Angiosperm reproduction Flashcards
Which reproductive features are unique to angiosperms?
Flowers, fruits, double fertilizations
What are the main phases of the alternation of generations?
Gametophyte: haploid (n) from meiosis of microspores and megaspores up to fertilization.
Sporophyte: diploid (2n) from fertilization up to production of spores by sporocytes.
what are microsporocytes and megasporocytes?
- Microsporocytes are microspores’ mother cells.
- Megasporoctyes are megaspore mother cells
How do gametophytes and gametophores relate to gametes?
- Gametophytes produce gametes in gametophores.
Where do microspores and megaspores begin?
- Microspores begin in pollen sacs in the anther where they are produced by microsporocytes
- Megaspores begin in the ovaries in the ovules where they are produced by megasporocytes.
What are some of the key features of macrogametes?
Plant ovaries contain ovules, the inner layer of which is an embryo sac or macrogametophyte. Ovules are attached to the placenta by a funiculus and covered with layers of integument which layer become seed coat when the ovules from seeds in the fruit. There’s a gap in the funiculus called a microphyle which allows sperm to enter to fertilise egg.
Eggs/macrogametes are produced by the macrogametophyte, and
Where are pollen grains?
Pollen grains stay in the anther until it dehisces.
What are the 4 parts of a flower?
- The calyx, the corolla, the androecium, the gynoecium.
Where is the flower on the plant?
The flower grows out of the apical or axillary bud on a pedicel (flower stalk).
What is a peduncle?
The peduncle is the main axis from which the pedicel connects to stem.
What are the three parts of a carpel?
the three parts of a carpel are the stigma, the style, and the ovary.
What are locules?
Locules are chambers of the ovary that contain ovules.
what is placentation?
Placentation is patterning of how seeds are attatched to the ovary
What are the parts of the stamen?
A stamen consists of an anther at the top of a filament.
How does germinates pollen get to ovary in a hermaphrodite flower?
Pollen in the anther moves down the style from stamens surrounding carpel to access the ovary containting 1+ ovules.
Monoecious vs hermaphrodite plants?
Monoecious: separate male flowers and female flowers on the one plant
Hermaphrodite: every flower on a single plant has both male and female parts.
Protoandry vs protogyny?
Protoandry: male gamete matures first
Protogyny: female gamete matures first
Haploid vs diploid?
Haploid: single copy of each chromosome
Diploid: paired copies of each chromosome
What are somatic cells?
Any cells but sex cells
Meiosis vs mitosis?
Mitosis in somatic cells; 2 diploid daughter cells
Meiosis in sex cells: 4 haploid daughter cells (genetic material halved) (two rounds of division)
Where does the haploid phase begin and end?
The haploid phase begins at haploid microspores/megaspores produced by diploid microsporocytes/megasporocytes
How does the anther release pollen?
The anther produces pollen through dehiscence
What happens when two haploid cells combine?
When two haploid (gamete) cells combine they form a diploid zygote.
What is the function of the stigma?
The stigma is the receptacle for pollen.
What is pollination?
Pollination is the transfer of pollen from an anther to a stigma.
how do you get from the megasporangium phase to the egg cell with 7 cells + 8 nuclei?
Diploid megasporocyte in the megasporangium undergoes meiosis to produce four megaspores, only one of which survives.
This one surviving megaspore undergoes miTosis 3 times with no cell division.
This produces a large cell with 8 nuclei.
This undergoes to form 7-celled embryo sac.
This includes 3 antipodal cells, 2 synergids, 2 polar nuclei (diploid) and 1 egg.
Egg cell becomes embryo once fertilized.
What is cytokinesis?
cytokinesis is division of the cytoplasm (mitosis: division of nuclear material)
How do you get from the microsporangium phase to the sperm cell?
Pollen sacs contain diploid microsporocytes which divide by meiosis to produce 4 haploid microspores.
Each microspore then undergoes miTosis to produce 2 cells: a generative cell and a tube cell (which engulfs the generative cell).
This generative cell undergoes miTosis to produce 2 sperm cells/microgametes.
What is a microsporangium?
Microsporangium is pollen sac, inner layer is tapetum, which breaks down to provide nutrients and wall material for pollen grain.
What are the three cells of the microgametophyte?
The microgametophyte consists of three cells: 2 sperm cells and a tube nucleus.
