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Plant Diversity & Structure
General Characteristics Major Plant Groups Plant Evolution
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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
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Plant Groups Flowering plants Cone-bearing plants
Ferns and their relatives Mosses and their relatives Green algae ancestor Flowers; Seeds Enclosed in Fruit Seeds Water-Conducting (Vascular) Tissue 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
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There are two major groups of land plants which are separated based on their adaptations that enable them to survive on land: Non-Vascular Plants: Water enters plant directly through surface. They do not have roots. Rhizoids anchor plant. Example: moss Rhizoid Capsule Stalk Sporophyte Gametophyte Stemlike structure Leaflike structure 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. Thought Question: Which group of plants is more limited in terms of how large the individual plant can grow?
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The Diversity of Plants
Cone-bearing plants 760 species Flowering plants 235,000 species Ferns and their relatives 11,000 species Mosses and their relatives 15,600 species How has this diagram changed over the last 200 million years?
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Comparing Features of Seed Plants
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. Comparing Features of Seed Plants 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 Grasses, flowering trees and shrubs, wildflowers, cultivated flowers
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The Structure of a Flower
The reproductive structures of angiosperms are flowers. These structures all evolved as modifications of leaves. Filament Anther Stigma Style Ovary Carpel Petal Sepal Ovule Stamen 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.
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Compare/Contrast Table
Comparing Wind-pollinated and Animal-pollinated Plants Characteristics Pollination method Relative efficiency of pollination method Plant types Reproductive organs Adaptations that promote pollination Wind-pollinated Plants 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 Which pattern of macroevolution is demonstrated by this table? Why?
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Generalized Plant Life Cycle
What cellular process is illustrated here? Haploid Diploid ??????? 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. Spores (N) Gametophyte Plant (N) Sporophyte Plant (2N) Sperm (N) Eggs (N) FERTILIZATION
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Evolution of the Gametophyte and the Sporophyte
Gametophyte (N) Sporophyte (2N) Bryophytes Ferns Seed plants
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Review of Plant Evolution
Flowering plants Cone-bearing plants Ferns and their relatives Mosses and their relatives Green algae ancestor Flowers; Seeds Enclosed in Fruit Seeds Water-Conducting (Vascular) Tissue Thought Question: What is the evolutionary advantage associated with each of the derived characters shown in the cladogram below?
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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) 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 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 Habitat Wet, moist Tolerates drier conditions Widely adapted: Aquatic to desert
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Transpiration
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The Internal Structure of a Leaf
Cuticle Thought Question: What materials enter the stoma? What materials leave it? Veins Epidermis Palisade mesophyll Xylem Vein Phloem Spongy mesophyll Epidermis Stoma Guard cells
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Function of Guard Cells
Inner cell wall Inner cell wall Stoma Stoma Open Stoma Closed 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
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Water Cycle Condensation Precipitation Evaporation Transpiration
Runoff Seepage Root Uptake
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Transpiration Thought Question: How does water get “sucked-up” the plant? Does the plant have to work (use ATP) do this? Explain. A B Evaporation of water molecules out of leaves. Pull of water molecules upward from the roots.
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Pulling It All Together
3. 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?
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1. Overview 2. Light Dependent Reactions 3. Calvin Cycle
Photosynthesis 1. Overview 2. Light Dependent Reactions 3. Calvin Cycle
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Cellular Sunlight Radiant Carbohydrates Energy Cell (Stored Energy)
Respiration Sunlight Cell Activities ATP Light Energy Chloroplast C6H12O6 + O2 CO2 + H2O
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ADP ATP Adenosine diphosphate (ADP) + Phosphate
Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery
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Chlorophyll Chlorophyll is the type of pigment found in plants (pigments are molecules that absorb light). Absorption of Light by Chlorophyll a and Chlorophyll b Thought Questions: How does the wavelength of light absorbed and reflected by leaves related to the change of leaf color in the autumn? Chlorophyll b Chlorophyll a How does this relate to the pigments found in different types of algae at different depths of water? V B G Y O R
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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)
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Light-Dependent Reactions
Produce oxygen gas and convert ADP and NADP+ into energy carriers ATP and NADPH. These reactions take place within the thylakoid membranes of chloroplasts. Hydrogen Ion Movement Photosystem II Chloroplast ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma Electron Transport Chain Photosystem I ATP Formation
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Calvin Cycle Uses 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. CO2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated Factors Affecting Photosynthesis- Both temperature and the availability of water can affect rates of photosynthesis. Can you explain why? 6-Carbon Sugar Produced Sugars and other compounds
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Photosynthesis includes Light- dependent reactions Calvin cycle takes place in uses use take place in Thylakoid membranes Stroma NADPH & CO2 ATP Energy from Sunlight and Water to produce of to produce ATP NADPH O2 Chloroplasts High-energy sugars Thought Question: What factors will impact the rate of photosynthesis? What will cause the rate of photosynthesis to increase? Decrease?
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Essays 1. 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.
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