Biology Chapter on Protista

Kingdom Protista

• Protista includes Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds, and Protozoans.
• Members are primarily aquatic and serve as a link between plants, animals, and fungi.
• Eukaryotic cells have a defined nucleus and membrane-bound organelles; some possess flagella or cilia.
• Reproduction can be asexual or sexual, involving cell fusion and zygote formation.

Chrysophytes

• Comprises diatoms and golden algae (desmids), found in both freshwater and marine environments.
• Microscopic organisms that float in water currents (plankton) and are primarily photosynthetic.
• Diatom cell walls have silica, forming indestructible two-shell structures, resulting in deposits known as 'diatomaceous earth,' used in polishing and filtration.
• Diatoms are the chief producers in ocean ecosystems.

Dinoflagellates

• Mostly marine, photosynthetic organisms with pigments that create various colors (yellow, green, brown, blue, red).
• Possess stiff cellulose plates in their cell walls and two flagella (one longitudinal and the other transverse).
• Rapid multiplication of red dinoflagellates, like Gonyaulax, can cause 'red tides,' releasing toxins harmful to marine life.

Euglenoids

• Primarily freshwater organisms found in stagnant waters.
• Have a flexible protein-rich layer (pellicle) instead of a cell wall and possess two flagella.

Viruses

• Considered non-living acellular entities; composed primarily of proteins and genetic material (either RNA or DNA).
• Viruses infect host cells to replicate, often causing cell death.
• Dmitri Ivanowsky recognized viruses in 1892, calling them "venom" or "poisonous fluid."
• Bacterial viruses, known as bacteriophages, primarily consist of double-stranded DNA.
• Pathogenic viruses cause diseases such as mumps, smallpox, herpes, and influenza.

Kingdom Fungi

• Diverse kingdom of heterotrophic organisms; includes edible mushrooms and parasitic fungi (e.g., Puccinia, causing wheat rust).
• Bodies consist of hyphae (thread-like structures), forming a mycelium network; cell walls are made of chitin.
• Fungi can be saprophytic, parasitic, or symbiotic.
• Reproduction occurs vegetatively (fragmentation, fission, budding) and by spores (conidia, sporangiospores).
• The sexual cycle involves plasmogamy (fusion of protoplasm), karyogamy (fusion of nuclei), and meiosis.

Basidiomycetes

• Includes mushrooms, bracket fungi, and puffballs; the mycelium is branched and septate.
• Asexual reproduction is rare; vegetative reproduction occurs through fragmentation.
• Karyogamy and meiosis occur in specialized structures called basidia, producing basidiospores.

Deuteromycetes

• Known as imperfect fungi; sexual forms were only discovered later and classified accordingly.
• Reproduce solely by asexual spores (conidia) and play roles as saprophytes, parasites, or decomposers.

Kingdom Plantae

• Comprises eukaryotic, chlorophyll-containing organisms; includes algae, bryophytes, pteridophytes, gymnosperms, and angiosperms.
• Life cycle includes alternating sporophytic (diploid) and gametophytic (haploid) phases.
• Some plants are partially heterotrophic (e.g., insectivorous plants like Venus flytrap).

Kingdom Animalia

• Characterized by multicellular, heterotrophic organisms lacking cell walls; depend directly or indirectly on plants for nutrition.
• Nutritional process is holozoic (ingestion of food); store food reserves as glycogen or fat.
• Sexual reproduction involves male and female copulation, followed by embryological development.

Acellular Organisms

• Viruses, viroids, and prions are not categorized within the traditional kingdoms due to their acellular nature.
• Viruses lack cellular structure and are inert outside a living cell.

This quiz revolves around the kingdom Protista, covering various organisms such as Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds, and Protozoans. It emphasizes their aquatic nature and the eukaryotic structure of protistan cells. Test your knowledge on their classification, characteristics, and reproduction.