Plant Diversity & Structure

1. General Characteristics

2. Major Plant Groups

3. Plant Evolution

General Plant Characteristics

• Multicellular

• Eukaryotic

• Cell walls made of cellulose

• Autotrophs (photosynthesis)– Use chlorophyll a and chlorophyll b

• Life cycle is characterized by alternation of generations

Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

Plant Groups

Green algae are thought to be the ancestors of plants

-similar size, color, and appearance

-Similar reproductive cycles

-Identical cell walls and pigments used for photosynthesis

There are two major groups of land plants which are separated based on their adaptations that enable them to survive on land:

Vascular Plants: have vascular tissue - internal tubes for transporting water and

minerals from the ground. Examples: fern, oak trees, roses, grasses, etc.

Cuticle: a waxy waterproof layer that prevents water being evaporated from plant.

Non-Vascular Plants: Water enters plant directly through surface. They do not have roots. Rhizoids anchor plant.Example: moss

Rhizoid

Capsule

StalkSporophyte

Gametophyte

Stemlikestructure

Leaflikestructure

Thought Question:

Which group of plants is more limited in terms of how large the individual plant can grow?

Cone-bearing plants760 species

Ferns andtheir relatives11,000 species

Mosses andtheir relatives15,600 species

Floweringplants235,000 species

The Diversity of Plants

How has this diagram changed over the last200 million years?

Comparing Features of Seed PlantsComparing Features of Seed Plants

Feature

Seeds

Reproduction

Examples

Feature

Seeds

Reproduction

Examples

Gymnosperms Angiosperms

Bear their seeds on cones

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Conifers, cycads, and ginkgoes

Bear their seeds within flowers

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Grasses, flowering trees and shrubs, wildflowers, cultivated flowers

GYMNOSPERMS - (gymn = naked, sperm = seed) Male cones produce pollen that travel to the female cones which contain ovules. Seeds develop uncovered on scales within the female cones.

ANGIOSPERMS - (angio = vessel, sperm - seed) Flowering plants produce their seeds using flowers. Many flowers have male and female organs. Seeds develop inside a protective, fleshy tissue called fruit. Many flowering plants rely on animals to pollinate them and some use wind pollination.

FilamentAnther

StigmaStyle

Ovary

Carpel

PetalSepal

Ovule

Stamen

The Structure of a FlowerThe reproductive structures of angiosperms are flowers. These structures all evolved as modifications of leaves.

Sepal - a whorl of modified leaves that protects the flower bud before it opens.

Petal - generally more brightly colored than sepals, advertise the flower to pollinators.

Stamen - The pollen producing male reproductive organ of a flower, consisting of an anther & a filament.

Carpel - The female reproductive organ of a flower, consisting of a stigma, style, & ovary.

Comparing Wind-pollinated and Animal-pollinated PlantsComparing Wind-pollinated and Animal-pollinated Plants

Characteristics

Pollination method

Relative efficiency of pollination method

Plant types

Reproductive organs

Adaptations that promote pollination

Characteristics

Pollination method

Relative efficiency of pollination method

Plant types

Reproductive organs

Adaptations that promote pollination

Wind-pollinatedPlants

Wind pollination

more pollen produced/ wasted, less decoration

gymnosperms and angiosperms

Cones or Simple Flowers

Pollination drop

Wind-pollinatedPlants

Wind pollination

more pollen produced/ wasted, less decoration

gymnosperms and angiosperms

Cones or Simple Flowers

Pollination drop

Animal-pollinated Plants

Vector pollination

less pollen produced/ wasted, more decoration

Angiosperms

Flowers

Bright colors, sweet nectar

Animal-pollinated Plants

Vector pollination

less pollen produced/ wasted, more decoration

Angiosperms

Flowers

Bright colors, sweet nectar

Compare/Contrast Table

Which pattern of macroevolution is demonstrated by this table? Why?

HaploidDiploid ???????

Spores(N)

Sporophyte Plant (2N)

Gametophyte Plant (N)

FERTILIZATION

Sperm(N)

Eggs(N)

Generalized Plant Life Cycle

The generalized plant life cycle is described as alternation of generations. This is a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte.

The gametophyte produces gametes.

The sporophyte produces spores.

What cellular process is illustrated here?

Gametophyte (N)

Sporophyte (2N)

Bryophytes Ferns Seed plants

Evolution of the Gametophyte and the Sporophyte

Review of Plant Evolution

Thought Question: What is the evolutionary advantage associated with each of the derived characters shown in the cladogram below?

Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

Moss + relatives

Fern + relatives

Gymno-sperms

Angio-sperms

Characteristic Features

No roots, stems, or leaves

Spores produced by sporangia, have underground roots & stems, leaves above ground

“gymn” - naked

Sperm” – seed

Seed is exposed

“ang” – vessel

“sperm” – seed

Seed is covered by fruit

Fertilization Thin layer of water; sperm swims to egg (ovule)

Thin layer of water; sperm swims to egg (ovule)

Some use swimming sperm, others use wind blown pollen

Some use wind-blown pollen, others use animal vectors

Dispersal of Offspring

Spores blown by wind or carried by water

Spores blown by wind or carried by water

Seeds blown by wind or carried by water

Seeds blown by wind, carried by water or spread by animals

Method of Getting Water and Minerals

Pores Roots & vascular tissue

Roots & vascular tissue

Roots & vascular tissue

Habitat Wet, moist Wet, moist Tolerates drier conditions

Widely adapted: Aquatic to desert

Transpiration

Veins

Xylem

PhloemVein

Cuticle

Epidermis

Palisademesophyll

Epidermis

Stoma

Guard cells

Spongymesophyll

The Internal Structure of a Leaf

Thought Thought Question:Question: What What materials materials enterenter the the stoma? stoma? What What materials materials

leaveleave it? it?

Stoma Open Stoma Closed

Guard cellsInner cell wall

Stoma

Guard cellsInner cell wall

Function of Guard Cells

•When water pressure is high, guard cells are forced into a curved shape and open the stoma

•When water pressure is low, the guard cells pull together and the stoma closes

•Photosynthesis = carbon dioxide in and oxygen out

•Cellular Respiration = oxygen in and carbon dioxide out

Condensation

Seepage

Runoff

Precipitation

TranspirationEvaporation

RootUptake

Water Cycle

Evaporation of water molecules out of leaves.

Pull of water molecules upward from the roots.

A B

Transpiration

Thought QuestionThought Question: : How does water How does water get “sucked-up” get “sucked-up” the plant? Does the plant? Does the plant have to the plant have to work (use ATP) do work (use ATP) do this? Explain.this? Explain.

Pulling It All Together3. Transpiration – the movement of water out of the leaf, “pulls” water upward by osmosis

2. Capillary action – the tendency of water to rise in a thin tube

cohesion – attraction between like molecules

adhesion – attraction between different molecules

1. Root pressure and active transport cause water to move from the soil into the root

What causes a plant to wilt?

Photosynthesis

1. Overview

2. Light Dependent Reactions

3. Calvin Cycle

Light Energy

Chloroplast

CO2 + H2OC6H12O6 + O2

Sunlight Cell Activities

ATP Cellular Respiration

Carbohydrates(Stored Energy)

Radiant Energy

ADP ATP

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

Absorption of Light byChlorophyll a and Chlorophyll b

V B G YO R

Chlorophyll b

Chlorophyll a

Chlorophyll is the type of pigment found in plants (pigments are molecules that absorb light).

Chlorophyll

Thought Questions:

How does the wavelength of light absorbed and reflected by leaves related to the change of leaf color in the autumn?

How does this relate to the pigments found in different types of algae at different depths of water?

Photosynthesis:Chloroplasts - bacteria sized organelle used for photosynthesis.

The light dependent reactions take place in granum.Granum - Stacks of thylakoids where the first half of photosynthesis takes place, (light-dependant reactions).

Stroma - The space around the thylakoids where the second half of photosynthesis takes place. (The Calvin Cycle)

HydrogenIon Movement

Photosystem II

InnerThylakoidSpace

ThylakoidMembrane

Stroma

ATP synthase

Electron Transport Chain Photosystem I ATP Formation

Chloroplast

Light-Dependent ReactionsProduce oxygen gas and convert ADP and NADP+ into energy carriers ATP and NADPH. These reactions take place within the thylakoid membranes of chloroplasts.

ChloropIast

CO2 Enters the Cycle

Energy Input

5-CarbonMoleculesRegenerated

Sugars and other compounds

6-Carbon SugarProduced

Calvin CycleUses ATP and NADPH from the light-dependant reactions to produce high-energy sugars. The Calvin Cycle takes place in the stroma of chloroplasts and does not require light.

Factors Affecting Photosynthesis- Both temperature and the availability of water can affect rates of photosynthesis.

Can you explain why?

Photosynthesis

includes

of

take place intakes place in uses

to produce to produce

use

Light-dependentreactions

Calvin cycle

Thylakoidmembranes Stroma NADPH & CO2ATPEnergy from

Sunlight and Water

ATP NADPH O2 Chloroplasts High-energysugars

Thought Question:

What factors will impact the rate of photosynthesis? What will cause the rate of photosynthesis to increase? Decrease?

Essays1.• a. Label letters A-J on the

diagram of flower parts.

• b. Even though plants have to expend a lot of energy to make flowers, why is it still an evolutionary advantage to have flowers? Use the terms pollinators, pollination, fruit, seed dispersal, reproductive success, physical appearance in your response.

2. The evolution of Plants and Animals on land are strongly linked, particularly when it comes to the evolution of insects. Explain how the evolution of the first plants 470 million years ago, and the first vascular plants 410 million years ago, is linked to a major change in animal evolution. Also, explain how the evolution of a new group of plants 150 million years ago (with an adaptive radiation starting 65 million years ago) has led to the types of plants and animals that are common today. Some key terms to incorporate include: open niches, mass extinction, coevolution, and mutualism.