1.
Alternation of generations : haploid (n) stage that produces gametes followed by diploid
(2n) stage producing spores.
2.
Haploid : gametes; half the number of chromosomes in somatic cell, indicated by n, result of meiosis.
3.
Diploid : somatic cells; double number of chromosomes in gametes, indicated by 2n; result of fertilisation.
1.
Gametophyte : generation producing gametes in gametangium/ gametangia sexual stage.
2.
Sporophyte : generation producing spores in sporangium/ sporangia – asexual stage.
NB: In higher plants the generations alternate in the life cycle of a plant; in lower plants reproduction is either through gametes
(sexual) or spores etc. (asexual).
1.
A haploid gametophyte generation that produces gametes (n) by mitosis ...
the gametes (n) fuse to form zygote (2n), the start of ...
2.
A diploid sporophyte generation that produces spores (n) by meiosis.
1.
2.
Mosses (Bryophyta)
Ferns (Pterophyta/ Pteridophyta)
Seed plants (Spermatophyta)
Gymnospermae (cone-bearing plants producing seeds)
Angiospermae (flowering plants producing seeds)
Exam guidelines require study of mosses and flowering plants to highlight alternation of generations.
Leaf-like structures of moss gametophyte
Sporangium of moss sporophyte
Fern leaf (sporophyte) with sori (groups of sporangia
GYMNOSPERMS
ANGIOSPERMS
Female cones at different ages Male cones
Mosses Ferns, gymnosperms and flowering plants
Gametophyte dominant
Sporophyte dominant