Lecture 15: Gymnosperms & Angiosperms Flashcards
parts of a seed
- megaspore
- megasporangium
- integument
- micropyle
megaspore
-spore that gives rise to a female gametophyte
megasporangium
- food source for developing embryo
- i.e. the fleshy part of a coconut
integument
- protects seed
- harden into the seed coat
- i.e. the hard part of a pumpkin seed
micropyle
-small opening to megasporangium
seed
-a plant embryo
three ways seeds are adaptive
- embryophytic
- dispersal (hard seed coat allows ability to disperse far from maternal plant)
- dormancy (allows seed to choose when to open and wait for a time of high resources/good environmental conditions)
homospory
- sporophyte produces a single type of spore
- i.e. ferns
heterospory
- mature sporophyte produces 2 types of sporangia (male and female)
- i.e. seed plants
microspore mother cell
- can be found in pollen cones
- inside male sporangia, mother cells with meiotically divide to make microspores
strobulis
-pollen bearing cones
microspore
- go through mitosis
- develop into pollen grain
pollen
- male gametophyte
- multicellular
sperm
-inside pollen grain cells undergo mitosis to make sperm
ovules
- seed bearing cones contain ovules
- will develop into seeds after fertilization
female gametophyte
- produces megaspores
- undergo meiosis to form 4 megaspores (female spores)
- ->only 1 is functional
- enclosed in protective tissue and dependent on sporophyte for nutrition
male gametophyte
- pollen grain
- produces microspores
- divide by mitosis to form pollen grain
naked seeds
- gymnosperms means “naked seed”
- seed not always wrapped in sporophytic tissue & gametophytic tissue is exposed to the outside
pollen tube
- allow delivery of sperm to egg cells
- grows mitotically from pollen grain
why aren’t seed plants dependent on water?
-because they’re good at dispersal and dormancy
types of gymnosperms
- cycads
- ginkgos
- gnetophytes
- conifers
cycads
- ancient, large
- slow growing
- motile sperm (swim down pollen tube)
- resemble palm trees
ginkgos
- only one extant species
- dioecious
- motile sperm
dioecious
-separate male and female individuals
female ginkgo biloba
- lost their cones
- have fruit
- have a horrible smell
male ginkgo biloba
-have papery cones
gnetophytes
- have vessel cells that homoplasious (convergence)
- types: gnetum, welwitschia, ephedra
vessel cells
- only gymnosperms to share a form of tracheid cells
- allows for efficient transfer of water & nutrients
welwitschia
- type of gnetophytes
- only base two leaves, cup shaped
- dioecious
- live in deserts
- long leaves
ephdera
- mormon tea
- many medical uses
- can lead to strokes
conifers
-most common gymnosperm
flower
- reproductive part of angiosperm
- evolved from leaves
traits of angiosperms
- develops flowers
- have fruit (used as seed nutrition and attraction for seed dispersion)
sepals
- flowers open out of this and hang below flower
- can be green
petals
- attract pollinators
- colorful
anthers
-site of microscopic or pollen production
filaments
-holds up anthers to be more accessible to pollinators or the wind
stamens
- anther filament combo
- male part
ovary
-houses ovules
ovules
-produces megaspores
style
-what the pollen tube has to go through in order to reach the flower
stigma
-site where pollen lands
carpel
-female part
apple anatomy
- apple forms a single carpel with interior seeds from many ovules
- ovary swells up and sugars develop making it tasty
- withered sepal on the bottom of apple
tomato anatomy
- true berry with fused carpels in ovary
- used to be 4 but humans removed 2 to dec. # of seeds
peas anatomy
- a fruit
- ovary doesn’t thicken
- ovules gain sugars and swell up around seed
- each seed has a sugary coat & the bean is the ovary
peach anatomy
- aka a drupe
- seed is inside the hard pit
blackberry anatomy
- many ovaries
- many carpels that form in a single flower that don’t fuse
- each bud on a berry is from a single ovary with a seed inside
pineapple
- compound/multiple fruit
- many flowers form on the parent plant on a single stem & as the seed develops, in each of the flowers the fruit fuses around into a single large fruit that contains many seeds
synergids
-cells that flank eggs when entering micropyle
antipodals
-on opposite side from the synergids in the ovule
polar nuclei
-two haploid nuclei in center of ovule
pollen tube
-contains tube cell and generative cell
tube cell
-makes pollen tube grow by dividing
generative cell
- undergo single meiotic division
- makes 2 functional sperm cells
double ferilization
-open sperm fertilizes egg(makes 2n zygote), the other fuses with the 2 polar nuclei (makes 3n endosperm)
3n endosperm
- rapidly divides
- forms the nutritional tissue
how is the angiosperm life cycle different than the gymnosperm life cycle?
- reduced cell number in female gametophyte
- faster speed of pollen tube growth
- double fertilization
- triploid endosperm
- fruit
what makes angiosperms so successful?
- their vessel cells
- rapid mutation
- pollinators
- fruit
