Transcript Plants - Back to Basics

Plants - Back to Basics
 Why
are plants important?
 Plant
structures - from the
bottom up
 Plant
life processes - making
food and using energy
(respiration, photosynthesis,
transpiration)
Energy Flow
Energy reaches Earth
from the sun
(electromagnetic energy)
 Solar energy is
transformed into chemical
energy (sugars) by plants
 All animals ultimately rely
on energy captured by
plants

Roots





absorb water and minerals from soil
anchor plant in soil or other substrate
store food
xylem tissue transports water and
minerals from roots to other parts of
plant (xylem UP)
obtain sugars and other organic
nutrients from the leaves
Respiration
process by which
energy is released
from sugars
 requires oxygen
 plants take in oxygen
through their roots
for use in respiration

Stems
shoot = stem and
leaves
 nodes = where leaf is
attached to stem
 stem consists of
nodes and internodes
(segments between
nodes)

Stems, continued

terminal bud = point at tip of
shoot with developing leaves,
nodes and internodes

axillary bud = buds
at nodes; new
branches grow from
axillary buds
Modified stems
stolons = horizontal stems above
ground
 rhizomes = horizontal stems
below ground
 bulbs = vertical, underground
shoots (stems with modified
leaves)

Leaves
solar panels
 blade with petiole (stalk)
 petiole = joins the leaf
to a node on the stem
(grasses and some
other plants lack
petioles)

Leaf Arrangement

Simple leaf vs. compound leaf


simple, compound (palmate,
pinnate, doubly pinnate)
Venation

parallel, palmately net-veined,
pinnately net-veined
Leaf Shape
Deciduous = plants that drop all of
their leaves at one time once a year
 in response to seasonal changes
(temperature, precipitation)
 Evergreen = plants with green
leaves throughout the year
 leaves are shed and replaced
individually

Leaf anatomy
Photosynthesis
process by which plants make
sugars (convert sun’s energy into
food)
 takes place in chloroplasts
 uses carbon dioxide and water to
make sugars and oxygen
 phloem tissues transport sugars
to non-photosynthetic parts of the
plant (phloem DOWN)

Photosynthesis, continued
plants use sugars for food
(energy) and to make larger
molecules, such as cellulose
 plants store extra sugars as
starch
 most important process for life
on Earth

Photosynthesis vs. Respiration
Photosynthesis
Produces food
Respiration
Uses food for plant
energy
Releases energy
Stores energy
Occurs in cells that Occurs in all cells
contain chloroplasts
Releases oxygen
Uses water
Uses oxygen
Produces water
Transpiration

transpiration is the loss of water
from a plant through evaporation

transpiration drives the
movement of water, minerals and
nutrients through the plant
Transport from roots to stems
roots take in water and dissolved
minerals
 roots take in oxygen and give off
carbon dioxide
 water and minerals transported up
from roots by the xylem
 transpiration through leaves
(stomata) creates force that pulls
xylem sap upwards

Transport in stems and leaves
leaves take in carbon dioxide
and give off oxygen
 sugars created by
photosynthesis transported to
rest of plant by phloem

Plant reproduction

Reproduction in vascular plants
with seeds
 seed = embryo with stored
food in a protective covering
• 360 million years ago
 flowering plants = seeds in
protective chamber (ovary)
• 130 million years ago
Gymnosperms
seeds not in a protective
chamber (“naked seed”)
 most bear cones (pollen cones
and seed cones)
 conifers are the most diverse
group of gymnosperms

Gymnosperms
Alaska yellow-cedar
cycad
Douglas fir seed cone
Angiosperms
flowering plants =
seeds in a protective
chamber (ovary)
 two major divisions of
angiosperms:
 monocots
 dicots

Flowers
sepal
 petal
 stamen




filament
anther
carpel
(pistil)



ovary
style
stigma

fruit = mature ovary
Flowering plant life cycle
seed
germinating
seed
seedling
fruit
(develops
from ovary)
seed (develops
from ovule)
mature
plant
with
flowers
germinated
pollen grain on
stigma
pollen tube
ovary
ovule
Pollination  Fertilization

pollen grains attach to stigma

pollen contains sperm cells
pollen grain germinates
 pollen tube grows toward and into
the egg cell
 fertilization occurs when a sperm
nucleus unites with an egg nucleus
 cross-pollination vs. self-pollination

Banksia plants in Australia
Flowers
Fruit with seed pods open
Animals and Flowering Plants:
Adaptations

pollination


modified flowers
• insects
• small mammals
(esp. bats)
• birds
seed dispersal


carried
passed through digestive tract