Key Vocabulary from Introduction to Protists, Viruses, Cryptogams & Spermatophytes

PROTISTS

• Eukaryotic, mostly unicellular or simple colonial organisms; lack true tissues.
• Exhibit every nutritional mode (autotrophy, heterotrophy, mixotrophy).
• Nine diagnostic criteria used in modern classification: presence/absence & type of cilia/flagella, pigments, mitosis types, mitochondrial cristae, ribosomal genetics, body plan, shell, nutrition, motility.

Seven Major Protist Groups (Raven & Johnson)

• Group 1 – Sarcodina (Rhizopoda, Foraminifera, Actinopoda)
• Group 2 – Multicellular Algae (Rhodophyta, Phaeophyta, Chlorophyta)
• Group 3 – Diatoms (Chrysophyta)
• Group 4 – Flagellates (Pyrrhophyta, Euglenophyta, Zoomastigophora)
• Group 5 – Sporozoans (Apicomplexa)
• Group 6 – Ciliates (Ciliophora)
• Group 7 – Slime & Water moulds (Acrasiomycota, Myxomycota, Oomycota)

PROTOZOA

• Microscopic (≈ 5–25 µm; some up to 2 mm).
• Habitats: fresh/salt water, moist soils, decaying matter.
• Survive desiccation via cysts.
• Free-living vs symbiotic vs parasitic forms.

Ecology Factors

1. Moisture – trophic stage always moist.
2. Temperature – optimum 16–25^\circ\text C; extremes <0 – 40^\circ\text C.
3. Light – affects phototrophs vs light-avoiders.
4. Nutrients (bacteria supply for holozoic forms).
5. pH – optimal 6.0–8.0.

Symbiosis Variants

• Commensalism (ecto/endocommensal).
• Mutualism (e.g., termite gut flagellates).
• Parasitism & hyperparasitism.

Cell Structure

• Pellicle/Plasmalemma; ectoplasm/endoplasm.
• Organelles: nucleus (macro & micronucleus in ciliates), mitochondria, ER, Golgi, food/contractile vacuoles.
• Locomotion: pseudopodia, flagella, cilia.

Reproduction

• Asexual – binary fission, multiple fission, budding.
• Sexual – syngamy, conjugation (ciliates), isogamy/anisogamy.
• Regeneration capacity dependent on nuclear material.

Classification (Sarcomastigophora et al.)

• Subphyla Mastigophora, Opalinata, Sarcodina.
• Additional phyla: Labyrinthomorpha, Apicomplexa, Microspora, Acetospora, Myxozoa, Ciliophora.

Economic Importance

• Links aquatic food chains (phyto→zoo flagellates→carnivores).
• Waste-water treatment, industrial nitrate/phosphate removal.
• Sewage degradation (anaerobic + aerobic stages).
• Fertilizer, single-cell protein.
• Human/animal diseases (amoebiasis, malaria, trypanosomiasis).

VIRUSES

• Acellular nucleic-acid strands enclosed in protein capsid; DNA or RNA never both.
• Sub-microscopic, filterable, no metabolism outside host.

Virus Structure

• Nucleoid + protein capsid (capsomeres) ± envelope (lipoviruses) ± core proteins.
• Capsid roles: protection, host entry, replication assistance, antigenicity.

Classification (Lwoff & Tournier 1966)

• Based on nucleic acid, capsid symmetry (helical/cubic/binal), envelope, helical diameter, capsomere number.
• Phylum Vira → Subphyla Deoxyvira (DNA) & Ribovira (RNA) → Classes (e.g., Deoxyhelica, Ribohelica…).

Bacteriophage Life Cycles

1. Lytic (T-series): adsorption → DNA injection → synthesis → assembly → lysis.
2. Lysogenic (λ-phage): prophage integration, replication with host genome, induction triggers lytic.

Human & Plant Viral Diseases (examples)

• HIV → AIDS.
• Influenza, Hep-B, measles, mumps, smallpox.
• Plant mosaics, yellows, curl, stunting.

BACTERIA

• Prokaryotic, unicellular, asexual (binary fission) ± parasexual.
• Sizes 1–5 µm (Dialister 0.3 µm; Bacillus butschlii 80 µm).

Morphology

• Cocci (micro-, diplo-, strepto-, tetra-, staphylo-, sarcinae).
• Bacilli (single/diplo/strepto).
• Spirilla; Vibrios.
• Flagellation types: mono-, lopho-, amphi-, peritrichous.

Cell Envelope

• Capsule/slime, peptidoglycan wall (half-rigid), plasma membrane.

Internal Structures

• Nucleoid (circular DNA), plasmids, ribosomes 70S, mesosomes, inclusions.

Reproduction & Spores

• Binary fission; endospore formation (Bacillus, Clostridium).
• Genetic exchange: conjugation (F-plasmid), transformation, transduction.

Nutrition & Metabolism

• Autotrophs (photo & chemo-). Heterotrophs – saprophytes, parasites, symbionts.
• Respiration: obligate aerobic/anaerobic, facultative anaerobes, thermophiles, psychrophiles.
• Fermentations → ethanol, lactic acid, methane.

Economic Roles

• Nitrogen fixation (Rhizobium), decomposition, sewage treatment, antibiotics (penicillin spoilage by penicillinase bacteria), vinegar, dairy, vitamins, enzymes.
  – Pathogens: plant (canker, wilt), animal (anthrax), human (TB, cholera, food poisoning).

FUNGI

• Eukaryotic, achlorophyllous, heterotrophic absorbers with chitin walls.

Thallus & Hyphae

• Mycelium of septate/non-septate hyphae; pseudoparenchyma/prosenchyma tissues.

Nutrition

• Saprophytic, parasitic, mutualistic (lichens, mycorrhizae).

Reproduction

• Asexual – fragmentation, budding (yeasts), sporangiospores, conidia, chlamydospores.
• Sexual – gametangial & gametic copulation, somatogamy, spermatization; plasmogamy + karyogamy + meiosis.

Major Divisions & Classes

1. Gymnomycota (slime moulds)
2. Mastigomycota (water moulds, chytrids, oomycetes)
3. Amastigomycota (Zygomycetes – Mucor, Rhizopus; Ascomycetes – Penicillium, Aspergillus; Basidiomycetes – Agaricus; Deuteromycetes – imperfect fungi).

Representative Life-cycles

• Rhizopus – asexual sporangiospores; sexual zygospore via conjugation.
• Aspergillus/Penicillium – conidia; ascocarps (cleistothecia).
• Agaricus – basidiocarp, clamp connections, basidiospores.

Economic Importance

• Decomposers, food (mushrooms), fermentation (bread, alcohol), antibiotics (penicillin, griseofulvin), enzymes, organic acids, dairy ripening.
  – Spoilage, toxins (aflatoxins), diseases (ringworm, rusts, smuts).

LICHENS & MYCORRHIZAE

• Lichen = symbiosis of fungus (mycobiont – usually Ascomycete) + alga/cyanobacterium (phycobiont).
  Types: crustose, foliose, fruticose.
  Reproduction: soredia, isidia; fungal sexual stage (ascocarps).
  Uses: pioneer colonizers, dyes (orchil), litmus, food (reindeer moss), bio-indicators.

• Mycorrhizae: obligate symbiosis of fungal hyphae with roots.
  Types: Endomycorrhizae (V-A mycorrhiza – Glomeromycetes) & Ectomycorrhizae (Basidiomycetes with pines, oaks). Enhance P uptake, water, disease resistance.

BRYOPHYTES

• Non-vascular embryophytes: liverworts, hornworts, mosses.
• Dominant gametophyte (n); dependent sporophyte (2n: foot, seta, capsule).
• Require water for fertilization (biflagellate sperm).
• Reproduce via spores (homosporous).
  Examples: Riccia, Marchantia, Anthoceros, Funaria.

PTERIDOPHYTES

• First vascular plants (xylem & phloem); seed-less.
• Sporophyte dominant, independent; true roots, stems, micro-/megaphyll leaves.
• Sporangia on sporophylls → homosporous (fern, Lycopodium) or heterosporous (Selaginella, Marsilea).
• Gametophyte (prothallus) independent (exosporic) or endosporic.
  Classes: Psilotopsida, Lycopsida (club mosses), Sphenopsida (Equisetum), Pteropsida (ferns).

GYMNOSPERMS

• Naked-seed vascular plants; ovules exposed on megasporophylls.
  Orders: Cycadales, Gingkoales, Coniferales, Taxales, Gnetales.
  • Exhibit heterospory & seeds; pollen tube delivers sperm; archegonia present.
  • Sporophyte massive (trees), gametophytes microscopic, endosporic.
  • Economic: timber (pine), resin/turpentine, ornamental cycads.

ANGIOSPERMS

• Flowering plants; ovules enclosed in carpels; double fertilization (n+n o 2n zygote, n+n+n o 3n endosperm).
• Divided into Monocotyledonae (1 cotyledon, parallel veins, scattered vascular bundles) & Dicotyledonae (2 cotyledons, net veins, vascular ring).
• Floral organ whorls: calyx (sepals), corolla (petals), androecium (stamens), gynoecium (carpels).
• Life-cycle: sporophyte dominant; gametophytes reduced to pollen grain (3-cell) & embryo sac (8-nucleate).

Specialized Tissues

1. Meristem (apical, cambium).
2. Ground tissue (parenchyma, collenchyma, sclerenchyma).
3. Epidermis (+cuticle, stomata, trichomes).
4. Vascular tissue – xylem (tracheids, vessels), phloem (sieve tubes, companion cells).

End of Comprehensive Notes