PLANT REPRODUCTION Chapter 43 Opener Amorphophallus titanium, also known as "corpse flower," has rarely been coaxed to bloom in the U.S. The central projection, called a spadix, is often over six feet tall and is filled with small male and female flowers.

Plant Reproduction What Are the Basic Features of Plant Life Cycles? How Is Reproduction in Seed Plants Adapted to Drier Environments? What is the Function and Structure of the Flower? Chapter 43 Opener Amorphophallus titanium, also known as "corpse flower," has rarely been coaxed to bloom in the U.S. The central projection, called a spadix, is often over six feet tall and is filled with small male and female flowers.

Terms to Know Haploid: having a single set of chromosomes in each cell. Diploid: having two sets of chromosomes in each cell. Mitosis: cell division, which produces two genetically identical cells. Meiosis: reduction division, which produces four haploid reproductive cells.

Plants and Animals Plant Reproduction Animal Reproduction Life cycle Alternation of generations No alternation of generations Gametes Haploid (n) gametes Haploid gametes Spores Haploid (n) spores No spores Gametes made by Haploid gametophyte, by mitosis Diploid organism, by meiosis Spores made by Diploid sporophyte, by meiosis

REPRODUCTION! 1:21 Asexual Reproduction Sexual Reproduction involves only 1 parent offspring genetically identical to parent involves regular body cells its quick Sexual Reproduction involves 2 parents offspring genetic mix of both parents involves specialized sex cells its slow 1:21

Asexual Reproduction Binary fission happens in bacteria, amoeba, some algae one parent cell splits into 2 identical daughter cells Budding happens in yeast, hydra, corals parent produces a bud bud gets detached and develops into offspring which is identical to parent

2 daughter cells are identical to parent Binary Fission Rod-Shaped Bacterium, hemorrhagic E. coli 2 daughter cells are identical to parent

Budding

Asexual Reproduction contd. Spore Formation happens in fungi, green algae, moulds and non flowering plants (e.g. ferns) spores are produced and each spore develops into offspring which are identical to parent Vegetative Reproduction does not involve seeds some offspring can grow from cuttings (e.g. coleus), runners (e.g. strawberries), tubers (e.g. potatoes) or bulbs (e.g. tulips)… which are part of the parent plant

Spore Formation Fern Fungi

Vegetative Reproduction

Sexual Reproduction in Animals involves specialized sex cells called gametes the union of a male and female gamete results in the formation of a zygote that develops into a new individual

Sexual Reproduction in Plants Female Parts Male Parts (Pistil) pollen (male) + ovule (female) → single-celled zygote → multi-celled embryo (contained in a seed) → new individual

Sexual Reproduction in Plants stamen is the male part and contains pollen carpels or pistil is the female part and contains ovule (eggs) pollen grains from the anther are transferred to the stigma by the process of pollination self pollination (plant pollinates its own eggs) cross pollination (pollen from one plant pollinates another plants eggs)

Pollination flowers are designed to lure insects to help with the pollination process also wind, animals, birds can transport pollen

Sexual Reproduction Summary Male Gamete Female Gamete Type of Union Result of Union Final Result Plants pollen ovule (egg) pollination single cell zygote multi-cell embryo (in seed) Animals sperm egg fertilization

Some Organisms do Both most plants that produce seeds (sexual reproduction) can also reproduce asexually by things like cuttings or runners this gives them an advantage for survival Mosses produce asexual spores in the early part of their life cycle and then egg and sperm cells are produced in a later part of the same cycle. sponges and hydra mosses

Which is Better? It depends! Asexual Reproduction advantages does not require special cells or a lot of energy can produce offspring quickly in a stable environment creates large, thriving population disadvantages limited ability to adapt face massive die-off if environment changes Sexual Reproduction advantages lots of variation within a species able to live in a variety of environmental settings able to adapt to changes in the environment disadvantages needs time & energy produce small populations

Asexual Reproduction Natural “cloning.” Genetically Identical. Fast, no mate required. Beneficial for plants that must compete for scarce resources (Stable Environs). Part of a single plant divides by mitosis to give rise to a new plants. Spreading of runners (strawberries) Production of bulbs (daffodils) Sprouting of rhizomes (irises)

Sexual Reproduction Fusion of egg and sperm cells (haploid), from meiosis, gamete formation and fertilization. May be limited to a certain season. Slower than asexual reproduction. Allows genetic mixing, increasing variability in a population. Two parents give rise to genetically variable offspring. Favored in variable environments.

Alternate “Generations” All plant life cycles are characterized by alternating of portions (haploid-to-diploid-to-haploid). Multicellular diploid plants (sporophytes) and multicellular haploid plants (gametophytes) take turns producing each other during the reproductive life cycle. Sporophyte: diploid (2n), produce haploid spores by meiosis. Gametophyte: haploid (n), produce gametes by mitosis.

Life Cycle

Life Cycle Diploid sporophyte (spore-forming plant) produces haploid spores by meiosis. Spore germinates (begins to grow and develop); divides repeatedly by mitosis forming a haploid gametophyte (gamete-forming plant). Gametophyte produces haploid sperm and eggs by mitosis (gametes are produced at different times to prevent self-fertilization).

Life Cycle Sperm and egg fuse to form a diploid zygote (fertilized egg). Zygote undergoes repeated mitosis to form a new diploid sporophyte plant.

Non-Flowering Plants Mosses, ferns, and related plants have motile, swimming sperm. Reproduction in these plants requires wet conditions, and requires having male and female parts close together. Living conditions, plant size, and genetic mixing is limited.

Moss and Fern Life Cycles

Group 1: Seedless, Nonvascular Plants Live in moist environments to reproduce Grow low to ground to retain moisture (nonvascular) Lack true leaves Common pioneer species during succession Gametophyte most common (dominant) Ex: Mosses, liverworts, hornworts

A. How Do Mosses/Liverworts Get Water? Nonvascular plant Only about 2 to 5 cm tall, cling to damp soil, sheltered rocks, and the shady side of trees Leaves have only one or two cells Rhizoids: root-like fibers that are on the outside; take in water from surroundings Continue on to next slide.

A. How Do Mosses/Liverworts Get Water? Spores: cells that can develop into new organisms (seedless) Close relative club mosses, horsetails, ferns, and spike mosses are VASCULAR They grow thick and tall Click this link to see pictures of moss and answer Question 1 on your sheet.

Continue on to next slide. Life Cycle of Mosses Asexual reproduction: a plant that needs only one type of cell to reproduce This process uses spores Sexual reproduction: a plant that needs two types of cells to reproduce This process completes the cycle to allow reproduction Continue on to next slide.

B. Life Cycle of Mosses Alternation of generations: process of going from asexual reproduction to sexual reproduction Click this link to learn more about what causes moss to grow and answer Question 2.

Moss Life Cycle

1)Moss gametophytes grow near the ground (haploid stage) 2) Through water, sperm from the male gametophyte will swim to the female gametophyte to create a diploid zygote 3) Diploid sporophyte will grow from zygote 4) Sporophyte will create and release haploid spores Diploid sporophyte . . . . . zygote egg egg zygote zygote egg egg zygote Haploid gametophytes male male female female female male female male

5) Haploid spores land and grow into new gametophytes 6) The process repeats . . . . . ground Haploid gametophytes

Haploid gametophytes . . . . . sporophyte male male female female zygote egg zygote egg egg zygote egg zygote Haploid gametophytes male male female female female male female male

Group 2: Seedless, Vascular Plants Vascular system allows Taller growth Nutrient transportation Live in moist environments swimming sperm Gametophyte stage Male gametophyte: makes sperm Female gametophyte: makes eggs Sperm swims to fertilize eggs Sporophyte stage Spores released into air Spores land and grow into gametophyte Ex: Ferns, Club mosses, Horsetails

Continue on to next slide. Parts of a Fern Fronds: the front leaves of ferns Rhizome: underground stem which ferns grow from; roots sprout from this Continue on to next slide.

Life Cycle of Ferns Reproduce by alternation of generation; just like mosses Fern seeds are on the fronds of the ferns and scatter on the ground Click this link to see the different types of ferns and the life cycle of a fern.

Fern Life Cycle

1) Sporophyte creates and releases haploid spores Adult Sporophyte . . . . ground

2) Haploid spores land in the soil . . . . ground

Fern gametophytes are called a prothallus 3) From the haploid spores, gametophyte grows in the soil Let’s zoom in Fern gametophytes are called a prothallus ground

4) Sperm swim through water from the male parts (antheridium) to the female parts (archegonia)…zygote created Let’s zoom back out zygote egg zygote egg zygote egg

Fern gametophytes are called a prothallus 5) Diploid sporophyte grows from the zygote sporophyte Fern gametophytes are called a prothallus ground

. . . . fiddlehead frond 6) Fiddle head uncurls….fronds open up 7) Cycle repeats -- Haploid spores created and released . . . fiddlehead frond . ground

2) Haploid spores land in the soil . . . . ground

3) From the haploid spores, gametophyte (called the prothallus) grows in the soil Let’s zoom in ground

4) Sperm swim through water from the male antheridium to the female archegonia Let’s zoom back out zygote egg zygote egg zygote egg

5) Diploid sporophyte grows from the zygote fiddlehead sporophyte ground

6) Fiddlehead uncurls….fronds open up. 7) Cycle repeats . . . . ground

Review Why do moss grow so low to the ground? Which stage is the main stage of moss: sporophyte or gametophyte? How do moss reproduce? What is the major difference between moss and ferns? What are the leaves of ferns called? What is needed for moss and ferns to reproduce? Which stage is the main stage of ferns: sporophyte or gametophyte? What stage is created when sperm and egg fuse: sporophyte or gametophyte? Name the gametophytes of ferns.

Conifer Pollination Conifers (also non-flowering plants) have reduced gametophytes. Male gametophyte is contained in a dry pollen grain. Female gametophyte is a few cells inside of the structures that become the seed.

Conifer Pollination Conifers are wind-pollinated plants. Chance allows some pollen to land on the scales of female cones. Pollen germinates, grows a pollen tube into the egg to allow sperm to fertilize the egg. Wind pollination is inefficient.

FIGURE 21-9 Life cycle of the pine The pine tree is the sporophyte generation (upper left) and bears both male and female cones. Haploid female gametophytes develop within the scales of female cones and produce egg cells. Male cones produce pollen, the male gametophytes. A pollen grain, dispersed by the wind, may land on the scale of a female cone. It then grows a pollen tube that penetrates the female gametophyte and conducts sperm to the egg. The fertilized egg develops into an embryonic plant enclosed in a seed. The seed is eventually released from the cone, germinates, and grows into a sporophyte tree.

Pollen In-between Showy flowers are the result of selection for more efficient pollination strategies. Flower parts are modified leaves. Those that were brightly colored attracted insects in search of pollen. Pollen itself is a protein- rich food for insects. Some plants offer other rewards, such as nectar.

Seed Plant Reproduction 43.2 How Is Reproduction in Seed Plants Adapted to Drier Environments? Seed plants (gymnosperms and angiosperms). Gametophytes develop within sporophytes. Reproduction can occur in dry habitats.

Seed Plant Reproduction Male gametophyte is surrounded by a protective coat called a pollen grain. The pollen grain encloses sperm cells in a watertight packet that can be easily transported to another plant. Egg-producing female gametophyte remains moist and protected within the sporophyte, and the pollen grain ensures that the sperm are delivered directly to the egg.

Seed Plant Reproduction The fertilized egg becomes enclosed in a drought- resistant seed. Consists of an embryonic plant and a food reserve encased within a protective outer coating. May lie dormant up to years waiting for conditions favorable for germination and growth.

Seed Plant Reproduction Non-flowering gymnosperms were the earliest seed plants. Gymnosperms bear male and female gametophytes on separate cones. Male cones release pollen grains that travel via wind to female cones.

Flowers

Sexual Reproduction - General Angiosperms produce flowers Flowers with both male and female reproductive organs are perfect flowers. Flowers that have only male or only female reproductive organs are imperfect flowers. Some angiosperms produce separate male and female flowers (imperfect flowers). Monoecious plants Dioecious plants

Angiosperms Sexual reproduction involves flowers and seeds. Flowering can be controlled by hormones, genes and/or environmental factors

Flower Parts

Flower Structure Evolution of the flower – purpose is attraction of pollinators. A change from radial to bilateral symmetry. Fusion or loss of whorls. Odors and colors. Nectar. Oddly shaped petals Flowers with 4 complete whorls = complete flower; flowers missing 1 or more whorls = incomplete flower.

Incomplete flowers Flowers are complete if they have all parts, and perfect if they have both male and female parts. Grass flowers: incomplete, usually imperfect (separate male and female flowers) A tulip is complete (though the sepals are the same color as the petals) and perfect.

Imperfect flowers

Angiosperm Life Cycle

Gametogenesis: Male

Gametogenesis: Female

Double Fertilization

Flower to Fruit

Ovule to Seed

Seed Germination