Biological Classification - Salient features and classification of Monera, Protista and Fungi
Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Kingdom Monera: Comprises all prokaryotes. Cell walls are typically composed of peptidoglycan (polysaccharides and amino acids). They lack a defined nucleus and membrane-bound organelles. Genetic material is naked, circular .
Archaebacteria: Specialized bacteria inhabiting extreme environments. Methanogens are found in the gut of ruminants and produce (methane) from dung.
Eubacteria: Known as 'true bacteria'. Cyanobacteria (Blue-green algae) are photosynthetic autotrophs containing chlorophyll and often possess specialized cells called 'heterocysts' for fixation.
Mycoplasma: Smallest known living cells ( to ) that completely lack a cell wall and can survive without .
Kingdom Protista: Includes all unicellular eukaryotes. Boundaries are not well-defined. Includes Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds, and Protozoans.
Chrysophytes: Includes diatoms and golden algae (desmids). Diatoms have cell walls embedded with (silica), making them indestructible, leading to 'Diatomaceous earth' deposits.
Kingdom Fungi: Heterotrophic organisms. Cell walls are composed of chitin and polysaccharides. The body consists of long, slender thread-like structures called hyphae; a network of hyphae is called mycelium.
Fungi Classification: Divided into Phycomycetes (coenocytic mycelium), Ascomycetes (sac-fungi), Basidiomycetes (mushrooms/bracket fungi), and Deuteromycetes (imperfect fungi due to lack of known sexual stage).
Fungal Reproduction: Occurs vegetatively (fragmentation, fission, budding), asexually (conidia, sporangiospores, zoospores), and sexually (oospores, ascospores, basidiospores).
📐Formulae
(where is the final number of bacteria, is the initial number, and is the number of generations during binary fission)
(Methanogenesis process in Archaebacteria)
(Silica composition in the cell walls of Diatoms)
💡Examples
Problem 1:
A bacterial cell divides every minutes. How many bacteria will be formed from a single cell after hours?
Solution:
The number of bacteria is .
Explanation:
Given time = hours = minutes. Generation time = minutes. Number of generations . Using the formula , where : .
Problem 2:
Identify the organism that causes 'Red Tides' in oceans and explain the notation of its movement.
Solution:
(a Dinoflagellate).
Explanation:
These marine protists undergo rapid multiplication. They possess two flagella; one lies longitudinally and the other transversely in a furrow between the wall plates, providing a 'spinning' motion.
Problem 3:
Explain the ploidy levels during the sexual cycle of a typical Ascomycete fungus.
Solution:
Plasmogamy Karyogamy Meiosis.
Explanation:
In Ascomycetes, the fusion of protoplasms (Plasmogamy) is often followed by a dikaryotic phase () before the nuclei fuse (Karyogamy) to form a diploid () zygote. This zygote undergoes meiosis to produce haploid () spores.