Bio Y2S2

• Basal Tree of life- Bryophytes- Lycophytes- Ferns- Gymnosperms- Angiosperms
• Life began 3700 million years ago- bacteria- Eoarchean period/archaean
• Green algae- Proterozoic- Mesoproterozoic- Ectasian- 1300 million years ago- First ancestor of plants
• Seed plants- Angiosperms- Gymnosperms
• Vascular plants- Angiosperms- Gymnosperms- ferns- Lycophytes
• Bryophytes- Hornworts- Mosses1- Mosses2- Liverworts- Mostly on the ground
• Plant evolution order- Green algae- Liverworts- Mosses- Hornworts- Lycophytes- ferns- Seed plants
• Angiosperm diversity- Largest- 270 000
• Gymnosperms diversity- 900
• Fern diversity- 12 000
• Lycophyte diversity- 1 200
• Hornworts diversity- 100- Smallest
• Mosses1&2 diversity- 12 000
• Liverworts diversity- 6 000
• Liverworts- oldest bryophytes- often flattened- short and close to the ground- reproduce with female structures or archegonia
• Reproduction through male structures- Antheridia- bryophytes
• Mosses- largest diversity of bryophytes
• Hornworts- smallest bryophytes- flattened body- reproduce via horns 
• Bryophytes have a very different life cycle compared to vascular plants
• Bryophytes lack vascular tissue- slower transport- less specialised internal cells- less strong
• Vascular tissues- Xylem- Phloem
• Xylem- Water transport- bottom up
• Phloem- top down- sugar transport
• Non-woody plant- herbaceous
• Vascular tissue in herbaceous plants- organised into islands, in a ring around the epidermis of the stem
• Xylem cells- very strong cell walls- acts as backbone, allows plant to grow taller
• Consequences of no vascular system- cell to cell passive water diffusion- no backbone to grow tall, max height of 10 cm
• Bryophytes lack roots- have rhizoids instead- good enough to anchor- bad for uptaking resources.
• Vascular system is active transport
• Bryophytes lack a cuticle- if the sun hits the plant, water evaporates- Can also take in water through the entire body instead of just the roots- can only survive in moist environments
• Cuticle- waxy layer- slows water loss- seals plant
• Specialised bryophytes in desert- can survive complete loss of water- can resume growth when water is received

   
• Bryophytes have imperfect adaptations- intake and lose water fast- do not transport water and nutrients very efficiently
• Alternations of generations- Haploid -> Diploid- switches at fertilisation or syngamy
• General life cycle- Meiosis -> Spores -> gametophyte -> gametes -> fertilisation -> Zygote -> embryo -> sporophyte
• Most common way to find bryophytes- gametophyte- Most long lived stage in bryophytes
• 2 versions of gametophytes in bryophytes- Antheridium, spermatozoids, 2 tails seeks the archegonium
• Antheridium is made up of- little flasks- called antheridia, these grow up and mature into the spermatozoids- once ripe, the antheridium will explode, releasing the spermatozoid- two flagella for propulsion, only moves in water, tiny amount
• Archegonium contain an egg cell- entrance at the top- many per plant
• Spermatozoids can only transfer to the archegonium in water- not a lot of water- taste in the environment for females