Biological Classification and Algae Lecture Review

Flashcards covering the economic importance of algae, biological classification systems, and the characteristics of viruses, viroids, prions, fungi, and protists.

Photosynthesis in Algae

The chemical process represented by $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$, through which algae perform about $50\%$ of $CO_2$ fixation on Earth.

Algin

A hydrocolloid (water-holding substance) produced by brown algae.

Carrageen

A hydrocolloid (water-holding substance) produced by red algae.

Chlorella

A unicellular algae used to make Single Cell Protein (SCP) for space travellers; it is rich in proteins, vitamins, and minerals.

Agar

A commercial product obtained from Gelidium and Gracilaria used as a solidifying agent in culture media, ice-cream, and jellies.

Artificial System of Classification

A system associated with Linnaeus based on a few superficial characters, mainly using floral morphological characters like the number and arrangement of stamens and carpels.

Natural System of Classification

A system associated with Bentham & Hooker based on natural affinities among organisms, considering both morphological and anatomical characters.

Phylogenetic System

A classification approach associated with Engler & Prantl based on evolutionary relationships and common ancestry.

Numerical Taxonomy

A system developed by Sokal & Sneath where all observable characters are given equal importance using numerical codes and computer processing.

Cytotaxonomy

A classification method based on cytological characters of cells, including chromosome number, structure, and behaviour.

Chemotaxonomy

Classification based on the chemical constituents of plants, such as alkaloids, flavonoids, proteins, and DNA.

Kingdom Plantae

Eukaryotic, chlorophyll-containing organisms with cell walls mainly made of cellulose; includes Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms.

Insectivorous Plants

Partially heterotrophic plants such as Bladderwort and Venus flytrap.

Alternation of Generation

The plant life cycle phenomenon involving two distinct phases: the diploid ($2n$) sporophytic phase and the haploid ($n$) gametophytic phase.

Kingdom Animalia

Multicellular, eukaryotic heterotrophs that lack cell walls and store food reserves as glycogen or fat.

Dmitri Ivanowsky

Investigator who in $1892$ recognized the causal agent of tobacco mosaic disease as being smaller than bacteria due to its ability to pass through bacteria-proof filters.

Contagium vivum fluidum

A term meaning 'infectious living fluid' coined by M.W. Beijerinck in $1898$ to describe the extract of infected tobacco plants.

W.M. Stanley

Scientist who in $1935$ demonstrated that viruses could be crystallized and that the crystals consist largely of proteins.

Capsid

The protein coat of a virus, which is made of small protein subunits called capsomeres.

Bacteriophage

A virus that infects bacteria, typically structured with a head containing genetic material, a collar, a sheath, and tail fibres.

Viroids

Discovered by T.O. Diener in $1971$, these infectious agents are smaller than viruses, lack a protein coat, and cause Potato Spindle Tuber Disease (PSTD).

Prions

Proteinaceous infectious particles consisting of abnormally folded proteins that cause diseases like Creutzfeldt-Jakob Disease (CJD) and Bovine Spongiform Encephalopathy (BSE/Mad Cow Disease).

Phycomycetes

A fungal group with aseptate and coenocytic mycelium that reproduce asexually via zoospores (motile) or aplanospores (non-motile).

Coenocytic

A continuous hypha with many nuclei, characteristic of the mycelium in Phycomycetes.

Ascomycetes

Known as 'Sac Fungi,' they have septate mycelium and produce sexual ascospores endogenously inside an ascus.

Basidiomycetes

Known as 'Club Fungi,' they have septate mycelium with clamp connections and produce sexual basidiospores exogenously on a basidium.

Plasmogamy

The first major step of sexual reproduction in fungi involving the fusion of cytoplasm (protoplasm) resulting in a dikaryotic stage ($n + n$).

Karyogamy

The fusion of nuclei in fungal reproduction, moving from a dikaryotic ($n + n$) stage to a diploid zygote ($2n$).

Chrysophytes

A group in Kingdom Protista consisting of Diatoms and Golden algae (Desmids) characterized by silica-embedded, indestructible cell walls.

Diatomaceous Earth

Accumulated silica remains of diatom cell walls used in polishing and the filtration of oils and syrups.

Dinoflagellates

Mostly marine photosynthetic protists with stiff cellulose plates and two flagella (longitudinal and transverse); some like Gonyaulax cause red tides.

Euglenoids

Freshwater organisms that have a protein-rich pellicle instead of a cell wall and exhibit mixotrophic nutrition.

Slime Moulds

Saprophytic protists that form an aggregation called a multinucleate Plasmodium under favourable conditions.

Amoeboid Protozoans

Protozoans that move and capture prey using pseudopodia (false feet), such as Entamoeba histolytica.

Trypanosoma

A flagellated parasitic protozoan responsible for causing African sleeping sickness.

Plasmodium (Protozoan)

A sporozoan that causes malaria and has an infectious spore-like stage in its life cycle.

Isogamous

Sexual reproduction involving the fusion of two gametes that are similar in size.

Oogamous

Sexual reproduction involving a large, non-motile female gamete and a small, motile male gamete.