Diversity of Living World and Plant Kingdom
What the exam tests
This domain covers classification and the diversity of algae, bryophytes, pteridophytes, gymnosperms, and angiosperms. Questions ask you to place an organism in the correct group using a combination of habitat, vascular tissue, dominant generation, and reproductive structures, and to recall diagnostic pigments and examples.
Core rules and concepts
- Binomial nomenclature: genus capitalized, species lower case, both italicized when printed; the author abbreviation is not italicized.
- Hierarchy: Kingdom → Division → Class → Order → Family → Genus → Species.
- Algae are chlorophyll-bearing thallophytes. Chlorophyceae store starch; Phaeophyceae contain fucoxanthin; Rhodophyceae contain phycoerythrin.
- Bryophytes are amphibious plants with no true vascular tissue; the gametophyte is dominant and the sporophyte is dependent on it.
- Pteridophytes are the first true vascular plants; the sporophyte is dominant and the gametophyte is a small free-living prothallus.
- Gymnosperms have naked ovules and no ovary or fruit; angiosperms have flowers, enclosed ovules, double fertilization, and fruit.
- Alternation of generations: haplontic (many algae), diplontic (gymnosperms and angiosperms), haplodiplontic (bryophytes and pteridophytes).
Worked example
A plant has vascular tissue, a free-living gametophyte, and spores, but no seeds. Which group fits? Vascular tissue rules out bryophytes; no seeds rules out gymnosperms and angiosperms; a free-living gametophyte fits pteridophytes, such as a fern. The reasoning depends on the combination of traits, not on one feature alone.
Traps that cost marks
Do not call the moss sporophyte independent - it is attached to the gametophyte. Do not confuse naked seed with no seed. Brown algae are not identified by chlorophyll b; their accessory pigment is fucoxanthin. In angiosperms the sporophyte is dominant, but the gametophyte is still present and reduced.