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Angiosperms:The Flowering Plants

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Brief Phylogeny of Plants

Aquatic plants

Vascular plants Non-vascular plants

Seeded Plants Non-Seeded plants

Angiosperm Gymnosperm

Monocot Dicot This presentation will focus on angiosperms

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Angiosperms

Angiosperms are the flowering seed plants. Angiosperms have dominated the land for over 100 million years and there are about 250,000 known species.

Most of our foods come from a few hundred domesticated species of flowering plants.

Roughly 70% of angiosperms are polyploid.

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Flowering Plants

Some Grasses

Examples of AngiospermsDeciduous Trees (Trees that loose their leaves in a yearly cycle)

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Monocots and Dicots

The two main groups of angiosperms are the Monocots and the Dicots.

Monocot Dicot

The term monocot and dicot refer to the first leaves that appear on the embryo of the plant, the cotyledon.

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Examples of DicotsFruit Trees Grape Vines

Magnolia TreePumpkin Patch

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Differentiating Monocots and Dicots

Monocots and Dicots can be distinguished from each other by looking at a number of identifying traits.

These traits include seed leaves, leaf veins, stems, flowers, and roots.

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As we already mentioned, the cotyledon is an embryonic seed leaf, which is the first part of the plant to appear after it emerges from its seed.

Cotyledon

Monocot has one cotyledon

Dicot has two cotyledons

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Monocot Dicot

seed coat seed coat

endosperm endosperm

onecotyledon

two cotyledons

embryo embryo

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1 A dicot has one cotyledon.

True

False

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Monocots have parallel leaf veins

Leaf Veins

while dicots have branched leaf veins

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The vascular tissue which transports water and nutrients up the stem of the plant has different arrangements in monocots and dicots.

Stem Vascular Bundles

Monocots have bundles in complex arrangements

Dicots have vascular bundles in a ring

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3 This is the stem of a dicot.

True

False

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The floral petals on each plant differ in total number. Monocots have petals in multiples of three, while dicots have petals in multiples of four or five.

Flower Petal Arrangements

Multiple of 3Monocot

Multiple of 4 or 5Dicot

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4 Is this flower a monocot?

Yes

No

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5 This flower is a monocot.

True

False

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Monocots have a fibrous root system,

Roots

while dicots typically have one taproot.

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The adaptations allow plants to function on terrestrial habitats without drying out.

Adaptations

Plants need to absorb water and minerals from the soil, CO2 from the air, and light from the sun.

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Two main sections to the plant body: the roots and the shoots.

The plant body

shoots

roots

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The 3 functions of the root system are to:

(1) anchor the plant

(2) absorb and transport minerals and water

(3) store food

Functions of the Root System

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7 The main function of the root hair is to

A increase anchoring power of the plant

B increase surface area for absorption

C protect roots from freezing temperatures

D provide a passageway for nutrients

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The shoot system consists of the stems, leaves, and reproductive structures

Shoot System

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Stems are composed of nodes, where leaves, flowers, and other stems attach.

Space between the nodes is the internode.

Leaves are composed of photosynthetic blades and short stalks that attach at the nodes.

Parts of the stem

Leaf

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Buds are undeveloped shoots which have the potential to grow into nodes, internodes, and leaves.

Buds

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Terminal Buds are found at the top of the plant and are responsible for the growth in height.

Axillary (or lateral) Buds are found at each point of attachment for a leaf and the stem and are responsible for growth in width.

Types of Buds

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Apical Dominance results from the release of the hormone Auxin by the terminal bud which inhibits the growth from the lateral buds.

To made a plant bushier, you remove the terminal bud, which then allows for growth from the lateral buds. This is because the bud is removed, which means the hormone suppressing the growth is also removed.

Apical Dominance

This is also why pruning makes fruit trees produce more fruit.

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8 Removing the terminal bud of a plant will cause:

A an increase in the root system

B an increase in the size of the leaves

C increased axillary bud growth

D a plant to lose the ability to flower

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Based on their functions, many plants have modified structures.

Typical structures modified are roots, stems, and leaves.

Structural Modifications

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Many dicots have modified taproots.

Carrots, beets, turnips, and sweet potatoes are all roots modified for storage of carbohydrates.

The plants use the stored starches for flower production. This is why root crops are harvested before they flower.

Modified Roots

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A stolon is a modified stem who's purpose is to provide a means for asexual reproduction.

Rhizomes (like ginger) and tubers (like potatoes) are underground stems that store starch.

Modified Stems

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Spines offer protection

Tendrils are modified for grasping

Modified Leaves

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9 A stem modified for nutrient storage is called a

A taproot

B runner

C tuber

D bulb

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· many plant cells are photosynthetic and contain chloroplasts

· most plant cells have a large central vacuole that helps support the cell and keep it firm

· plant cells have a cell wall composed of cellulose that surrounds the plasma membrane

Review: Unique features of plant cells

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Review - Identify the parts of plant cells

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10 Which structure is found in both plant and animal cells?

A chloroplasts

B mitochondria

C cell walls

D all three are unique to plant cells only

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Everything always goes back to reproduction

"An oak tree is just an acorn's way of making more acorns"

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11 Review: Angiosperms are _______________ plants.

A cone-bearing

B vascular

C flowering

D seedless

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The Flower

The flower is the reproductive shoot of an angiosperm.

It is composed of modified leaves (petals, sepals, stamens, and carpels). The parts of a flower are both male and female.

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Structure of a Flower

Sepals are green and protect the flower buds.

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Structure of a Flower

Petals are large, colorful, showy, and used to attract pollinators.

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Structure of a Flower

Stamens are male structures with pollen-bearing anthers on the tip of a filament. The pollen grains deliver the sperm nuclei to the females.

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Structure of a Flower

Carpels are female structures composed of the stigma and ovary. Inside the ovary are the ovules which carry the developing egg and supporting cells.

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12 The male organ of the flower is the:

A style

B stamen

C carpel

D sepal

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13 In a typical flower, the parts that play the main role attracting animal-pollinators are the:

A petals

B fruits

C stigmas

D sepals

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14 The outer surface of a rosebud, before it opens up into bloom, consists of the:

A petals

B stamen

C ovary

D sepals

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15 In this picture of a lily, the arrow is pointing to the:

A stamen

B petal

C sepal

D stigma

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16 Review: look at photo and determine what type of angiosperm this flower is.

A monocot

B dicot

C vegetative

D fertilized

How did you determine that?

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Fertilization

· The development of pollen and ovules culminates in fertilization.

· All seed plants alternate between a diploid sporophyte generation that produce spores by meiosis and haploid gametophyte generation that produces gametes by mitosis.

· The gametes unite by fertilization to form a diploid zygote which is the first cell of the next sporophyte generation.

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Male GametophytesThe male gametophyte is the two-celled pollen grain. It undergoes meiosis in the anther and develops into spores. Each spore then develops mitotically to produce two haploid cells, a tube cell, and a generative cell.

The outer wall of the pollen grain is thick and resistant to damage.

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17 Which flower part produces male gametophytes?

A carpels

B anthers

C sepals

D stigmas

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Female Gametophytes

The female gametophyte develops inside the ovule.

One central cell undergoes meiosis and develops into a spore.

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The nucleus in the spore divides (through mitosis) and forms the embryo sac. This is the female gametophyte.

The embryo sac contains a large cell with two haploid nuclei.

The specialized ovary tissue at the base of the carpel also houses a haploid egg.

Female Gametophytes

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18 In the flowering plant, eggs are produced in the:

A stamens

B sepals

C ovules

D stigma

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Pollination

Pollen is usually wind or animal dispersed.

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Pollen Germination

Pollination occurs when the pollen from one flower is delivered to the stigma of another flower.

After pollination, the grain germinates and a tube cell grows in the pollen tube downward toward the stigma and ovary. The generative cell divides (through mitosis) and forms two sperm.

Once the tube reaches the ovule, it releases both sperm.

TED Talks : "The hidden beauty of pollina tion", Louie Schwartzberg (07:40)

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Double Fertilization

Fertilization occurs in the ovule.

One sperm fertilizes the egg forming a zygote (2n, diploid) which develops into the plant embryo.

The other sperm fuses with the 2 central nuclei in the ovule and forms a triploid (3n) nucleus which develops into the endosperm tissue which nourishes the embryo in the seed.

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19 In angiosperms, the process of _________ ensures that the endosperm will develop only in ovules containing a fertilized egg.

A cytogenesis

B meiosis

C mitosis

D double fertilization

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REVIEW Drag the names to label the Flower

stigmacarpel

anther

filamentstamen

petal

sepal

ovuleovary

style

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Ovule develops into a seed

Within the ovule, the diploid zygote divides, developing into the embryo.

With the first division, one cell becomes the embryo, the other cell becomes a thread that forces the embryo into the endosperm.

Near the end of maturation, the seed loses its water and develops a hardened seed coat.

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Seed Dormancy

Some seeds develop only to a point and then further development is suspended. The purpose of this is to allow time for dispersal.

Seasonal conditions also play a role in seed dormancy, with the plant only continuing its maturation when conditions are right. An example of this is chemical dormancy, wherein a seed contains substances (often hormones) to keep the seed dormant for a period. Once these chemicals are washed away (for example by snow melt or spring rains ) the seed can germinate.

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Monocot and Dicot Seed DifferencesRemember that seeds of dicots have 2 cotyledons which absorb endosperm nutrients and take over the role of nourishment.

The seed of a monocot is actually a fruit with one seed inside.

Corn seeds (the kernels) consist of a protective sheath, the embryonic root and shoot, and a large endosperm.

dicot

monocot

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Ovary develops into a fruit

The ovary of a flower changes into a fruit with the release of hormones following fertilization.

The fruit houses and protects the seed, as well as aiding with the dispersal.

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Pod Formation

There are 3 steps to pod formation in a plant 1. pollination takes place

2. petals drop from the flower and ovaries start to grow

3. ovaries form the pod (or fruit)

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Variations in Fruit

Fruits are very varied in organization

How many ovules, how many ovaries, how many carpels, how many flowers are involved and how the fruit is dispersed all account for the variations in fruits.

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Types of fruit

A peach is an example of a simple fruit.

A raspberry is an example of an aggregate fruit.

A pineapple is an example of a multiple fruit, one which develops from many united flowers.

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20 Flowers bear seeds in protective areas called:

A cones

B ovaries

C germination chambers

D sepals

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21 In the fully mature ovary, the vessel that houses the seed is the:

A ovule

B seed

C fruit

D cotyledon

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Dicot seed germination

In dicots, the root emerges first, followed by young seeds which exit the seed in a hooked shape that protects the meristem.

Once the shoot exits the soil, light stimulates the shoot to straighten and the first leaves develop and begin photosynthesis.

The cotyledons remain in the soil and decompose.

http://www.youtube .com/watch?v=d26AhcKeEbE

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22 Which of these structures is first to emerge from a germinating dicot seed?

A root

B hook shoot

C cotyledon

D root hair

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Monocot seed germination

In monocots, the root emerges first, followed by shoots that do not develop into a hook.

The shoots are protected by the abrasive soil by a sheath that surrounds them until they break through the surface.

The cotyledon remains in the soil and decomposes.

http://www.youtube .com/watch?v=iFCdAgeMGOA

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23 What eventually happens to the cotyledons of monocots and dicots?

A provide strength to the plant

B they form the leaves

C they remain in the soil and decompose

D they form the next ovule in the plant

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Asexual Reproduction - cloning

Vegetative propagation is the production of offspring from a single parent.

The offspring are called clones and are genetically identical to the parent.

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Asexual reproduction often involves fragmentation into separate parts, each part developing into a new plant.

A garlic bulb is an underground stem that will fragment into cloves, each developing into a new plant.

Asexual Reproduction - fragmenting

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Advantage to fragmenting

The advantage for this is each offspring is well suited to its immediate environment.

Fragmented offspring are less fragile than seedlings.

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24 Genetically identical organisms which result from asexual reproduction are called:

A clones

B seeds

C twins

D meristems

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25 Which plant part commonly contributes to asexual reproduction?

A fruits

B shoots

C roots

D stems

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Modern Agriculture

Many ornamental trees are propagated through asexual reproduction by leaf and stem cuttings

Propagation can also be done genetically through engineered plants (called GMOs - Genetically Modified Organisms)

The disadvantage to this is the crop plants which come from cloning have low levels of genetic diversity and they are easily devastated by disease.

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26 Which of the following shows the disadvantage to cloning as a propagation technique?

A its expensive

B its time consuming with slow results

C the plants can be easily wiped out by disease

D it requires a lot of farming space

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27 Foreign genes can be inserted into a plant cell and then cultured to produce:

A seeds

B genetically modified plants

C clones of the original plant

D plants that never die