plant reproduction Flashcards
draw and label a diagram of a typical flower
stigma, style, ovary, anther, filament, sepal, receptacle
what’s the function of the receptacle
part of the flower from which the flower part arises
what’s the function of the sepals
leaf like structures that protect the flower when it is a bud
what’s the function of the petal
to attract animals for pollination
define stamen
the male parts of the flower
define carpel
female parts of the flower
what’s the function of the filament
has vascular bundles to bring food wand water to the filament
what’s the function of the anther
produce pollen grains as a result of meiosis
what’s the function of the stigma
where the pollen lands
what’s the function of the style
through which the pollen tube grows
where is the embryo sack produced
ovule as a result of meiosis
describe the formation of a mature pollen grain
anther has 4 chambers called pollen sacs. in each pollen sac are diploid microspore pollen cells. these cells divide by meiosis to produce a cluster of 4 haploid cells called a tetrad. each tetrad breaks up to form 4 seperate haploid pollen grains. these pollen grains can divide by mitosis to produce two haploid nuclei (tube and generative)
describe the formation of the embryo sac
each ovary contains one or more ovules. one cell low down in the ovule is called hte megaspore mother cell, it is diploid and divides by meiosis to form 4 haploid cells. three of these cells degenerate. the remaining one is called the embryo sac. the haploid nucleus in this embryo sac divides by mitosis 3 times to form 8 haploid nuclei. 5 degenerate and the three remaining form the female gametes. two form the polar nuclei in the embryo sac, the other forms a cell wall and becomes the egg cell.
explain double fertilisation
one sperm nucleus joins with the egg nucleus to form a diploid zygote which will develop into an embryo. the second sperm nucleus joins with the two polar nuclei to form a triploid endosperm nucleus
define fertilisation
the union of male and female gametes to form a diploid zygote
explian the process of fertilisation
pollen grain lands on stigma and is stimulated to grow by hormones produced. the tube nucleus in the pollen grain forms a pollen tube down through the style to the ovule. tube nucleus degenerates once it reaches the micropyle. the haploid generative nucleus divides by mitosis to produce two sperm nuclei (male gametes) and then double fertilisation occurs
explain seed formation
fertilised ovule becomes the seed. integuments dry up and become the testa (wall of seed). the zygote divides by mitosis rapidly to give rise to the embryo which contains a radicle and plumule. some embryro cells form seed leaves. the endosperm nucleus also divides by mitosis to form many endosperm cells which absorb the nucellus and act as a food store
outline the main events in germination
seed absorbs water through micropyle and testa, activating enzymes. oils are digested to fatty acids/glycerol and starch is digested to glucose and proteins digested to amino acids. products of digestion moved to embryo. glucose and amino acids are used to create cell walls, enzymes and other structures. fats and some glucose are used in respiration. weight of seed decreases as weight of embryo increases. radicle bursts through testa, plumule emerges from the ground and leaves form.
