Plant Biodiversity

• Plants living on land need to develop adaptive traits:

  • waxy cuticle to reduce water loss
  • Stomata for gaseous exchange
  • True root ,stems and leaves to absorb water and nutrients and to distribute materials to all parts of the plant and provide support
  • Vascular tissue(xylem and phloem) used for support and transport
  • Method of reproduction to germinate and reproduce
  • Dependance on water for dispersal and reproduction
• Vascular tissue made up with xylem and phloem
• Male gametes swim to the female gametes in water
• Thallus plants no true root stems and leaves (Bryophytes)
• Bryophytes are primitive land plants(live in damp, shady areas)
• Structures and characteristics of moss plant (Bryophyte):

  • No vascular tissue rely on Diffusion
  • lack of vascular tissue limits size
  • rhizoid(Root like structure) Anchors plant , absorbs water and mineral salt from plant
  • 'Leaves' small and one cell layer thick ,lack cuticle ,water can be lost from entire body, contains chlorophyll and photosynthesis
• Moss plant has 2 phases of life cycle:

  1. Gametophyte generation : male and female organs produce gametes, water used for fertilization(sexual)
  2. Sporophyte generation :Spores are produced(asexual)
• bryophyte reproduction :

  • moss plants have 2 phase life cycle
  • Wet conditions sperm swims to ova to fertilize it
  • fertilized ova(zygote) grows on top of female branch
  • sporophytes made up of foot , seta and capsule
  • spores mature calyptra breaks and spores released
  • spore germinates in to protonema
  • Water essential for sperm to flow to ova (Bryophytes)
• foot absorbs water and mineral salt from gametophyte
• seta hold capsule upright for spore dispersal over a greater area
• pterophytes are reliant on water for certain aspects of life cycle
• Structure and characteristics of ferns(pterophytes) :

  • They have vascular and strengthening tissue
  • leaves are covered in waxy cuticle live in a wider variety of area than mosses
  • Gametophyte generation is prothallus , sperm(male) swims to ova(female) for fertilization
  • sporophyte generation produces spores(asexual)
• Pterophyte reproduction:

  • Mature pinnae are called sori
  • sorus(singular) produce many sporangia that produce spores
  • When spores are mature ,sporangia opens and flings out spores
  • They are dispersed by wind(vector) and germinate in a suitable habitat
  • spores grow into heart shaped structure(prothallus)
  • sperm swims to ova in film of water
• Spermatophytes are spilt into gymnosperms(naked seeds) and angiosperms(flowering plants)
• Seeds have protective coat (testa)
• Gymnosperms(Naked seeds) : conifers are the most diverse group of gymnosperms
• structure of pine tree

  • Has true root , stems and leaves
  • Has conducting and strengthening tissue
  • grows into large trees (sporophytes)
• structure of pine tree

  • Has true root , stems and leaves
  • Has conducting and strengthening tissue
  • grows into large trees (sporophytes)
  • Stem protected by bark called rhytidome
• In pine trees transpiration is minimized by :

  1. reduced surface area of needle shaped leaves

  2. thick cuticle

  3. Sunken stomata
• Reproduction (Gymnosperms) :

  • produce male and female cones
  • male cones - pollen grains , male gamete
  • Mature pollen grains dispersed by wind (Not dependent on water for fertilization)
  • female cone (ova)
  • fertilization occurs when male cone fuses with ovum (female cone)
  • zygote forms embryo enclosed in seed
  • wing like structure aids in the dispersal
  • enclosed within a fruit (naked seed)
• Adaptations of Pinus :

  • tap root system for anchorage and absorption of water and mineral salt
  • mycorrhiza assists in water and mineral salt absorption
  • stem has bark
  • stem has conducting and strengthening tissue
  • needle shaped leaves reduce water
  • thick cuticle reduces water loss
  • gametes protected by cone
  • pollen grains are light and has air sac which allows for dispersal by wind
  • seeds have testa which prevents dying out
  • seeds have endosperm which provides nutrients to germinating embryo
• Angiosperms are vascular plants and are the only plants that produce fruit and flowers
• flowers have male and female reproductive organs
• ovule matures into seed and ovary becomes fruit
• Characteristics of angiosperms :

  • pollination ensures water not needed for fertilization
  • Fruit aids in dispersal of seeds
  • Sporophyte dominate and gametophyte reduceds
• Reproduction in angiosperms :

  • independent of water
  • anthers(male gamete) produces pollen
  • transferred from anthers to stigma by pollinating agents
  • female parts are the stigma , style , and ovary(one or more ovule)
  • ovule produces ovum (female part)
  • zygote develops in embryo
  • ovule develops into seeds
  • ovary develops into fruits
• Adaptations of angiosperms :

  • pollen grains produced for pollination
  • Petals brightly colored to attract agents of pollination
  • Nectaries produce sugary nectar which attracts birds and insects
  • stigma sticky and hairy (adheres pollen)
  • pollen grains are small and light easy for pollinating agents to transport , produced in large numbers
• Bryophytes :

  • thallus
  • gametophyte dominate
  • no seeds only spores
• seeds as a food source :

  • cereal
  • energy requirement for staple diet
• Seed banks :

  • urbanization , farming practices and human pollination growth (reason why we need seed banks)
  • seed banks conserve seeds from all species
  • seeds from all over the world sent to sed banks
  • endangered plants are protected and reintroduced to environment
  • under the right environmental conditions they are left dormant
• endemic : only found in one place