Presentation on theme: "KEY CONCEPT Plant life began in the water and became adapted to land."— Presentation transcript:
1 KEY CONCEPT Plant life began in the water and became adapted to land.
2 Land plants evolved from green algae. Plants and green algae have many common traits.both are photosynthetic eukaryotesboth have the same types of chlorophyllboth use starch as a storage productboth have cell walls with cellulose
3 Genetic analysis points to the common ancestor of all plants. extinct green algae species in class Charophyceaemodern charophyceans common in lakes and ponds
4 Important plant characteristics likely originated in charophyceans. multicellular body allowing for specialization of cells and tissuescell division that allows for chemical communication between cellsreproduction involving sperm swimming to egg
5 True plants evolved through natural selection. Ancestral charophyceans lived in areas of shallow water.Those that could survive longer dry periods were favored.First true plants probably grew at edges of water.True plants have embryos that develop while attached to female parent.
7 Plants have adaptations that allow them to live on land. Challenges of living on land have selected for certain plant adaptations.A cuticle allows plants to retain moisture.waxy, waterproof layerholds moisture in
8 Stomata are tiny holes in the cuticle. can open and closeallow air to move in and out
9 collection of specialized tissues A vascular system allows resources to move to different parts of the plant.collection of specialized tissuesbrings water and mineral nutrients up from rootsdisperses sugars from the leavesallows plants to grow higher off the groundsugarswater and mineral nutrients
10 Lignin allows plants to grow upright. plant cellsligninhardens cell walls of some vascular tissuesprovides stiffness to stems
11 Pollen grains allow for reproduction without free-standing water. pollen grains contain a cell that divides to form spermpollen can be carried by wind or animals to female structures
12 A seed is a storage device for a plant embryo. seed coats protect embryos from drying wind and sunlightembryo develops when environment is favorable
13 Plants evolve with other organisms in their environment. Plants and other organisms can share a mutualistic relationship.a mutualism is an interaction in which two species benefitplant roots and certain fungi and bacteriaflowering plants and their animal pollinators
14 Plants have adaptations that prevent animals from eating them. spines and thornsdefensive chemicals