Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Bryophytes are known as the 'amphibians of the plant kingdom' because they inhabit land but require for sexual reproduction.
The plant body is thallus-like, prostrate or erect, and lacks true roots, stems, or leaves; it is attached to the substratum by unicellular or multicellular rhizoids.
The dominant phase of the life cycle is the haploid () gametophyte, which produces gametes.
The male sex organ is the antheridium, producing biflagellate antherozoids, and the female sex organ is the archegonium, which is flask-shaped and produces a single egg.
The zygote () does not undergo reduction division immediately; it produces a multicellular sporophyte () that remains attached to and dependent on the gametophyte.
Sporocytes within the capsule undergo meiosis to produce haploid spores (), which germinate to form the gametophyte.
Liverworts (e.g., ) possess a thalloid body, while Mosses (e.g., ) have a gametophyte consisting of two stages: the and the stage.
📐Formulae
accounts for the life cycle.
💡Examples
Problem 1:
In a moss plant, if the chromosome number in the leaf cell is , what will be the chromosome number in the spores and the capsule cells?
Solution:
Spores: ; Capsule cells: .
Explanation:
The leaf of a moss is part of the gametophyte (), so . Spores are formed via meiosis but are haploid (), thus they have chromosomes. The capsule is part of the sporophyte (), so it contains chromosomes.
Problem 2:
How does reproduce asexually?
Solution:
Through fragmentation or specialized structures called gemmae.
Explanation:
Gemmae are green, multicellular, asexual buds that develop in small receptacles called gemma cups located on the thalli. They detach and germinate to form new individuals ().