Practical 6-bio.docx - Practical 6 Seed Plant(Gymnosperms...

This preview shows page 1 - 2 out of 5 pages.

Practical 6: Seed Plant (Gymnosperms and Angiosperms)OBJECTIVES:1.Describe the features of seed plant life cycle and the concept of the dominant generation.2.Describe the life histories and related reproductive structures of gymnosperms and angiosperms.3.Summarize the features that distinguish gymnosperms and angiosperms. 4.Discuss the advantages and disadvantages of seed plants to dominate land and their evolutionary adaptions on land.Experiment 1: AngiospermINTRODUCTION:Gymnosperms (720 species in 65 genera) are ancient seed plants that include ginkgos (Division Ginkgophyta), cycads (Division Cycadophyta), conifers (Division Conigerophyta), and gnetophytes (Division Gnetophyta). The term gymnosperm derivesfrom the Greek wood roots gymnos, meaning “naked” and sperma meaning “seed”. They are naked-seeded plants meaning that the ovule, which becomes a seed, is exposed on the sporophyte at pollination. Mature seed are enclosed in a fruit as are those of flowering plants. Gymnosperms are best known for their characteristics cones, called strobili. These strobili display sporangia and their subsequently developing ovulesand pollens. Gymnosperms do not require water for sperm to swim to reach the egg as do seedless plants. Instead, immense amount of windblown pollen are produced. Most gymnosperm cones, including the familiar pine cone, are complex whorls ofleaflike, woody scales around a central axis. The smallest cones includes those of the junipers (Juniperus) which have flesh scales fused into a structure resembling a berry. The larger cones may weigh 45kg and are produced by cycads. In most gymnosperm species, the female megastrobilus is larger and distinctive from the male microstrobilus.

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture