Transcript What is a plant?

What is a plant?
Unit 7
Chapter 20
Plant characteristics
 Eukaryotic
 Multicellular
 Autotroph: food made through photosynthesis
 Cell walls made of cellulose
 Cuticle: waxy covering on plant body
 May have originated from green algae
Evidence for algal ancestry
 Cellulose cell walls in
algae and plants
 Same types of
chlorophyll for
photosynthesis and
stores sugar as starch
 Fossil record dated
440 MYO showed
plants without leaves
Adaptations to living on land
 Algae are mostly found in
water as they have no
adaptations to prevent
drying out on land.
 Plants have structures that
enable life on land.
 Roots
 Cuticle and waxy coats
 Protection for gametes
(sperm and egg)
Leaves
 Plant organ that
photosynthesizes
 May occur in other
plant parts with
chlorophyll (ex:
stems of cactus)
Roots
 Absorbs water and
minerals from soil
 Helps to anchor plants
to ground
 May store sugar
reserves (taproot)
Stem
 Transports water
and minerals from
roots to branches
and leaves
 Transports sugar
from leaves to
storage organs
 May store sugars
and water (ex: sugar
cane, cactus)
Xylem and phloem: specialized cells
that transport sugar and water
 Xylem and
phloem
make up
vascular
tissue
 Supports
plant life
away from
water
source
Xylem:
water
and
minerals
Phloem: sugar
Nonvascular plants: plants without
xylem and phloem
 Mosses, hornworts, liverworts
Nonvascular plants
 Simple
 Few cell layers thick
 Doesn’t need vascular tissue to transport
water and sugar because simple diffusion
suffices
Reproduction without water
 Algae require water to
transport sperm to egg
for fertilization.
 Land plants store food
with embryo within a
protective coat. This
forms the seed.
 Seeds are easily
dispersed and
protected from the
environment.
Food supply
Embryo
Seed coat
Seedless plants
 Sperm requires small water film to get to the
egg.
 Spores are formed instead of seeds.
Alternation of generation: plant life
cycle
Spores (n)
Male
gamete (n)
Female
gamete (n)
Gametophyte (n)
Meiosis
Fertilization
Sporophyte (2n)
Mitosis and
cell division
Survey of Plant Kingdom
Liverworts: nonvascular, seedless
Hornworts: nonvascular, seedless
Mosses: nonvascular, seedless
Whisk ferns: vascular, seedless
Club mosses: vascular, seedless
 Ancient club mosses
form the coal
reserves found today
Horsetails: vascular, seedless
Ferns: vascular, seedless
 Fronds: fern leaves with spores that grow
underneath
Cycads: exposed seed, vascular
Ginkgos: exposed seed, vascular
Welwitschia: exposed seed, vascular
Conifers: exposed seed, vascular,
bearing cones
Flowering plants: seeds within fruits,
vascular