Practice question

Alternation of heteromorphic generations shows opposite polarity between major land plant lineages reflecting evolutionary transition. In bryophytes including liverworts, hornworts, and mosses haploid gametophyte forms persistent photosynthetic thallus or leafy shoot generating gametangia and dominating biomass; diploid sporophyte is unbranched, short-lived, nutritionally dependent via foot. In tracheophytes polarity reverses with dominant photosynthetic sporophyte. Angiosperms and gymnosperms display extreme reduction of gametophytes to few cells within sporophytic flowers and cones, pteridophytes show moderate independence but still sporophyte dominated. Bryophyte gametophyte dominance defines ecology.