Ch. 24- Reproduction of Seed Plants. Haploid Diploid. I. Reproduction With Cones and Flowers A. Alternation of Generations - All plants have a life cycle in which a diploid sporophyte generation alternates with a haploid gametophyte generation. MEIOSIS. Gametophyte Plant (N).
Gametophyte Plant (N)
Sporophyte Plant (2N)
2 ovules in which the female gametophytes
3. Pollination – The pollen is carried by the wind and caught on a sticky secretion (pollination drop) on one of the scales of the female cone.
a. Fertilization produces a zygote
which grows into an embryo
b. The embryo becomes enclosed in a seed
b. Second, the other sperm nucleus fuses with two polar nuclei in the embryo sac to form a triploid (3N) cell. This will grow into a food-rich tissue know as endosperm, which nourishes the seedling as it grows.
2. Dispersal by Wind and Water- Seeds dispersed by wind or water are typically lightweight, allowing them to be carried in the air or to float to the surface of the water.