Topic 12 - Angisperms Flashcards
what is anthophyta?
- the flowering plants
- anthos = flower
-phyta = plants
How many phyla do angiosperms have?
- just one
- called anthophyta
what is a flower?
- a specialized shoot with
up to 4 whorls of modified leaves
Structure of a flower bottom to up:
Bottom
- sepals (non-reproductive)
- petals (non-reproductive)
-stamen is made up of a filament and an anther it is the male part (microsporophylls)
- carpels are made up of an ovary, style and stigma, it is the female part (megasporophylls)
what makes a pollen?
- anthers
how many ovules does the ovary at the base of carpel contain?
- 1 or more ovules
What is a perfect flower?
- contains both stamens & carpels, and
therefore is complete (= perfect), in
Linnaeus’ opinion
what is an imperfect flower?
- contains either stamens or carpels
– hence an imperfect flower is either a male
(has only stamens) or a female (has only
carpels)
what can be species be with imperfect flowers?
- monoecious
- mono = one
- oikos = house
- monoecious species have male and female
flowers on same individual plant
what can species also be with imperfect flowers?
- dioecious
– male and female flowers on
different individual plants (di = two)
what are angiosperms more reliant on?
- animal pollinators
what is the role of flowers to the angiosperms?
- flowers are often modified to attract them and dispense pollen
- flowers provide food rewards for animals that visit them and that
remove or deposit pollen
-the rewards are sugary fluids (nectar) or pollen itself
What are fruits?
- they are unique to angiosperms.
– mature ovary containing seeds
– the ‘container’ part of angiosperm (angio =vessel, container
what does carpos mean?
- fruit
In angiosperms, the megagametophyte is called?
- embryo sac which contains only 7 cells
- one of these cells have 2 nuclei which is called polar nuclei
what is double fertilization?
- one sperm nucleus fuses with egg nucleus –> 2n zygote
– other sperm nucleus fuses with the 2
megagametophyte nuclei called polar nuclei
– becomes triploid endosperm
what is unique in an angiosperms?
endopserm, take nutrients from
parent gametophyte
what does the endosperm repeatedly undergo?
- mitosis to
produce starchy food source for
embryo
what is a cotyledon?
- embryonic seed leaves
- it is inside the cell.
- you can have one or two
what are common names for the subdivision of Anthophyta
into groups called Monocotyla
and Dicotyla?
- monocots
and dicots
Steps of the Angiosperm life cycle?
- In the megaspornagium of each ovule, the megasporocyte divides by meiosis, producing four megaspores. One will survive and gives rise to a female gametophyte.
- on the anther each microsporangium contains microsporocytes that divide by meiosis, producing microspores.
- The microspore develops into a pollen grain. Th generative cell of the gametophyte will divide, forming two sperms. The tube cell will produce the pollen tube.
- after pollination, two sperms are discharged in the ovule.
- double fertilization occurs. one sperm fertilizes the egg, forming a zygote. The other sperm fertilizes the central cell, forming the endosperm.
- The zygote develops into an embryo and is packaged along with food in a seed. (embryo(2n), endosperm (3n), seed coat(2n)
- when a seed germinates the embryo develops into a mature sporophyte.
what is the first undeniable fossil of angiosperm?
†Archaefructis sinensis
when did rapid diversification of angiosperms occur?
- rapid diversification of angiosperms and
decline of many gymnosperm groups
occurred in Cretaceous and early Tertiary
what did Darwin view the appearance and dominance of flowering plants as?
- Darwin viewed the seemingly sudden
appearance and rise to dominance of
flowering plants in the fossil record as an
“abominable mystery”
Gymnosperms are not always wind pollinated, they an also be pollinated by?
- insects, or by both insects and wind
In some cycads where do the larvae develop?
- larvae of weevils develop in male cones where they feed on nonpollen tissues
what are adult weevils attracted to?
- sugary fluid produced by female
cones
what does a fertilized zygote nourish by?
pre-existing gametophyte cells
What do gentophytes undergo?
- something similar to
double fertilization - each of the two sperm in the pollen
grain gets to fertilize an egg
– but only one egg becomes zygote,
other one aborts
– as in other gymnosperms, zygote
nourished by pre-existing tissues of
female gametophyte (no endosperm
why is the angiosperm-style fertilization is more efficient than
gymnosperm-style?
-Beacuse:
- the food store for seed (endosperm) develops only
after fertilization
– hence no food resources are wasted if an egg is unfertilized
- and the female gametophyte (embryo sac) is reduced
in size and hence inexpensive and quick to produce
– production of the small female gametophyte takes only a
few days rather than months
what is most ancient living angiosperm?
Amborella trichopoda, which is both wind-pollinated and insect pollinated.
what are monocots upheld as?
monophyletic
what is one subset of of dicotyledonous
plants is monophyletic called?
eudicots, eu = true
What are the major morphological differences between monocots and eudicots?
Monocots:
- 1 cotyledons
-veins are parallel
- fibrous roots
- flowers parts in 3’s
Eudicots:
- 2 cotyledons
-veins are netlike
-taproot
-flower parts in 4’s and 5’s
Importance to Humans?
- we depend on angiosperms for most of our food
– 80% of calories consumed in world from 6 species: wheat, rice,
corn, potatoes, cassava, sweet potatoes
- some crops are grown for oil (corn)
- others for spices & flavourings (cinnamon)
- others as a source of extractable sugar (sugar cane)
- major source of drugs
Plant-Breeding to make more productive crop plants?
- compare size and number of kernels of teosinte
cob with domestic corn (maize)
Biotechnology is importnat because?
- transgenic golden rice contains genes from
daffodils that make beta-carotene (Vitamin A) - it increases the nutritive value of rice since beta-carotene is converted into vitamin A, which is essential for good vision.
