Transcript Inquiry into Life Twelfth Edition

Lecture PowerPoint to accompany
Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10.1 Sexual Reproduction in Plants
10.1 Sexual Reproduction in Plants
• Plants have two stages in their life cycle.
– A diploid stage alternates with a haploid stage.
• The diploid plant is called the sporophyte.
• The haploid plant is called the gametophyte.
10.1 Sexual Reproduction in Plants
• Flowers are the reproductive structures of
angiosperms.
• Flowers produce two kinds of spores.
– Microspores develop into the male gametophyte.
• The male gametophyte produces sperm.
– Megaspores develop into the female gametophyte.
• The female gametophyte produces an egg.
10.1 Sexual Reproduction in Plants
• Upon fertilization, a zygote is formed. The
zygote develops into an embryo.
• A seed forms contains the embryo and stored
food.
• When a seed germinates, a new sporophyte
emerges.
Alternation of Generations
in Flowering Plants
10.1 Sexual Reproduction in Plants
• Parts of a Flower
– Sepals - leaf-like structures that protect the
developing bud
– Petals - attract pollinators
– Stamens - male portion of the flower
• Anther - produces pollen grains
• Filament - a slender stalk that supports the anther
– Carpel - female portion of the flower
• Stigma - an enlarged stick knob
• Style - a slender stalk
• Ovary - encloses one or more ovules
Anatomy of a Flower
10.1 Sexual Reproduction in Plants
• Flower parts occur in
three’s (or multiples) in
monocots.
• Flower parts occur in four
or five’s (or multiples) in
eudicots
10.1 Sexual Reproduction in Plants
• Flowers may have
one or multiple
carpels (which may
be fused).
10.1 Sexual Reproduction in Plants
• Flowers that have sepals, petals, stamens and
carpels are called complete flowers. Flowers
that do not are called incomplete.
10.1 Sexual Reproduction in Plants
• A monoecious plant has
both staminate and
carpellate flowers. If
staminate and carpellate
flowers are on separate
plants, the plant is
dioecious.
10.1 Sexual Reproduction in Plants
• Life Cycle of Flowering Plants
– Flowering plants produce:
• Microspores
• Megaspores
10.1 Sexual Reproduction in Plants
• Life Cycle of Flowering Plants
– Microspores become mature male
gametophytes (sperm-bearing pollen grains)
– Megaspores become mature female
gametophytes (egg-bearing embryo sacs)
10.1 Sexual Reproduction in Plants
• Life Cycle of Flowering Plants
– During fertilization, one sperm nucleus unites
with the egg nucleus, producing a zygote.
– The other sperm unites with the polar nuclei,
forming a 3n endosperm cell.
Life Cycle of Flowering Plants
10.1 Sexual Reproduction in Plants
• Pollination – The transfer of pollen from an anther to a
stigma.
• Self-pollination (pollen is from the same plant)
• Cross-pollination (pollen is from a different plant)
Pollinators
10.2 Growth and Development
10.2 Growth and Development
• Development of the Eudicot Embryo
– The endosperm cells divides to produce endosperm
tissue.
– The zygote divides into two cells.
• One cell will become the embryo.
– Embryonic cells near the suspensor become the root, and
those at the opposite end form the shoot
• The other cell will give rise to the suspensor.
– The suspensor anchors the embryo and transfers nutrients to it.
Development of the Eudicot Embryo
10.2 Growth and Development
• Development of the Eudicot Embryo
– The embryo changes from a ball of cells to a heart-shape
– Cotyledons (seed leaves) appear
– The embryo next becomes torpedo-shaped, and the root tip and
shoot tip become visible
– The epicotyl portion of embryo contributes to shoot development
– The hypocotyl portion contributes to stem development
– The radicle contributes to root development
10.2 Growth and Development
• Monocots Versus Eudicots
– Eudicots (two cotyledons)
• Cotyledons store nutrients that the embryo uses
– Monocots (one cotyledon)
• Cotyledon absorbs food molecules from the endosperm and
passes them to the embryo
10.2 Growth and Development
• Fruit Types and Seed Dispersal
10.2 Growth and Development
• Fruit Types
– Fruits are derived from
an ovary
– Fruits protect and help
disperse offspring
– The ovary wall
thickens to become
the pericarp.
10.2 Growth and Development
• Fruit Types
– Simple fruits are
derived from a simple
ovary or from a
compound ovary.
•
•
•
•
Legumes
Dry fruits
Fleshy fruits
Accessory fruits
10.2 Growth and Development
• Fruit Types
– Compound fruits
develop from several
individual ovaries.
• Aggregate fruits
• Multiple fruits
10.2 Growth and Development
• Dispersal of Seeds
– Seeds may have hooks or spines that attach to fur or
clothing
– Seeds may pass through the digestive tract of
animals
– Seeds may be gathered and buried by animals
– Seeds may be carried by wind or water
10.2 Growth and Development
• Germination of Seeds
– Some types of seeds remain dormant until conditions
are favorable for growth.
•
•
•
•
Temperature
Moisture
Regulatory Factors (stimulatory and inhibitory)
Mechanical Action (examples: water or fire)
10.2 Growth and Development
• Eudicot Versus Monocot Germination
– Eudicots
• Cotyledons shrivel and degrade
• Epicotyl produces immature leaves and is called a plumule
• Young shoot is hook-shaped as it emerges through the soil
– Monocots
• Cotyledon does not have a storage function
• Plumule and radicle are protected by sheaths
• Plumule and radicle burst through the sheaths when
germination occurs
• Young shoot is straight, not hooked
Germination of Eudicots and Monocots
10.3 Asexual Reproduction
10.3 Asexual Reproduction
• Plants contain non-differentiated meristem tissue
that allows them to reproduce asexually by
vegetative propagation.
• Offspring may arise from the nodes of stolons or
rhizomes. Stems and roots can also give rise to
new plants.
10.3 Asexual Reproduction
• Tissue Culture
– The growth of tissue in an artificial liquid or solid
culture medium.
– Plant cells are totipotent, each cell can become an
entire plant.
– Large numbers of plants with desired characteristics
and genotypes can be propagated rapidly.
Tissue Culture of Plants
10.3 Asexual Reproduction
• Genetic Engineering of Plants
– Traditionally, different varieties of plants have been
crossed to produce offspring with desirable traits.
– Today it is possible to directly alter the genes of
organisms, producing new varieties of plants with
desirable traits.
– Plants that have a foreign gene are called transgenic
or genetically modified plants.
10.3 Asexual Reproduction
• Agricultural Plants with Improved Traits
– Corn, cotton, soybean and potato plants have been
engineered to be resistant to either herbicides or
insect pests.
– Ongoing research is expected to yield different variety
of crops that will be salt tolerant, cold tolerant,
drought resistant or blight resistant.
Transgenic Crops of the Future
10.3 Asexual Reproduction
• Commercial Products
– Single gene transfers have produced plants that can
manufacture various products
• Hormones
• Clotting Factors
• Antibodies
10.4 Control of Growth and Responses
• Hormones are small organic molecules that
serve as chemical signals between cells and
tissues.
10.4 Control of Growth and Responses
• Hormones are small organic molecules that
serve as chemical signals between cells and
tissues.
• Groups of Plant Hormones
–
–
–
–
–
Auxins
Gibberellins
Cytokinins
Abscisic Acid
Ethylene
Plant Hormones: Mode of Action
• Plant hormones bind to a
specific protein in the
plasma membrane. This
brings about a
physiological response.
10.4 Control of Growth and Responses
• Auxins
– Auxins affect many aspects of plant growth and
development. Auxins:
•
•
•
•
May promote apical dominance
Increase the development of adventitious roots
Promote the growth of fruits
Are involved with phototropism and gravitropism.
10.4 Control of Growth and Responses
• How Auxins Work
– H+ is pumped out of cells
– Auxins are acidic and weakens cell wall structure
– Water moves into the cell and turgor pressure causes
the cell to bend toward the light (away from auxin)
10.4 Control of Growth and Responses
• Gibberellins
– Gibberellins are
growth-promoting
hormones that
promote elongation.
10.4 Control of Growth and Responses
• Cytokinins
– Promote cell division
– Prevent senescence (aging)
– Initiate growth
– The ratios of auxins to cytokinins play a role regarding
the differentiation of plant tissues.
10.4 Control of Growth and Responses
• Abscisic Acid
– Produced by green
portions of plant
– Closes stomata and
maintains seed and bud
dormancy
– Considered a plant “stress”
hormone
– A decrease in abscisic acid
and an increase in
gibberellins breaks
dormancy
10.4 Control of Growth and Responses
• Ethylene:
– Is a gas that moves
freely through the air
– Is involved with
abscission (leaf drop)
– Promotes the ripening
of fruit
10.4 Control of Growth and Responses
• Plant Responses Are Influenced By:
–
–
–
–
Light
Day length
Gravity
Touch
10.4 Control of Growth and Responses
• Plant Tropisms:
– Phototropism:
Growth in response to light
– Gravitropism:
Growth in response to gravity
– Thigmotropism: Growth in response to touch
Positive
Phototropism
Negative
Gravitropism
10.4 Control of Growth and Responses
• Flowering
– Short-day plants
– Long-day plants
– Day-neutral plants
Photoperiodism and Flowering
10.4 Control of Growth and Responses
• Phytochrome and Plant Flowering
– Phytochrome is a plant pigment that responds to light
– Pr is active form; Pfr is inactive
– Direct sun contains more red light than far red light;
Pfr is present in plant leaves during the day
– At dusk, there is more far red light; Pfr is activated to
Pr
– Phytochrome conversion allows plant to detect
photoperiod changes
Phytochrome
Phytochrome Control of A Growth
Pattern