Plant Kingdom

Kingdom Plantae includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms. This chapter begins with the systems of classification: artificial systems such as that of Linnaeus based on a few characters like the androecium, natural systems such as that of Bentham and Hooker based on natural affinities, and phylogenetic systems based on evolutionary relationships. Modern approaches include numerical taxonomy, cytotaxonomy and chemotaxonomy. You will then study algae, simple aquatic thalloid plants, and the classes Chlorophyceae, Phaeophyceae and Rhodophyceae, with their pigments, stored food and examples. These include Chlamydomonas, Volvox, Spirogyra, Laminaria, Sargassum, Polysiphonia and Gracilaria. Bryophytes, the amphibians of the plant kingdom, include liverworts like Marchantia and mosses like Funaria and Sphagnum, and their dominant plant body is the haploid gametophyte. Pteridophytes, such as Selaginella, Equisetum, Dryopteris and Adiantum, are the first terrestrial plants with vascular tissues, and some are heterosporous. Gymnosperms, like Cycas, Pinus and Ginkgo, bear naked ovules and seeds. Angiosperms bear seeds enclosed in fruits and range from the tiny Wolffia to tall Eucalyptus trees. Uses such as agar, algin and peat are also covered.

Detailed Worksheet: Plant Kingdom Section A - Definitions (10 marks) 1. Distinguish between artificial and natural systems of classification. (2 marks) 2. What are isogamy, anisogamy and oogamy? Give one example of each. (2 marks) 3. Why are bryophytes called the amphibians of the plant kingdom? (2 marks) 4. What is heterospory? Name two heterosporous pteridophytes. (2 marks) 5. What are coralloid roots? In which plant are they found? (2 marks) Section B - Calculations and Applications (15 marks) 6. In a moss, the cells of the leafy gametophyte have 8 chromosomes. State the number of chromosomes in the spores, the protonema, the zygote and the cells of the capsule. Explain your answers. (3 marks) 7. In Pinus, the leaf cells have 24 chromosomes. State the number of chromosomes in the pollen grain, the female gametophyte (endosperm), and the embryo. Explain why the endosperm of gymnosperms differs from that of angiosperms. (3 marks) 8. Algae carry out about half of the total carbon dioxide fixation on earth. If the total global photosynthetic fixation is 100 billion tonnes of carbon per year, calculate the amount fixed by algae. Give two other uses of algae. (3 marks) 9. Tabulate in words the main pigments and stored food of the three classes of algae. Identify the class of: Spirogyra, Fucus, Porphyra. (3 marks) 10. A Volvox colony has 2,000 cells. If each cell has 2 flagella, calculate the total number of flagella. If a Chlamydomonas cell divides to form 8 zoospores, how many divisions occur? (3 marks) Section C - Diagrams (10 marks) 11. Draw labelled diagrams of Chlamydomonas and Spirogyra. (4 marks) 12. Draw a labelled diagram of a moss plant (Funaria) showing the gametophyte and sporophyte. (3 marks) 13. Draw a labelled diagram of a fern (Dryopteris) showing its sori. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Compare bryophytes, pteridophytes and gymnosperms in terms of the dominant phase, vascular tissue, dependence on water and seed formation. (5 marks) 15. Explain the economic importance of algae, bryophytes and gymnosperms, with examples such as agar, carrageen, peat and Sequoia. (5 marks) 16. 'Heterospory is a precursor to the seed habit.' Explain this statement with reference to Selaginella and Salvinia. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams neatly with labels. Use correct scientific names.