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Diversity Part 2: Plants

Chapter 23 Introduction to Plants

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1. Autotrophs

2. Multicellular

3. Eukaryotes

4. Cell Wall is made out of Cellulose

Characteristics of Plants

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Chemical Equation:

◦CO2 + H2O C6H12O6 + O2

Word Equation:◦Carbon Dioxide + Water Glucose +

Oxygen

Photosynthesis

Sunlight

Sunlight

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The common ancestor of ALL plants is thought to be Green Algae

In the early evolution of plants, they made the transition from aquatic to land environments

Common Ancestor

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*Increased opportunity for photosynthesis*

Increased access to sunlight Increased access to carbon dioxide

Increased opportunity to reproduce and disperse (spread out)

But, decreased access to water as well…

How did plants overcome that barrier to successfully colonize on land??

Why Move onto Land?

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Mycorrhizae is a mutualistic relationship between plants and fungi to help a plant absorb water and nutrients from the soil.

This relationship helped plants transition to land.

Importance of Mycorrhizae

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Almost all plants have a cuticle covering their leaves and stems to prevent water loss

The cuticle is waxy (lots of lipids) and holds water in

  The cuticle is also clear to let sunlight in

for photosynthesis

Cuticle

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Once plants colonized land, certain adaptations allowed

them to reproduce and disperse their offspring

more effectively—this was the driving force for the

evolution of plants

Reproduction & Dispersal

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Cladogram

Bryophytes

Mosses

Green algae

Seedless vascular plants

Ferns

Gymnosperms

Evergreens

Angiosper

ms

Flowering Plants

Evolution of specialized cells / tissue

Evolution of cuticle

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1. Bryophytes (Seedless, Non-Vascular)-Mosses

2. Seedless, vascular plants- Ferns

3. Gymnosperms- Evergreens (Pine Trees)

4. Angiosperms-Flowering plants

Plant Groups

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Mitosis is a type of cell division that makes an exact copy of the original cell

Can be Haploid to Haploid or Diploid to Diploid

Meiosis is a type of cell division that makes cells with Half the number of chromosomes as the original cell

Can only be Diploid to Haploid

Plant Life Cycles:Alternation of Generations

An alternation between two distinct forms or generations that reproduce differently

One generation is haploid and reproduces sexually

The other generation is diploid and reproduces asexually

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Alternation of Generations

Multicellular diploid organism

(2n)

Unicellular haploid cells

(n)

meiosis

Unicellular diploid zygote

(2n)

mitosis

(spores)

Multicellularhaploid

organism(n)

mitosis

Unicellularhaploid gametes

(n)

fertilization

sporophyte

gametophytemitosis

Moss Life Cycle

Moss Life Cycle

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Alternation of Generations

By definition, all plants alternate generations

Gametophyte makes gametes

n=haploid

Sporophyte makes spores

2n=diploid16

Alternation of Generations Gametophyte and Sporophyte

Notice that the more advanced plants have a dominant Sporophyte

The less advanced plants have a more dominant Gametophyte

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Cladogram

Bryophytes

Green algae

Seedless vascular plants

Gymnosperms Angiosperms

Evolution of specialized cells / tissue

Example: cuticle

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Bryophytes

Example: Moss

Non-Vascular Plants

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They are small and low to the ground because they do not have vascular tissue

Found only in damp, moist areas on land

◦ 1) Leaves must absorb water for photosynthesis

◦ 2) Sperm swims through water to reach egg in gametophyte

Bryophytes

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Bryophytes

gametophyte

sporophyte

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Cladogram

Bryophytes

Green algae

Seedless vascular plants

Gymnosperms Angiosperms

Evolution of specialized cells / tissue

Evolution of cuticle

Evolution of vascular tissue

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Example: Ferns

Seedless Vascular Plants

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Vascular Tissue

◦ Set of tubes that transport materials around plant

◦ Allows plants to grow taller

◦ Water travels up through Xylem

◦ Sugar/Food travels throughout in Phloem

Key Adaptation over Nonvascular Plants

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Still must live in moist areas

Sporophyte grows successfully with vascular tissue

But sperm must still swim to egg in tiny gametophyte

Ferns Can Live Further Inland

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Fern Sporophyte

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Fern Gametophyte

Fern Life Cycle

Fern Life Cycle

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Cladogram

Bryophytes

Green algae

Seedless vascular plants

Gymnosperms Angiosperms

Evolution of specialized cells / tissue

Evolution of cuticle

Evolution of vascular tissue

Evolution of pollen grains / seeds

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Gymnosperms/Angiosperms

Example: Pine Trees or Flowers

Seed Plants

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Examples: Spruce Tree, Fir Tree, Pine Tree

Gymnosperms

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Gymnosperms Think cones (any conifer like pine trees)

female ovary

male pollen cone

Pine treeGymnosperms

tiny gametophyte inside cone

sporophyte

Sporophyte Dominates36

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Gymnosperm Pollen Strategy

Release a lot, hope some pollinate

(Meanwhile, irritating everyone else)

Pollen is the male sperm in Gymnosperms and Angiosperms

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Seeds

Pollen Grains

Key Adaptations Over Seedless Plants

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Tough coat protects newly fertilized embryo

Also contains supply of food (endosperm) to survive during dormancy period

A seed in a gymnosperm is inside the cone

Seeds

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Plants try to disperse offspring far away so they have a higher chance of survival.

Dispersal of seeds prevents competition for water, nutrients, light, and living space.

Seed Dispersal

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Dispersal by wind – wing-like structures, parachute-like structures

Seed Dispersal

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Dispersal by animals – fruits have hooks that cling on animals fur, other fruits provide food for animals

Seed Dispersal

Seed Dispersal

Seeds dispersal is completed by birds, small animals, wind, and water

The tough, fibrous outer covering of a coconut provides protection as well as a floatation device

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Hard covering around sperm, light weight allows travel by wind

Removes water requirement for fertilization

Pollen Grain

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At the very end when pollen lands on another plant of the same species

Pollen tube connects to ovary, fertilizing egg

Pollen Grain Sperm

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Cladogram

Bryophytes

Green algae

Seedless vascular plants

Gymnosperms Angiosperms

Evolution of specialized cells / tissue

Evolution of cuticle

Evolution of vascular tissue

Evolution of pollen grains / seeds

Evolution of flowers / fruits

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Angiosperms Think flowers Most diverse plant group Most Dominant Plant group on the planet

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Flowers

◦ Adapted for pollination by animals

◦ Attract animals to help carry pollen to the next flower

◦ Color or scent attractors guide animals to obtain sugar from plant

◦ Some angiosperms still wind pollinate (grass)

Key Adaptation Over Gymnosperms

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Advertising in UV color

Angiosperms are Divided intoMonocots and Dicots

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Monocots include: grasses, corn, rice, oats, wheat, orchids, lilies and palms

Dicots include: shrubs, trees (except conifers) wild flowers and some garden flowers

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Monocots

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Dicots

Monocot and Dicot Seed Structure

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Monocot and Dicot Leaf Veins

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Monocot and Dicot Flower Pedals

Monocot-pedals in groups of three or multiples of three

Dicots-pedals in groups of 4s or 5s

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Flower Structure of an Angiosperm

•Sepals protect the flower bud from insect damage and dryness

•The color, scent, and nectar of flowers attracts insects, bats, and birds

•These animals help to transfer the pollen from the anthers of one flower to the stigma of other flowers-called pollination

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SunflowerAngiosperms

tiny gametophyte inside bottom of flower

rest of plant = sporophyte

Sporophyte Dominates60

Pollen Tube Growth and Fertilization in Angiosperms

•The Pollen grains are transferred to the Stigma where the pollen grain produces a Pollen tube

•The pollen tube grows down the style into the ovary where it fertilizes the ovule

•The fertilized ovule becomes a seed and the ovary develops into the fruit of the plant

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The Sporophyte is the dominant stage in the life cycle of the

Angiosperms

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After fertilization, the ovary becomes the fruit and the ovule becomes the seed.

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Fruit

Typically collects sugar to attract animals

Seeds survive animal digestive system, pooped out far away from parent (and with free fertilizer!)

Some are not eaten by animals, just help wind carry seed ◦ Example: dandelion

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Cladogram

Bryophytes

Green algae

Seedless vascular plants

Gymnosperms Angiosperms

Evolution of specialized cells / tissue

Evolution of cuticle

Evolution of vascular tissue

Evolution of pollen grains / seeds

Evolution of flowers / fruits

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Asexual Reproduction Plants can also reproduce asexually

Vegetative reproduction is faster than sexual reproduction.

Vegetative reproduction is where many plant parts can grow to make a whole new organism when separated.

◦ Examples: Ivy or Potato

Ginkgophyta or “Ginkgo Tree”

A division of seed plants that have only one living species

The leaves of the plant are fan shaped

The Ginkgo is the oldest tree in the world, once thought to be extinct

Ginkgo’s are the lone survivor of a "family that existed more than 200 million years ago" and kept company with the dinosaurs

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The male trees are preferred because female trees bear a fruit which, after dropping, emits a foul odor. The fruit is about the size of a cherry tomato

Roasted nuts from Ginkgo biloba trees have long been considered a delicacy in their native China.

Treatment for short-term memory loss is just one of many medicinal uses for the extract derived from the leaves of Ginkgo biloba trees.

Ginkgo Tree