Transcript Chapter 10: Plant Reproduction, Growth, and Development

Chapter 10: Plant
Reproduction, Growth, and
Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10-1
Sexual Reproduction in
Flowering Plants
Sexual reproduction requires gametes,
often as egg and sperm.
In flowering plants, the structures that
produce the egg and sperm are located
within the flower.
10-2
Flower structure
The reproductive
portions of a flower
are the stamen (male
part), consisting of a
filament and an
anther, and the pistil
(female part), made
up of stigma, style,
and ovary.
Sepals enclose a whorl of
petals that are usually
colored to attract
pollinators.
The ovary contains
one or more ovules.
10-3
Alternation of Generations
Fig 10.1
The sporophyte of
flowering plants is
dominant and
produces two types of
spores, microspores
and megaspores.
10-4
Alternation of generations in a
Fig 10.1
flowering plant
The sporophyte (2N)
produces haploid (N)
spores by meiosis.
A spore develops into a
haploid gametophyte
that produces gametes.
10-5
Fig 10.2
Sperm travel down the
pollen tube; one
sperm unites with the
egg and becomes a
zygote that develops
into an embryo.
The other sperm
unites with the polar
nuclei to produces
triploid (3n)
endosperm that
nourishes the embryo.
These two fusions are
known as double
fertilization.
10-6
The ovule wall hardens and becomes the
seed coat.
The seed consists of the sporophyte
embryo, stored food, and a seed coat.
The ovary may develop into a fruit.
10-7
Growth and Development in
Plants
Development is a programmed series of
stages from a simpler to a more
complex form.
Cellular differentiation is specialization
during development.
10-8
Development of a dicot embryo
after double fertilization Fig 10.3
Becomes
the Shoot
Store nutrients
taken from the
endosperm
Becomes
the Stem
Becomes
the Root
Seed
Leaves
10-9
The monocot embryo has
only one cotyledon that rarely
stores food.
10-10
Dispersal of Seeds
Seeds are modified to be distributed far
from the parent plant, by wind, animal
carrier, or by ocean currents.
10-11
Germination of Seeds
Germination of seeds occurs if there is
sufficient water, warmth, and oxygen to
sustain growth.
Dormancy may be required before
germination, and some seeds require
periods of cold or minimal moisture.
10-12
Common garden bean, a dicot
Fig 10.5
10-13
Corn, a monocot
Fig 10.6
The coleoptile and coleorhiza are protective sheaths
around the monocot plumule and radicle.
10-14
Asexual Reproduction in
Flowering Plants
Non-differentiated meristem tissue allows a
plant to reproduce by asexual vegetative
propagation.
In horticulture, identical offspring
produced by vegetative cuttings are
clones.
10-15
Propagation of Plants in Tissue
Fig 10.7
Culture
Plant cells are totipotent, having all the genetic
potential to become mature specialized plants.
10-16
Genetic Engineering of Plants
Various techniques introduce foreign
DNA into protoplasts that are
propagated in tissue culture.
10-17
Control of Plant Growth and
Development
Since each plant cell is totipotent,
hormones have a role in determining
cellular differentiation.
10-18
Plant Hormones
There are five common groups of plant hormones:
Auxins – promotes cell elongation and prevents
growth of axillary buds (apical dominance)
Gibberellins – promote growth of stems and can
break seed dormancy
Cytokinins – promote cell division
Abscisic acid – Stress hormone
Ethylene – ripens fruit and causes abscission of
leaves by increasing enzyme activity
10-19
Effects of plant hormones
Fig 10.9
Auxins
Gibberellins
10-20
Effects of ethylene
Fig 10.9
10-21
Plant Responses to
Environmental Stimuli
Plant growth and development are
influenced by environmental stimuli
such as light, day length, gravity, and
touch.
10-22
Positive phototropism Fig 10.10
Positive phototropism is
due to the migration of
auxin (stimulates cell
elongation) from the
bright side to the shady
side of a stem.
10-23
Negative gravitropism
Fig 10.11
In negative
gravitropism,
stems curve away
from gravity due to
auxin on the lower
side of the stem.
10-24
Flowering
Short-day (long night) plants flower when the
days get shorter than a critical length.
Long-day (short night) plants flower when the
days get longer than a critical length.
Day-neutral plants do not depend on day
length for flowering.
Phytochrome is a plant pigment believed to be
involved in regulating the response of plants
to day length.
10-25
Transport in the Mature Plant
Water and Mineral Transport in Xylem
Active transport
concentrates
minerals in root cells
and xylem.
Fig. 9.8
Water (and some
minerals) then
diffuses into the root
cells and forms
positive root
10-26
pressure.
Cohesion-tension theory of xylem transport
Fig 10.15
Transpiration,
evaporation of
water from
leaves, creates
a negative
pressure that
pulls the water
column
upward.
Polar water molecules are cohesive
and adhere to the walls of the xylem
vessel and fill the water pipeline.
10-27
Opening and Closing of Stomata
Guard cells on either side of a stoma
regulate its opening and closing, by
changing turgor pressure.
10-28
Pressure-flow theory of phloem
transport (translocation)
Sugar is actively
transported into
sieve-tube
elements and water
follows passively
and creates
pressure .
Sap moves to
‘sinks’ and sugar is
actively
transported out of
phloem
10-29
Adaptations of Roots for Mineral
Uptake
Plants are important for concentrating minerals
that are used by consumers including
humans.
10-30
Root nodules
Bacteria in the
root nodules of
legumes are
symbionts that
convert the
nitrogen in the
atmosphere to
NH4+.
10-31
Mycorrhizae
Mycorrhizae
increase water
and mineral
uptake and
improve
nutrient
transfer
10-32
Epiphytes (air plants) do not grow in soil
and therefore must use roots to extract
moisture from air and catch rain and
minerals in leaves.
Parasitic plants send out root-like
haustoria that tap into the xylem and
phloem of the host stem.
10-33