Plant Biology Flashcards
4x evidence to indicate evolution from algae
- genome composition
- same type of chlorophyll
- cell wall composition
- sperm structure
Bryophytes
Non vascular plants
( Mosses, liverworts, hornworts )
Absorb water and nutrients through surface
Male bryophyte structures
Antheridium (contains sperm)
Female bryophyte structures
Archegonium (contains egg cells)
Fertilised bryophyte gametic cell
Zygote (2n)
Sporophyte produces…
Spores through meiosis
Bryophyte dominant life stage
Gametophyte (n)
Moss sporophyte structure, reproductive method and parts
Dependent on gametophyte
Sporoytes undergo meiosis to give haploid sprites
Capsule (top) and Seta (stalk)
Sterile columella (the central core)
NZ mosses
Around 500 species, 100 endemic
Predominantly Gondwanan origin
Spagnum moss
9 species
Occurs in dense colonies /peat bogs
Holds 30% of worlds stored carbon
Moss dormancy
Survival trait that allows them to easily shut down until they get favourable conditions
Liverworts
Differ to mosses in structure and spore dispersal
6500/7000 species
Gemmae cups
Drops of water hit raised cups on liverworts surface, splashing out pieces of tissue called gemmae, which can grow a new plant
Liverworts reproductive structures
Gametangia - umbrella like structures elevated about the thallus
Hornworts
300 species globally
Name refers to long shaped sporangia (sporophyte)
Bryophyte adaptions
- cuticle and stoma
- gametangia
- protection of spores
- protection of embryo (feed on the mother plant)
Innovations that led to Pteridophyte
Development of vascular tissue
Approx dates of pteridophyte evolution
430 - 387 mya
Xylem tissue
Moves water and minerals around the plant
One way
Phloem tissue
Moves sucrose and amino acids through a two way sap flow
Ferns
11916 species
2 types : Lycopodiopsida and polypodiopsida
Fronds can be divided or undivided
Fern stem
Rhizome, grows below soil surface
Fern sporophyte reproductive structures
Sporangium (store spores) attached to the Sorus (p. Sori) through Meiosis
Once spore lands, it germinates and develops into the gametophyte
Fern gametophyte (n) structures
Male - Antheridium
Female - Archegonium (both exist in the same plant)
Fertilised zygote undergoes mitosis to become young sporophyte
How does fertilisation of fern gametophyte occur
Antheridia swim through film on gamete to fertilise archegonia
Fern dominate life stage
Sporophyte (2n)
Gymnosperms
Naked seed, cone bearing plants
Cones are male or female
Plants can be male/female/hermaphroditic
Sporophyte life stage is dominant
Gametophyte is microscopic and dependant
Angiosperms
Encased seeds, bear flowers or fruit.
Flowers and plants can be male/female/hermaphroditic
Sporophyte life stage is dominant
Gametophyte is microscopic and dependant
Gametophyte location gymnosperms
Female gametophyte is within female seed/ovule cone
Male gametophyte is within pollen cone
Gametophyte location Angiosperms
Female gametophyte housed within female flower structures (carpal)
Male gametophyte housed within male flower parts (stamen)
Advantages of reduced gametophyte
Develops within parent plant - protection from UV, water loss, temperature
Easily supported by parent sporophyte - gains nutrients etc
Gymnosperm types
- Pinophyta / Coniferophyta (conifers)
- Ginkgophyta (Gingko)
- Cycadophyta (Cycads)
- Gnetophyta (Gnetophytes)
83 genera
Gymnosperm dominant life stage
Mature sporophyte
Cones structure
Modified leaves
Male - pollen cones, produce microsporangia which develops microgametophyte
Female - ovulate cones, produce megasporangia which develops megagametophyte
Stroboli
Conifer cone structure
Male cones
Have microsporangial tissue, produce micro spores through mitosis and then undergoes meiosis to become pollen structure (three celled)
Moves by wind to female cone
Female cone structure/process
Megasporangial tissue houses megasporocyte (2n), whichundergoes meiosis to produce megagametophyte material (megaspores, 4x produced but one survives)
Megastore goes through mitosis and develops into a female gametophyte and ovule, which then produces archegonia (contain one egg, n)
Integument
Outer woody structure on female cone parts
Gymnosperm fertilisation
Pollen is carried by wind to the female cone; pollen tube cell elongates through female gametophyte, allowing sperm to reach egg
Gymnosperm embryonic structures
- Cotyledon (seed leaves)
- shoot apical meristem tissue
- root apical meristem tissue + root cap
Diapause
Dormancy while waiting for correct conditions to grow and survive
Native pinophyta
4/8 conifer families have nz species
Eg Kauri, Kawaka, Totora, Rimu, Tānekaha, Toa Toa
Kauri trees
Agathis Australis, soil engineers so modify environment to suit them
Tānekaha
Phyllocladus trichomonoides
Mature specimens have no true leaves
Totora
Podicarpus Totora
Cones resemble fruit - bird dispersed
Rimū
Dacridium cupressinum
Fine leaves, ineffective individually but effective as a whole
Angiosperms
300,000 species, 400 families, 14,000 genera
Sepel
Modified leaves that protects flower when a bud and later petals
Petal
Modified leaves that help attract and guide pollinators
Stamen
Consists of a stalk (filament) and an anther (contains microsporangium - sperm)
Carpel
Consists of stigma, style and ovary. Contains megasporangia (eggs)
Receptacle
Thickened part of stem (penduncle( which flower organs grow from
Flower structures (outside in)
Receptacle, sepal, petal, stamen, carpel,
Fruit parts (+flower part)
- Endocarp (core, from ovary)
- Pedicel (stalk, from penduncle)
- mesocarp (fresh, from receptacle)
- Exocarp (skin)
- seed (from ovule)
Basal angiosperms
Relics of earlier groups of flowering plants
Monocotyledons
One seed leaf plants
Eudicotyledons
Two seed leafed plants
Cotyledons
First emerging leaves of a plant (not true leaves)
capable of photosynthesis and stores/supplies the nutrition a plant embryo needs to germinate and establish
Monocot features
- one cotyledon
- veins run parallel
- vascular tissue scattered
- root systems fibrous
- one pollen grain opening
- floral organs in multiples of 3
Eudicots
- two cotyledons
- veins netlike
- vascular tissue arranged in a ring
- taproot present
- pollen grain has three openings
- floral organs in multiples of four or five
Angiosperm dominant life stage
Sporophyte
Male gametophyte in angiosperms
Microsporangial tissue undergoes meiosis to produce microspores. These undergo mitosis to produce pollen structures
Female gametophyte in angiosperms
Megasporangial tissue within the ovule undergoes meiosis to produce a mega spore, which undergoes mitosis to produce 8 cells (which include an egg cell and 2 polar nuclei) within the megaspore
Double fertilisation
Pollen tube cell elongates down into the stigma to fertilise the egg
- sperm fertilises egg
- other spent fuses with the two polar nuclei to form the endosperm
Endosperm
Endosperm provides nutrients for the growing plant
True fruits
Fruits where the ovary tissue turns into the fruit
Diversity in angiosperms
- floral morphology
- pollen morphology
- pollination strategies
- dispersal strategies
Floral morphology
- number of whorls
- position of ovary
- symmetry
- inflorescences
Self pollination types
Autogamy - same flower
Geitogamy - different flower, same plant
Cross pollination
Allogamy- different plants
Plants avoid self pollination by
- Herkogamy
- Dichogamy
- placement of sexual structures
- pollen release
- gendered plants
Wind pollination features
- 10% of flowering plants
- flowers small grouped and unisexual
- large anthers with dry pollen
- large feathery or sticky stigma
Wind pollinated plants examples
- Zea mays (corn) seperate female and male flowers
- Coprosma Robusta
- Piper excelum (Kawakawa) female or male inflorescences
Animal pollinated plant features
- co-evolution
- conspicuous flowers
- more efficient
- uv nectar guides
Advantages for animals
- food
- nectar / pollen
- floral oils
- nursery pollination
Bird pollinated flower features
- prefer yellow or red flowers
- odourless flowers
- produce more nectar
- can change colour to indicate to birds eg fuchsia
Mammal pollinator example
Short nose bat and Dactylanthus taylorii
