2. Unfavorable conditions - produce spores
  3. Sexual reproduction - primitive type of DNA transfer
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8
Q

Mycoplasma (4)

A
  1. Completely lack cell wall.
  2. Smallest known living cells.
  3. Can live w/o oxygen.
  4. Pathogenic in plants and animals.
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9
Q

Kingdom Protista: Introduction (7)

A
  1. Unicellular eukaryotes.
  2. Boundaries of the kingdom - not well defined.
  3. Includes - Chrysophytes, Dinoflagellates, Euglenoids, Slime Moulds and Protozoans
  4. Primarily aquatic.
  5. Link with fungi, plants and animals
  6. Well defined nucleus and membrane bound organelles.
  7. Reproduce asexually and sexually by cell fusion and zygote formation.
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10
Q

Chrysophytes (9)

A
  1. Diatoms and Desmids (golden algae)
  2. Fresh water and marine.
  3. Float passively with water currents - plankton.
  4. Most of them are photosynthetic.
  5. Diatoms - cell wall - two thin overlapping cells which fit over each other like a soap box.
  6. Cell wall embedded with silica - indestructible.
  7. Cell wall depositions - billions of years - diatomaceous earth.
  8. Gritty - polishing and filtration of oils and syrups.
  9. Diatoms - chief producers of the ocean.
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11
Q

Dinoflagellates (6)

A
  1. Mostly marine and photosynthetic.
  2. Appear yellow, green, brown, red or blue depending - pigment present.
  3. Cell wall - stiff cellulose plate - outer surface.
  4. Two flagella - 1) longitudnal 2) transverse - in a furrow between two wall plates.
  5. Red dinoflagellates - ex. Gonyaulax undergo massive multiplication - sea appears red - red tides.
  6. Toxins released - rapid multiplication - kill other marine animals - fishes.
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12
Q

Euglenoids (6)

A
  1. Found in fresh water - stagnant water.
  2. No cell wall - instead - protein rich layer - pellicle - makes their body flexible.
  3. Two flagella - one long and one short.
  4. Photosynthetic in the presence of sunlight - but in the absence of sunlight -behave like heterotrophs - predating on smaller organisms.
  5. Pigments identical - higher plants.
  6. ex. Euglena
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13
Q

Slime Moulds (7)

A
  1. Saprophytic protists.
  2. Bodies move along dead and decaying twigs and leaves engulfing organic material.
  3. Suitable conditions - aggregation - plasmodium - may grow and spread over several feet.
  4. Unsuitable conditions -plasmodium differentiates - fruiting bodies bearing spores at their tips.
  5. Spores have true walls.
  6. Spores - extremely resistant and can survive for many years even under adverse conditions.
  7. Spores - dispersed - air currents.
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14
Q

Protozoans Introduction (3)

A
  1. All heterotrophs - predators or parasites.
  2. Primitive relatives of animals.
  3. 4 major groups - 1) Amoeboid 2)Flagellated
    3) Ciliated 4)Sporozoans
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15
Q

Amoeboid Protozoans (4)

A
  1. Fresh water - sea water - moist soil.
  2. Amoeba - false feet - pseudopodia - capture prey.
  3. Many forms - silica shells on their surface.
  4. Some - parasites - Entamoeba
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16
Q

Flagellated Protozoans (3)

A
  1. Free living or parasitic
  2. Have flagella
  3. Parasitic - cause diseases - sleeping sickness - trypanosoma (trypanosoma gambiense / tryposomana brucei - vector - Tsetse fly
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17
Q

Ciliated Protozoans (5)

A
  1. Aquatic - actively moving
  2. Thousands of cilia
  3. Cavity - gullets - opens to the outside of the cell surface
  4. Coordinated movement of rows of cilia pushes water laden with food into the gullet.
  5. Ex: paramecium
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18
Q

Sporozoans (2)

A
  1. Have an infectious spore like stage in their life cycle.

2. Plasmodium causes malaria.

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19
Q

Fungi - what they are and where they’re found (from introduction paragraph of NCERT) (10)

A
  1. Heterotrophic.
  2. Great diversity in morphology and habitat.
  3. Seen on moist bread and rotten fruit.
  4. Mushrooms and toadstools.
  5. White spots on mustard - parasitic fungi
  6. Disease causing fungi - Wheat rust causing puccinia.
  7. Anti biotics - penicillium
  8. Yeast - beer and bread
  9. Cosmopolitan - present in air, water, soil, and on other plants and animals.
  10. Found in warm and humid places (food stored in refrigerator to prevent fungi and bacteria).
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20
Q

Body Organization of Fungi (from introduction paragraph of NCERT) (7)

A
  1. Yeast is unicellular - only exception.
  2. Fungi are filamentous.
  3. Bodies consist of long, slender thread like structures - hyphae.
  4. Network of hyphae - mycelium.
  5. Some hyphae are continuous tubes - multinucleate cytoplasm - coenocytic hyphae.
  6. Other hyphae might have septa or cross walls.
  7. Cell wall - chitin and polysaccharides.
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21
Q

Nutrition Of Fungi (from introduction paragraph of NCERT) (4)

A
  1. All heterotrophic.
  2. Saprophytic - absorb soluble organic material from dead substrates.
  3. Parasitic - depend on living plants and animals.
  4. Symbionts - algae - lichens and roots of higher plants - mycorrhiza.
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22
Q

Vegetative reproduction in Fungi (1)

A
  1. Fragmentation, fission and budding.
23
Q

Asexual reproduction in Fungi (1)

A
  1. Spores - conidia - sporangiospores or zoospores.
24
Q

Sexual reproduction in Fungi (8)

A
  1. Sexual reproduction - oospores, ascospores and basidiospores.
  2. Spores produced - distinct structures - fruiting bodies.
  3. Sexual cycle 1] Fusion of protoplasm between two motile or non motile gametes - plasmogamy.
    2] Fusion of two nuclei - karyogamy.
    3] Meiosis in zygote resulting in haploid spores.
  4. For sexual reproduction two haploid hyphae of compatible mating types come together and fuse.
  5. Some fungi - fusion of two haploid cells - immediately results in a diploid cell.
  6. But in ascomycetes and basidiomycetes - an intervening dikaryotic stage is seen where the cell has two nuclei ( n + n).
  7. This phase is called dikaryophase - later the parental nuclei fuse and cell becomes diploid.
  8. Fungi forms fruiting bodies - undergo reduction division to form spores.
25
Q

Basis for division of Fungi into classes (3)

A
  1. Morphology of the mycelium.
  2. Mode of spore formation.
  3. Fruiting bodies.
26
Q

Phycomycetes (9)

A
  1. Found in aquatic habitats.
  2. Also found on decaying wood or other damp and moist places.
  3. Also found as obligate parasites.
  4. Mycelium is aseptate and coenocytic.
  5. Asexual reproduction is by zoospores (motile) and aplanospores (non motile) -
  6. Spores are endogenously produced in the sporangium.
  7. Sexual reproduction - zygospore - produced by fusion of two gametes.
  8. Gametes can be isogamous or anisogamous or oogamous.
  9. Ex: Mucor, Rhizopus (bread mould) and Albugo (parasitic fungi causing white spots on mustard).
27
Q

Mycelium in Phycomycetes (1)

A

Aseptate and coenocytic

28
Q

Examples of Phycomycetes (3)

A
  1. Mucor
  2. Rhizopus (bread mould)
  3. Albugo (white spots on mustard- parasitic)
29
Q

Ascomycetes (10)

A
  1. Commonly called sac fungi.
  2. Mostly multicellular, rarely unicellular - unicellular ex: yeast (saccharomyces).
  3. Can be saprophytes, decomposers, parasites or coprophilous (growing on the dung).
  4. Mycelium is septate and branched.
  5. Asexual spores - conidia - produced exogenously from special mycelium - conidiophores.
  6. Conidia on germination produce mycelium.
  7. Sexual spores - ascospores arranged endogenously on sac like asci.
  8. Asci are arranged in different types of fruiting bodies called ascocarps.
  9. Ex: Penicillium, Aspergillus, Claviceps, Neurospora,
    Yeast (Saccharomyces), Morels and Truffles.
  10. Neurospora - extensively used in biochemical and genetic work. Morels and truffles - edible - delicacies.
30
Q

Mycelium in Ascomycetes (1)

A

Septate and branched.

31
Q

Examples of Ascomycetes (7)

A
  1. Aspergillus
  2. Claviceps
  3. Neurospora
  4. Penicillium
  5. Yeast (saccharomyces)
  6. Morels
  7. Truffles
32
Q

Basidiomycetes (10)

A
  1. Commonly known forms - mushrooms, puffballs and bracket fungi.
  2. Grow on soil, on logs or tree stumps and in living plants as parasites - smut and rust.
  3. Mycelium is septate and branched.
  4. Asexual reproduction is generally absent but vegetative reproduction by fragmentation is common.
  5. Sex organs are absent but plasmogamy is brought by fusion of two somatic / vegetative cells of different phenotype or strain.
  6. Dikaryotic structure - gives rise to basidium.
  7. Karyogamy and meiosis produce four basidiospores.
  8. Basidiospores - exogenously produced on basidium.
  9. Basidium arranged in fruiting bodies called basidiocarps.
  10. Ex: Agaricus (mushroom) , Ustilago (smut) and Puccinia (wheat rust).
33
Q

Mycelium of Basidiomycetes (1)

A
  1. Septate and branched.
34
Q

Examples of Basidiomycetes (3)

A
  1. Mushrooms - Agaricus, puff balls and bracket fungi.
  2. Smut - Ustilago.
  3. Rust - Puccinia (wheat rust).
35
Q

Deuteromycetes (7)

A
  1. Imperfect fungi - only asexual or vegetative phases are known.
  2. The asexual stage was discovered and put into deuteromycetes but when the sexual stage was discovered it would be moved to its correct class - ascomycetes or basidiomycetes.
  3. Asexual reproduction by spores - conidia.
  4. Mycelium is septate and branched.
  5. Some may be parasitic or saprophytic.
  6. Most of them are decomposers of litter and help in mineral cycling.
  7. Ex: Alternaria , Colletotrichum and Trichoderma
36
Q

Mycelium of Deuteromycetes (1)

A

Septate and branched.

37
Q

Examples of Deuteromycetes (3)

A
  1. Alternaria
  2. Colletotrichum
  3. Trichoderma
38
Q

Heterotrophic Plants (2)

A
  1. Insectivorous plants - Bladderwort and Venus Fly Trap.

2. Parasitic plants - Cuscuta

39
Q

Mode of Nutrition in Kingdom Animalia (3)

A
  1. Holozoic - by ingestion.
  2. Digest food in an internal cavity.
  3. Store the reserves as glycogen.
40
Q

Which organisms are missing in Whittaker’s system of Classification? (4)

A
  1. Lichens
  2. Viruses
  3. Viroids
  4. Prions
41
Q

What are Viruses? Why do they not find a place in classification? (3)

A
  1. They are not considered truly living.
  2. Viruses - non cellular organisms characterized by an inert crystalline structure outside the living cell.
  3. They infect a cell and take over its machinery to replicate themselves, killing the host.
42
Q

Dmitri Ivanowsky [1892] (3)

A
  1. Gave the name virus - meaning venom or poisonous fluid
  2. He gave the name to a microbe that he recognized were the cause of tobacco mosaic disease.
  3. He found that they were smaller than bacteria because they passed through bacteria proof filters.
43
Q

M. W. Beijerinek [1898] (2)

A
  1. Extract of the infected plants of tobacco could cause infection of healthy plants.
  2. Called the fluid as “contagium vividum fluidum”
44
Q

W. M. Stanley [1935] (4)

A
  1. Viruses could be crystallized.
  2. Crystals consist largely of proteins.
  3. Inert outside their specific hosts.
  4. Viruses - obligate parasites.
45
Q

Structure of Virus (5)

A
  1. Virus is a nucleoprotein where the genetic material is infectious.
  2. Protein coat - capsid - made of small units - capsomeres - protects the nucleic acids.
  3. Capsomeres arranged in helical or polyhedral geometric forms.
  4. Genetic material may be DNA or RNA.
  5. No virus contains both DNA and RNA.
46
Q

Genetic Material of Viruses that infect Plants (1)

A
  1. Single stranded RNA.
47
Q

Genetic Material of Viruses that infect Animals (1)

A
  1. Single or double stranded RNA or double stranded DNA.
48
Q

Genetic Material of Viruses that infect Bacteria (Bacteriophages) (1)

A
  1. Double stranded DNA.
49
Q

Diseases caused by viruses in animals (6)

A
  1. Mumps
  2. Small pox
  3. Rabies
  4. Influenza
  5. AIDS
  6. Herpes
50
Q

Diseases caused by viruses in plants (6)

A
  1. Mosaic formation (tobacco mosaic disease)
  2. Leaf curling
  3. Leaf rolling
  4. Yellowing
  5. Vein clearing
  6. Dwarfing
  7. Stunted growth
51
Q

Viroids (5)

A
  1. Discovered by T. O Diner.
  2. Smaller than viruses
  3. Caused potato spindle tuber disease
  4. Free RNA - no protein coat like viruses (therefore called viroid)
  5. RNA of low molecular weight
52
Q

Prions (4)

A
  1. Abnormally folded protein - transmitted infectious neurological diseases.
  2. Similar in size to viruses.
  3. Cause Bovine spongiform encephalopathy (BSE) - mad cow disease in cattle
  4. In humans - analogous variant of BSE - Cr Jacob disease
53
Q

Lichens (6)

A
  1. Symbiotic association between algae and fungi.
  2. Phycobiont - algae
  3. Mycobiont - fungi
  4. Algae prepare food
  5. Fungi provide shelter and absorb mineral nutrients and water
  6. Lichens are good pollution indicators.
54
Q

Structure of Bacteriophage

A
  1. Head - collar - sheath - tail fibers

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