Pollination

Pollination

• pollination: plant reproduction
• flower: the reproductive structure of an angiosperm; contain gametes (sperm + egg) needed for respiration
• gametophyte: gamete-producing
• male gametophyte: pollen grain (sperm)
• pollen grain forms two cells: generative cell (produces two sperm) + tube cell (makes a path for sperm to ovary)
• female gametophyte: embryo sac (egg)
• anther: produce pollen grains
• ovule: compartment inside ovary that contains embryo sac + egg
• stomata - opens so that oxygen and CO2 can enter/leave the plant; closes if too hot to prevent evaporation rate
• guard cells - open the stomata
• cuticle - protects the leaf (outer layer) from animals etc.
• palisade mesophyll layer - contains the chloroplasts so that the light can be stored
• spongy mesophyll layer - contains CO2 and this area does not need much light
• double pollination - 2 sperm fertilized at the same time
• first: fertilizes the egg (egg → embryo)
• second: fertilizes polar nuclei (PN → endosperm - food for embryo)
• cross pollination: transfer of pollen to a stigma of a different plant
• self pollination: transfer of pollen to the stigma of the same plant
• pigments: absorb all the sunlight
• → red + blue pigments absorbed the most, green the least (reflected)
• after fertilization, a seed forms around the embryo + the ovary ripens into a fruit