plant anatomy and reproduction Flashcards
processes of sexual reproduction in flowering plants
pollination + fertilisation (fusion of male and female gametes)
(f) sepals
enclose and protects the flower bud
(f) petals
often colourful and fragrant, serves to attract insects and other pollinators to the flower
(f) stamen
consists of a stalk (filament) tupped by an anther
(f) anther
sacs where meiosis occurs and pollen grains develop. pollen grains house the cells that develop into sperm (anther, filament)
(f) carpel
consists of a long slender neck (style) with a sticky stigma at its tip, at the base of the carpel is the ovary (sigma, style, ovary)
(f) ovary
produces reproductive structures called ovules, each containing one developing egg and the cells that support it
reproductive structures
stamen, anther, carpel, ovary
(d) pollination
transfer of pollen grains from an anther to stigma
describe the growth of the pollen tube and its entry into the ovule followed by fertilisation
pollen grain on the stigma germinate in response to the sugary fluid produced by the mature stigma, a pollen tube grows out from the pollen grain and the male gamete forms in thee tube. as the pollen tube grws, it secretes enzymes to digest the tissue of the stigma and style. the pollen tube grows down the style. the pollent tube enters the ovule through an opening in the ovule wall called the micropyle. within the ovule, the tip of the pollen tube absorbs sap and bursts, releasing the two male gametes. the nucleus of one of the male gametes fuses with the nucleus of the ovum to form the zygote. this is fertilisation.
types of pollination
self pollination, cross pollination
(d) self-pollination
transfer of pollen grains from the anther to the stigma of the same flower or of a different flower on the same plant
(d) cross-pollination
the transfer of pollen grains from one plants to the stigma of another plant of the same species
petals (wind vs animal)
(wind) : small/without petals, dull coloured
(insect) : large, brightly-coloured
nectar (wind vs animal)
(wind) : absent
(insect) : present
scent (wind vs animal)
(wind) : flowers are odourless
(insect) : flowers are fragrant
stigma (wind vs animal)
(wind) : large, feathery and usually protrude out of the flower to provide large surface area to trap pollen
(insect) : small, compact and do not protrude out the flower
stamen (wind vs animal)
(wind) : long pendulous filaments and protruding anthers. pollen grains easily shaken out from the anthers
(insect) : not pendulous, usually do not protrude out the flower
pollen (wind vs animal)
(wind) : more abundant. have smooth surfaces and are tiny/light so that they are easily blown about by the wind
(insect) : fairly abundant. usually larger and have rough surfaces to cling onto the body of insect
nectar guide (wind vs animal)
(wind) : absent
(insect) : may be present on the petals to guide insects towards the nectar
