2. Biological Classification Flashcards
(38 cards)
Who was the first one to classify? How did he classify plants and animals into?
- Aristotle was first to classify.
- He classified on the basis of simple morphological characteristics (height)
3.Plants: Herbs, Shrubs, Trees - Animals: Red blood animals and non-red blood animals.
Who was the second one to classify? What are the groups he classified into? What was this classification called as?
- Carolus Linnaeus was the second one.
- He classified 2 kingdoms: Kingdom Plantae and Animalia with plants and animals resp.
- This type of classification was called as Two-kingdom classification.
What are the demerits of Two- Kingdom classification?
The demerits of two kingdom classification are:
1. Didn’t distinguish b/w eukaryotes & prokaryotes.
2. Didn’t distinguish b/w unicellular & multicellular.
3. Didn’t distinguish b/w photosynthetic (green algae) & non-photosynthetic (fungi).
4. Many organisms didn’t fall into either of the category.
Who proposed Five kingdom classification? Name the five kingdoms.
R.H.Whittaker proposed five kingdom classification.
The kingdoms are: Monera, Protista, Fungi, Plantae & Animalia.
What are the main criteria used for five kingdom classification?
The criteria:
1. Cell structure: Presence / Absence of cell wall, Prokaryotic/ eukaryotic
2. Body org.: Cell / tissue / organ / organ system & unicellular/ multicellular
3. Reproduction: Asexual/ Sexual
4. Mode of nutrition: Autotropic / Parasitic / Saprophytic
5. Evolutionary relationships: Ancestral History
What is three-domain system?
Three domain system has been proposed dividing Kingdom Monera into two domains and leaving other kingdoms in the third domain and thereby a six kingdom classification.
What are the merits of five kingdom classification?
Merits are:
1. Bacteria, blue green algae, fungi, mosses, ferns, gymnosperms & angiosperms under kingdom Plantae: due to presence of cell wall
2. Brought together prokaryotic bacteria and blue green algae (cyanobacteria) with other eukaryotic groups.
3. Grouped unicellular & multicellular organisms: Chlamydomonas & Spirogyra were placed under algae.
4. Did not differentiate b/w heterotrophic group - fungi and autotrophic green plants (fungi had chitin cell walls while green plants : cellulosic cell walls)
5. Thus, fungi placed in separate kingdom.
6. All prokaryotic org. were grouped under kingdom Monera and unicellular eukaryotic org. in kingdom Protista.
7. Chlamydomonas along with chlorella ( earlier placed in algae within plants and both have cell walls) with Paramoecium and Amoeba ( lack cell wall and earlier placed in animal kingdom) were brought together.
What are the characteristic features of Kingdom Monera? How are they grouped?
- Bacteria ; sole members
- Most abundant
- Live in extreme regions: hot springs, deserts, snow and deep oceans
- Most are parasitic
- Show most extensive metabolic diversity.
- They are grouped on the basis of shape:
a. Rod-like: basillus; Lactobacillus
b. Spherical: coccus; Streptococcus
c. Coma shaped: vibrio; Vibrio Cholerae
d. Spiral; spirillium; Spirochetae - Majority are heterotrophic.
- Reproduce mainly by fission.
- Under unfavourable conditions, they produce spores.
a. Formation of cyst
b. Metabolic activities slow down
c. Under favourable conditions, cyst breaks and duaghter
cells come out - Reproduce by sort of sexual reproduction by adopting a primitive type of DNA transfer from one bac. to another. (formation of clamp)
What are the two different categories of Kingdom Monera? Describe their features.
The two categories are:
1. Archaebac.: Primitive bac.
a. Live in harsh habitats
b. Motile flagella, rigid cell wall made up of highly resistant
peptidoglycon (responsible for survival in harsh
conditions)
c. Halophiles: extreme salty areas
Thermoacidophiles: hot springs
Methanogens: Marshy areas
i. In gut of ruminants (cows, buffaloes)
ii. Responsible for production of methane (biogas)
from dung of ruminants
- Eubac.: True bac.
a. Rigid cell wall and a motile flagellum (not mandatory)
b. Photosynthetic autotrophs: Cyanobac.
i. Blue green algae have chlor. a similar to green plants.
ii. Unicellular, colonial, filamentousn freshwater/marine
or terrestrial algae
iii. Colonies are surrounded by gelatinous sheath called
mucilagenous sheath.
iv. Often form blooms in polluted water bodies.
v. Some fix atmospheric nitrogen in specialised cells:
heterocysts in nostoc (filamentous blue-green algae) ,
anabaena
c. Chemosynthetic:
i. Oxidise various inorg. substances: nitrates, nitrites,
ammonia
ii. use released energy for ATP production
iii. Play a imp. role in recycling nutrients like nitrogen,
phosphorous, iron & sulphur
d. Heterotrophic:
i. Most abundant
ii. Functions:
ii.i. Imp. decomposers (majority)
ii.ii. Making curd from milk
ii.iii. Production of antibiotics
ii.iv. Fixing nitrogen in leguminous roots
ii.v. Pathogens causing damage (Cholera, typhoid,
tetanus, citrus canker)
What are the characteristics of mycoplasma?
- Completely lack cell wall
- Smallest living cells known
- Cant survive with oxygen
- Many are pathogenic in animals and plants.
- eg: PPLO - Pluera Pneumonia like org.
What are the main features of Kingdom Protista?
- Unicellular eukaryotes
- Forms a link b/w plants, animals and fungi.
- Primarily aquatic
- Well defined nucleus, membrane bound organelles
- No specific mode of nutrition.
- Reproduce asexually or sexually: cell fusion / zygote formation.
- Cellulosic cell wall if present.
What are the characteristics of Chrysophytes?
- Includes diatoms, golden algae (desmids)
- Found in fresh / marine environ.
- Microscopic and float passively in water currents (plankton)
- Mostly photosynthetic
- In diatoms: cell walls form two thin overlapping shells which fit together as soap box.
- Walls are embedded with silica, and thus indestructible.
- Diatoms have left large amounts of cell wall deposits in their habitat: diatomaceous earth (granular)
- This soil is being gritty and hence used in polishing, filtration of oils and syrups.
- Diatoms: “ chief producers” in oceans
What are the imp. characteristics of Dinoflagellates?
- Mostly marine and photosynthetic
- Many pigments present in their cells
- Cell wall made up of stiff cellulose plated on outer surface.
- Bi-flagellated: one longitudinally and other transversely in a furrow b/w wall plates
- Red dinoflagellates (Gonyaulax) undergo such rapid multiplication that they make the sea appear red - red tides.
- Toxins are released in large nos. that they might kill other marine animals.
Describe the unique features of euglenoids.
- Fresh water org. found in stagnant water.
- Instead of cell wall, they have protein rich layer called pellicle which adds flexibility to their body.
- Bi-flagellated: long and short one
- Photosynthetic in presence of light and predate over small org. in the absence of sunlight (heterotrophic)
- Pigments are identical to those of higher animals.
- Biologist puzzle
- eg: Euglena
What are the unique features of Slime Moulds?
- Saprophytic protists
- Body moves along decaying twigs and leaves engulfing org. material
- Under suitable conditions, they form an aggregation called plasmodium which may grow and spread.
- During unfavorable conditions: plasmodium differentiated and forms fruiting bodies bearing spores at tips.
- Spores possess true walls and are extremely resistant and survive for many years even under adverse conditions. They are dispersed by air currents.
- Resembles fungi
Describe the features of protozoans.
- Heterotrophs: predators or parasites
- Primitive relatives of animals.
- Four major groups:
a. Amoeboid:
i. Fresh water, sea water, moist soil.
ii. Locomotion and capture food by pseudopodia - false
feet
iii. Many have silica shells on their surface
iv. Parasitic forms: Entamoeba
b. Flagellated:
i. Free living / parasitic
ii. Have flagella (brittle)
iii. Parasitic forms cause diseases such as sleeping
sickness. (Trypanosoma)
c. Ciliated:
i. Aquatic
ii. Actively moving org. because of the presence of cilia.
iii. Have cavity (gullet) that opens to the outside of cell
surface
iv. Coordinated movement of rows of cilia causes water
laden with food to be steered into the gullet.
v. eg: Paramoecium: sexual dimorphism (micro and
macro nucleus)
d. Sporozoans:
i. Have infectious spore-like stage in their life cycle
ii. Most notorious plasmodium (malarial parasite) which
causes malaria.
What are the general features of Kingdom Fungi?
- Heterotrophic, cell wall: chitin and polysaccharides
- Common mushrooms and Toadstools: fungi
White spots on mustard leaves: parasitic leaves
Unicellular fungi, yeast: used to make bread & beer
Wheat rust causing Puccinia, Penicillium: used to make
antibiotics. - Cosmopolitan and occur in air, water, soil and on animals and plants.
- Grow in warm and humid places.
- Filamentous
- Bodies consist of long, slender thread-like structures called hyphae.
- Network of hyphae: mycelium
- Two types of hyphae:
i. Aseptate: Acellular - no partition in cells of hyphae and
continuous.
ii. Septate: Cellular - Partition in cells of hyphae.
iii. Coenocytic: some hyphae are continuous tubes filled
with multinucleated cytoplasm - Symbiotic relationships:
a. Lichens: fungi (gives water, mycobiont) + algae (gives
nutrition, phycobiont)
b. Mycorrhiza: (Roots of higher plant + Fungi) provides
phosphate to plants - Saprophytes: zbsorb soluble org. matter from dead
substrates
Explain the reproduction in fungi.
Vegetative means:
1. Fragmentation
2. Fusion
3. Budding
Asexual reproduction:
By spores called conidia/ sporangiospores/ zoospores
Sexual reproduction:
By oospores, ascospores, basidiospores
What are fruiting bodies?
Various spores in distinct structures are called fruiting bodies.
What are three events involved in sexual cycle of fungi?
- Fusion of protoplasms b/w two motile or non-motile gametes: plasmogamy
- Fusion of two nuclei: karyogamy –> leads to dikaryon stage
- Meiosis in zygote resulting in haploid spores
Briefly explain the process of sexual reproduction in fungi.
- Two haploid hyphae (n): which immediately results in diploid cells (2n)
- In basidiomycetes and ascomycetes: an intervening dikaryotic stage (n+n, i.e., two nuclei per cell) occurs; such a condition is called a dikaryon and the phase is called dikaryophase of fungus.
- Later, parental nuclei fuse and cells become diploid (zygote)
- The fungi form fruiting bodies in which reduction division (meiosis) occurs leading to formation of haploid spores.
What forms the basis for division of kingdom into various classes?
- Morphology of mycelium
- Mode of spore formation
- Fruiting bodies
Describe Phycomycetes.
- Aquatic habitat
- On decaying wood in moist and damp places or as obligate parasites on plants.
- Mycelium: aseptate and coenocytic & unbranched hyphae.
- Asexual reproduction: takes by zoospores (motile) or by aplanospores (non-motile). These spores are endogenously produced in sporangium.
- Sexual reproduction: A zygospore is formed by fusion of two gametes are similar in isogamous or dissimilar (anisogamous or oogamous)
- eg: Mucor, Rhizopus (bread mould) & Albugo - parasitic fungi on mustard
- Different from others in mode of reproduction
Describe Ascomycetes.
1.Sac fungi
2. Multicellular (Penicillium)
3. Unicellular (Yeast - Saccharomyces)
4. Saprophytic, decomposers, parasitic, coprophilous (growing on dung)
5. Mycelium branched, septate
6. Asexual spores: conidia produced exogenously on special mycelium called conidiophores. Conidia on germination produce mycelium.
7. Sexual spores: ascospores produced endogenously in sac like asci (singular ascus). Asci are arranged in diff. types of fruiting bodies called ascocarps.
8. eg: aspergillus, claviceps, neurospora.
9. Neurospora is used extensively in biochemical and genetic work.
10. Many members like morels and truffles are edible and are considered delicacies.
