Sexual Reproduction in the Flowering Plant Flashcards
which part of the plant is specialised for sexual reproduction
the flower
gamete
haploid cell, capable of fusion
when do gamete nuclei fuse and what is made
they fuse at fertilisation to form a diploid zygote
zygote becomes a
seed
seed becomes a
new plant
plants produced by sexual reproduction will show
genetic variation
gametes to zygote and endosperm
polination and fertilisation
zygote and endosperm to seed
mitosis
seed to plant 3
germination
dispersal
dormancy
bit that the flower sits on
sepal
what are all the parts of the flower attached to
the receptacle at the top of the flower shoot
sepals
green leaf-life structures which protect the flower while it is a bud
petals
brightly coloured with nectaries
function of petals
attract insects for pollination
male part
stamen
stamen
consists of filament (stalk) and anther
function of anther
produces pollen
female part
carpel
carpel
consists of the stigma, style and ovary with ovule
function of the stigma
receives pollen
function of the ovule
produces the egg
end result of sexual reproduction of a flower plant
a seed or seeds inside of a fruit
after fertilisation the ovule becomes
a seed
after fertilisation the ovary becomes
the fruit
what does an anther have?
4 pollen sacs
what occurs in the pollen sacs (first)
diploid microspore mother cells divide by meiosis to produce four halpoid microspores each
what happens to each microspore
each microspore divides by mitosis to form a pollen grain with 2 haploid nuclei
the 2 haploid nuclei in the pollen grain are called
the generative nucleus and tube nucleus
the mature pollen grain forms
a wall
what does each carpel have at its base
an ovary with 2 or more ovules
first thing that occurs in the ovule
the diploid megaspore mother cell divides by mitosis to form 4 haploid cells
what happens to the 4 haploid cells in the ovule
3 break down
4th haploid cell in the ovule that does not break down
enlarges to form the embryo sac
what happens to the embryo sac
it divides 3 times to form 8 nuclei
what happens to 3 of the 8 nuclei from the embryo sac
one nucleus becomes the egg cell (n) and 2 become the polar nuclei (n) these are the female gamete
describe the walls of a mature ovule
it has 2 walls called the integuments that enclose the embryo sac and there is a tiny opening in the integuments for the micropyle (for entry of pollen tube)
as the pollen grains mature, what happens to the anther
the wall of the anther shrinks and dies out
how are the pollen grains released when anther dies
a line of dehiscence (split) appears down each side of the anther, the walls split open and the pollen grains are released
what must happen so that fertilisation and seed production to occur
pollen grains must be transferred from the anther to the stigma
pollination
the transfer of pollen from anther to stigma
2 types of pollination
self pollination
cross pollination
self pollination
pollen grains are transferred onto the stigma of the same flower (or onto another flower of the same plant)
cross pollination
pollen grains are transferred onto the stigma of a flower on another plant of the same species
what does cross pollination do
increases genetic variation
which type of pollination is more common
cross pollination
how is cross pollination carried out
by insects or the wind
3 parts of insect pollinated flowers that show characteristics
flowers, pollen grains and stigmas
flowers of insect pollinated flowers
brightly coloured petals, sweet smelling and have nectaries to attract insects 1
pollen grains of insect pollinated flowers
spiked and sticky and they will stick well to the insects body
stigmas of insect pollinated flowers
flat and stick and inside the flower to ensue that the insect brushes against them
3 insect pollinated flowers
buttercup
daisy
wallflower
flowers of wind pollinated flowers
flowers are small, seals and petals are green or often absent to allow free circulation of air, no perfume or nectar
pollen of wind pollinated flowers
large quantity of pollen produced to increase chances of pollination
pollen grains of wind pollinated flowers
small, smooth and light to make them easily airborne
stigmas of wind pollinated flowers
feathery stigmas hang outside the flower to catch pollen in the air
filaments of wind pollinated flowers
long filaments to allow anthers to hang outside of the flower - easy removal of pollen
3 examples of wind pollinated flowers
grasses oak birch
fertilisation
the fusion of males and female gametes to form a zygote
first step of fertilisation
pollen grains land on the stigma and absorb a sugary material
what happens to each pollen during fertilisation
each pollen germinates to form a pollen tube that grows down to the style
what controls the growth of the pollen tube
the tube nucleus at the tip
what directs growth of pollen tubd towards the ovule
chemicals produced in the ovule (chemotropism)
how does the pollen tube enter the ovule and what happens when it does
via the micropyle and the nucleus breaks down
while the pollen tube enters the ovule, what happens to the generative nucleus
the generative nucleus divides by mitosis to form 2 male gamete nuclei
what happens to the male nuclei during fertilisation
the male nuclei move down the pollen tube and into the embryo sac