Definition
Binary fission (e.g. bacteria): one cell splits into two identical cells.
Budding (e.g. yeast): a small outgrowth (bud) forms and separates into a new individual.
Spore formation (fungi, bacteria in harsh conditions): tough spores can survive conditions the parent organism couldn't, and grow into new individuals once conditions improve — an adaptation for survival.
Rule
Vegetative propagation grows a whole new plant from a vegetative part (not seeds): runners (a horizontal above-ground stem rooting at nodes, e.g. strawberry), tubers (an underground stem storing food, e.g. potato).
Remember
Asexual reproduction is fast and needs no partner, but produces genetically identical offspring — sexual reproduction is slower but mixes genes from two parents, giving offspring more genetic diversity to cope with a changing environment.
Definition
A flower has four whorls: calyx (sepals, protect the bud), corolla (petals, often attract pollinators), androecium (stamens — the male part, produces pollen), gynoecium/carpel (the female part: stigma, style, ovary containing ovules).
Definition
Male gametophyte: the pollen grain. Female gametophyte: the embryo sac, formed inside the ovule.
The pollen tube grows from a germinated pollen grain down through the style, carrying male gametes to the ovule for fertilization.
Double fertilization (unique to flowering plants): one male gamete fertilizes the egg cell (forming the diploid, , embryo); another fuses with the two polar nuclei (forming the triploid, , endosperm — the seed's food store).
Remember
Sporophyte (the familiar plant body, ) and gametophyte (, produces gametes) alternate across generations — flowering plants' gametophyte stage is reduced to just the pollen grain and embryo sac, tucked inside the sporophyte.
Quick Recap
- ●Asexual: binary fission, budding, spore formation — fast, no partner, identical offspring
- ●Vegetative propagation: runners, tubers, etc. — grows a new plant from a vegetative part
- ●Flower's four whorls: calyx, corolla, androecium (male), gynoecium (female)
- ●Male gametophyte = pollen grain; female gametophyte = embryo sac
- ●Double fertilization: egg+sperm embryo; polar nuclei+sperm endosperm
