Inquiry into Life Twelfth Edition Chapter 10 Lecture PowerPoint to accompany Sylvia S. Mader Copyright © The McGraw-Hill Companies, Inc. Permission required

Inquiry into LifeTwelfth Edition

Chapter 10

Lecture PowerPoint to accompany

Sylvia S. Mader

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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.


• 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.


• 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


• 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


• Flower parts occur in three’s (or multiples) in monocots.

• Flower parts occur in four or five’s (or multiples) in eudicots


• Flowers may have one or multiple carpels (which may be fused).


• Flowers that have sepals, petals, stamens and carpels are called complete flowers. Flowers that do not are called incomplete.


• A monoecious plant has both staminate and carpellate flowers. If staminate and carpellate flowers are on separate plants, the plant is dioecious.


• Life Cycle of Flowering Plants

– Flowering plants produce:• Microspores • Megaspores



– Microspores become mature male gametophytes (sperm-bearing pollen grains)

– Megaspores become mature female gametophytes (egg-bearing embryo sacs)



– 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


• 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


• 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


• 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


• 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


• Fruit Types and Seed Dispersal


• Fruit Types– Fruits are derived from

an ovary– Fruits protect and help

disperse offspring– The ovary wall

thickens to become the pericarp.


• Fruit Types– Simple fruits are

derived from a simple ovary or from a compound ovary.

• Legumes• Dry fruits• Fleshy fruits• Accessory fruits


• Fruit Types– Compound fruits

develop from several individual ovaries.

• Aggregate fruits• Multiple fruits


• 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


• 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)


• 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


• 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.


• 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


• 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.


• 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


• 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.


• 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.


• 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.


• 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)


• Gibberellins– Gibberellins are

growth-promoting hormones that promote elongation.


• Cytokinins– Promote cell division– Prevent senescence (aging)– Initiate growth

– The ratios of auxins to cytokinins play a role regarding the differentiation of plant tissues.


• 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


• Ethylene:– Is a gas that moves

freely through the air– Is involved with

abscission (leaf drop)– Promotes the ripening

of fruit


• Plant Responses Are Influenced By:– Light– Day length– Gravity– Touch


• Plant Tropisms:– Phototropism: Growth in response to light

– Gravitropism: Growth in response to gravity

– Thigmotropism: Growth in response to touch

Positive NegativePhototropism Gravitropism


• Flowering

– Short-day plants

– Long-day plants

– Day-neutral plants

Photoperiodism and Flowering


• 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

Documents

Inquiry into Life Twelfth Edition Chapter 10 Lecture PowerPoint to accompany Sylvia S. Mader Copyright © The McGraw-Hill Companies, Inc. Permission required