Sample Material of Our Online Coaching Programme
Subject: General Science
Topic: Plant Reproduction
INTRODUCTION
Animal life cycles have meiosis followed immediately by gametogenesis. Gametes are produced directly by meiosis. Male gametes are sperm. Female gametes are eggs or ova. The plant life cycle has mitosis occurring in spores, produced by meiosis, that germinate into the gametophyte hase. Gametophyte size ranges from three cells (in pollen) to several million (in a “lower plant” such as moss). Alternation of generations occurs in plants, where the sporophyte phase is succeeded by the gametophyte phase. The sporophyte phase produces spores by meiosis within a sporangium. The gametophyte phase produces gametes bymitosis within an antheridium (producing sperm) and or archegonia (producing eggs). Within the plant kingdom the dominance of phases varies. Nonvascular plants, the mosses and liverworts, have the gametophyte phase dominant. Vascular plants show a progression of increasing sporophyte dominance from the ferns and “fern allies” to angiosperms.