Plant Reproduction Flashcards
What are flowering plants called?
angiosperms
What ploidy level are most flowering plants?
diploid
Where does meiosis take place in plants, what does it produce?
within the reproductive tissues
produces haploid spores which contain gametes
What is the male spore? produced where?
pollen grains, produced in the anther
What is the female spore? produced where?
embryo sac, produced in the ovule, in the ovary
What do many species of flowers contain? (reproductive organs) making them what?
hermaphroditic, the flowers contain both male and female parts
What is the general pattern seen in all flowers?
a flower is four sets of modified leaves arising from the receptacle at the base of the flower
What is the calyx?
the outermost ring of structures, which comprises the sepals.
They are usually green and protect the flower bud.
Where is the corolla located? what is it?
inside the sepals, a ring of petals
These range from abscent to small and pale green to large and brightly coloured
What is the stamen?
male parts of the flower, consists of a filament supporting an anther
What does the filament contain and do?
contains vascular tissue
transports sucrose, mineral ions, and water to the developing pollen grains
What does the anther contain? how many? what happens when mature?
4 pollen sacs arranged in 2 pairs
when mature the pollen sacs dehisce (open and release the pollen)
What structure is located in the centre of the flower?
the carpel, which are female parts of the flower
What structures does the carpel consist of?
stigma
style
ovary
What is the function of the stigma?
attract the pollen grains
What is the function of the style?
connects the stigma to the ovary, is where the pollen tube grows
What is the function of the ovary?
hold egg cells, contains ovules waiting to be fertilised by pollen
How do insect pollinated flowers distribute their pollen?
They attract pollinators like Bees, through colourful petals, scent, and nectar. As the bee enters the flower the anthers brush against it’s lorax and legs leaving sticky pollen behind
What happens when the bee carrying pollen enters another flower?
it brushes some of the pollen against the ripe stigma, cross-pollination has taken place
How do wind pollinated flowers distribute their pollen?
their anthers hang outside the flower so that the wind can blow away the small, smooth, and light pollen.
How do wind pollinated flowers adapt to receive pollen?
The feathery stigmas hang outside the flowers and provide a large surface area for catching pollen grains that are blown into their path.
What undergoes meiosis in the pollen sacs of the anther? forming? (development of the male gamete)
diploid pollen mother cells, each forms a tetrad congaing four haploid cells
What is the tapetum, what does it do?
a layer of cells around the pollen sac, provides nutrients and regulatory molecules to the developing pollen grains
has a significant role in the formation of the pollen cell wall
What properties does the cell wall of the pollen grains have?
is tough and resistant to chemicals
resists desiccation
UV light cannot penetrate pollen grains
What do pollen grains resisting desiccation allow?
so pollen grains can be transferred from one plant to another without drying out
What does UV light being unable to penetrate pollen grain cell wall do?
the DNA in pollen that is carried at high altitude is protected from mutation
What does the haploid nucleus in the pollen grain undergo? producing what?
mitosis, producing 2 nuclei (a generative nucleus and a tube nucleus
What is produced when the generative nucleus undergoes mitosis? (male gamete)
2 male nuclei
What happens when the pollen is mature?
outer layers of anthers dry out
What does the drying out of the anthers when pollen is mature cause?
tension in lateral grooves
until eventually dehiscence occurs in which tension pulls the walls of the anther apart and the edges of the pollen sacs curl away
What is the opening called that exposes the pollen grains during dehiscence, what then happens?
the stomium
exposes the pollen grains and they are carried away by insects or by wind
What is dehiscence?
the opening of the anther, releasing pollen grains
What happens in the ovule in development of the female gamete?
a megaspore mother cell undergoes meiosis making four haploid cells
How many of these 4 haploid cells disintegrate? (female gamete) (meiosis of megaspore mother cell)
3
What happens to the remaining haploid cell? (female gamete) (meiosis of megaspore mother cell)
Undergoes 3 rounds of mitosis, producing eight haploid nuclei, one of which is the female gamete, 2 fuse to form polar nucleus, 3 antipodals, 2 synergids
What can the female gamete also be called?
egg cell or oosphere
What happens to 2 of the haploid nuclei produced in mitosis of haploid cell? (female gamete)
they fuse to make a diploid nucleus called the polar nucleus
What is the nucellus?
a layer of cells which provides nutrients
What are integuments?
two layers of cells around nucellus
protective layer