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Plant Evolution
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
• Challenge: Retain Moisture– Early plants grew near waters edge
• Solutions– Cuticle: waxy coating– Stomata: pores to allow gas exchange
cuticle
water
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
Land Adaptations
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
REview1) What traits do plants and plant-like protista (algae)
share?
2) Name 4 adaptations that plants have for life on land.
3) Which plant adaptation allows them to carry nutrients to great heights?
4) Which plant adaptation allows them to retain moisture?
5) What is the purpose of lignin?
6) Explain a symbiotic relationship between plants and other organisms?
7) How do plants protect themselves from predators?