Theme 3 - Plants PDF

Theme 3 - plants ---------------- - Origin of Earth = 4.6 Ga - Origin of life is approx 3.7-4 Ga - True colonisation began with fungi, early embryophytes and then animals 1. Desiccation → protection from drying out ( a coat or skin to prevent body fluids from evaporation) 2. Res...

Theme 3 - plants ---------------- - Origin of Earth = 4.6 Ga - Origin of life is approx 3.7-4 Ga - True colonisation began with fungi, early embryophytes and then animals 1. Desiccation → protection from drying out ( a coat or skin to prevent body fluids from evaporation) 2. Respiration → in water, there\'s dissolved oxygen and carbon which are exchanged so organisms needed to invent new structures to breathe 3. Reproduction → In water, eggs and sperms are released into the water. Land organisms have to evolve to become good reproducers under the desiccating conditions. 4. Locomotion → needs new features for animals and to defy gravity in plants 5. Senses: organism on land had to adapt to the changes of light, sounds and smell - Algal mats were first to come out and live on water edges - The first true fully terrestrial organisms were non-vascular plants - The first terrestrial animal was Arthropods - Desiccation - Growth erect - Apparatus to respire 1. Waxy cuticles a. Helps prevent them from drying out (water loss prevention) b. Has layers such as epidermal layer → outer cell c. The wax has fatty acids 2. Stomata d. Pores that allow exchange of gasses across leaf surface e. Opening and closing of pores controlled by specialized cells called guard cells i. Guard cells help with turgor pressure ii. Opening and closing depends on water or sunlight 1. Closed if no water in soil f. Found in earliest branches of land plants → non-vascular plants 3. Vascular tissue g. Cell walls that thickened with rings of lignin h. Vertical growth iii. Helps transport water by the elongated conducting cells iv. Maintain rigid polymer ring around it i. Has Xylem v. Dies at maturity j. Has tracheids = ferns and gymnosperm has vi. Opening in secondary wall k. Vessels = useful for angiosperms vii. Shorter but wider than tracheids 4. Root system l. Non-vascular plants (mosses)\--\> has rhizoids m. What stage will u see rhizord in vascular plants?\--\> fern gametophytes - Stomata was already in mosses (non-v) - vascular tissues with lignified cells and leaves evolved in lycophyte - non-swimming sperm and seeds evolved in gymnosperms 1. Evolutionary timeline 2. Water availability 3. Free living zygote Only in algae 4. Length of gametophyte (n) generation Algae \> mosses \> ferns \>conifer(gymno) (long) (short) 5. Length of sporophytes (2n) generation Algae \< mosses \< ferns \< conifer(gymno) 6. Relative size of gametophyte (n) 7. Relative size of sporophyte (2n) 8. Protection of zygote/embryo (2n)