Plant Evolution • Evolved from green algae (450 mya) • Both have chlorophyll, store energy as starch, DNA similarities • Green algae ancestor • Multicellular body • Cells w/ channels to communicate • Reproduce w/ sperm & egg • Early plants • Low growth (nonvascular)
Land Adaptations cuticle • Challenge: Retain Moisture • Early plants grew near waters edge • Solutions • Cuticle: waxy coating • Stomata: pores to allow gas exchange
Land Adaptations glucose • Challenge: Transporting Resources • Solution: Vascular system: tissue to transport nutrients • Up from the roots (ex: water) • Down from the leaves (ex: sugars) • Allows taller growth water
Land Adaptations • Challenge: Growing upright • Large plants need to support own weight • Solution • Lignin: hardens cell wall; gives wood strength mortar lignin
Land Adaptations • Challenge: Reproduction on land • Solutions • Pollen: carried by wind/animals • Seeds: hard coat protects embryo inside
Alternation of Generations Plants alternate between a diploid organism and a haploid organism Sporophyte (diploid) Zygote created Zygote grows into adult sporophyte Sporophyte makes spores by meiosis Gametophyte (Haploid) Spore grows into a gametophyte Male gametophyte creates sperm Female gametophyte creates egg Sporophyte restarts when egg and sperm make zygote X X X X X
Plant Ecology • Mutualistic relationships • Type of symbiosis where both organisms benefit • Ex: Plants (provides living space)/Bacteria (create nutrients) • Ex: Plants (provide food)/Animal (help pollinate) • Herbivore interactions • Defense adaptations • Spines, thorns, chemicals
REview • What traits do plants and plant-like protista (algae) share? • Name 4 adaptations that plants have for life on land. • Which plant adaptation allows them to carry nutrients to great heights? • Which plant adaptation allows them to retain moisture? • What is the purpose of lignin? • Explain a symbiotic relationship between plants and other organisms? • How do plants protect themselves from predators?