What Is a Plant

1
What Is a Plant
2
Adapting to Life On Land

• First fossil evidence of plants 500 million
  years ago.
• Simple structures no leaves.
• Evolved from green algae.

3
Adaptations Preventing Water Loss

• Cuticle protective waxy layer around fruits,
  leaves, and stems.
• Prevents evaporation of water.

4
AdaptationsLeaves for Photosynthesis

• In filamentous green algae, all cells carry out
  photosynthesis.
• In plants leaves are specialized to make sugar.

5
AdaptationsRoots

• Plants must get water and nutrients from soil.
• Anchor plant in ground.
• Some act as storage organs.

6
Transporting Materials

• Water must move from root to leaves.
• Sugars must move from leaves to roots.
• Stem strong fibers allow upright growth.
• Also have tissues for transport of food, water,
  and minerals.
• Vascular tissues tube like cells.
• Some plants are nonvascular mosses, hornworts
  and liverworts.
• Water and nutrients move slowly by osmosis and
  diffusion.

7
Reproductive Strategies

• Some use seeds
• Embryo, food supply, protective coat.
• Protect from drying and aid in dispersal.
• Some use spores
• Single haploid cell with hard outer wall.
• Non-seed plants(mosses and ferns)
• Sperm swim through film of water to egg.
• Seed plants (conifers and flowering)
• Sperm (pollen) does not need to swim.

8
Alternation of Generations

• 2 stages
• Gametophyte (n)haploid makes gametes.
• Sporophyte (2n)diploid makes spores by meiosis.
  (Spores are haploid).
• Non-seed vascular plants (ferns)
• Spores release directly into environment and grow
  into haploid gametophytes.
• Seed plants
• Spores retained by parent plant and develop into
  gametophytes only a few cells in size.