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 eukaryotes
both have the same types of chlorophyll
both use starch as a storage product
both have cell walls with cellulose

3. Genetic analysis points to the common ancestor of all plants.
extinct green algae species in class Charophyceae
modern charophyceans common in lakes and ponds

4. Important plant characteristics likely originated in charophyceans.
multicellular body allowing for specialization of cells and tissues
cell division that allows for chemical communication between cells
reproduction 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.

6. True plants evolved through natural selection.

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 layer
holds moisture in

8. Stomata are tiny holes in the cuticle.
can open and close
allow 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 tissues
brings water and mineral nutrients up from roots
disperses sugars from the leaves
allows plants to grow higher off the ground
sugars
water and mineral nutrients

10. Lignin allows plants to grow upright.
plant cells
lignin
hardens cell walls of some vascular tissues
provides stiffness to stems

11. Pollen grains allow for reproduction without free-standing water.
pollen grains contain a cell that divides to form sperm
pollen 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 sunlight
embryo 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 benefit
plant roots and certain fungi and bacteria
flowering plants and their animal pollinators

14. Plants have adaptations that prevent animals from eating them.
spines and thorns
defensive chemicals