introduction to plant life interest grabber plants make the world go round life as we know it today...
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Introduction to Plant Life
Interest Grabber
Plants Make the World Go Round
Life as we know it today could not exist without plants.Plants provide us with many essential items other than food.
1. With your partner, list five items you usedaily that are byproducts of plants.
2. With your partner, list three items that plants must get from animals—either directly or indirectly.
3. Using your answers to questions 1 and 2, construct a diagram that illustrates the interdependence of plants and animals.
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Introduction to Plant Life
Section Outline
Introduction to PlantsA. What Is a Plant?
B. The Plant Life Cycle
C. What Plants Need to Survive
1. Sunlight
2. Water and Minerals
3. Gas Exchange
4. Movement of Water and Nutrients
D. Early Plants
1. Origins in the Water
2. The First Plants
E. Overview of the Plant Kingdom
Section 22-1
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Introduction to Plant Life
What is a plant?
Dominant group of organisms on land (based on biomass)
Characteristics:
Size ranges from 2mm to 100 m tall.
Most are photosynthetic
Some are parasitic
Introduction to Plant Life
HaploidDiploid MEIOSIS
Spores(N)
Sporophyte Plant (2N)
Gametophyte Plant (N)
FERTILIZATION
Sperm(N)
Eggs(N)
Section 22-1Generalized Plant Life Cycle
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Introduction to Plant Life
Land plants evolved from green algae. • Plants and green algae have many common traits.
– both are photosynthetic eukaryotes – both have the same types of chlorophyll – both use starch as a storage product – both have cell walls with cellulose
Introduction to Plant Life
• Genetic analysis points to the common ancestor of all plants.
– extinct green algae species in class Charophyceae– modern charophyceans common in lakes and ponds
Introduction to Plant Life
• Important plant characteristics likely originated in charophyceans.– multicellular body allowing for specialization of
cells and tissues
– cell division that allows for chemical communication between cells
– reproduction involving sperm swimming to egg
Introduction to Plant Life
– Ancestral charophyceans lived in areas of shallow water.
• True plants evolved through natural selection.
– Those that could survive longer dry periods were favored.
– First true plants probably grew at edges of water.– True plants have embryos that develop while attached
to female parent.
Introduction to Plant Life
Plants have adaptations for life on land
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• Land plants are a clade, defined by a set of derived characters
– Alternation of haploid and diploid generations– Walled spores produced in sporangia– Male and female gametangia– Multicellular, dependent sporophyte embryos
Introduction to Plant Life
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• Life on land offered new opportunities– Unlimited sunlight
– Abundant CO2
– Initially, few pathogens or herbivores
Introduction to Plant Life
Copyright © 2009 Pearson Education, Inc.
• Challenges of terrestrial life– Maintaining moisture within cells– Obtaining resources from soil and air– Supporting body in air– Reproducing and dispersing offspring without
water
Introduction to Plant Life
• Challenges of living on land have selected for certain plant adaptations.
• A cuticle allows plants to retain moisture.– waxy, waterproof layer
– holds moisture in
Introduction to Plant Life
• Stomata are tiny holes in the cuticle.
stoma
– can open and close– allow air to move in and out
Introduction to Plant Life
• A vascular system allows resources to move to different parts of the plant.
sugars
water and mineral nutrients
– collection of specialized tissues– brings water and mineral nutrients up from roots
– disperses sugars from the leaves – allows plants to grow higher off the ground
Introduction to Plant Life
Copyright © 2009 Pearson Education, Inc.
Plant diversity reflects the evolutionary history of the plant kingdom
• Four key adaptations for life on land distinguish the main lineages of the plant kingdom
– Dependent embryos (characteristic of all plants)– Lignified vascular tissues– Seeds– Flowers
Introduction to Plant Life
• Lignin allows plants to grow upright.
– hardens cell walls of some vascular tissues– provides stiffness to stems
plant cells
lignin
Introduction to Plant Life
• Pollen grains allow for reproduction without free-standing water.
– pollen grains contain a cell that divides to form sperm
– pollen can be carried by wind or animals to female structures
Introduction to Plant Life
Copyright © 2009 Pearson Education, Inc.
• In all plants, the zygote develops into an embryo while attached to and nourished by the parent plant
• Plants are embryophytes, with multicellular, dependent embryos
Introduction to Plant Life
• A seed is a storage device for a plant embryo. – seed coats protect
embryos from drying wind and sunlight
– embryo develops when environment is favorable
Introduction to Plant Life
Plants evolve with other organisms in their environment. • Plants and other organisms can share a mutualistic
relationship. – a mutualism is an interaction in which two species
benefit– plant roots and certain fungi and bacteria – flowering plants and their animal pollinators
Introduction to Plant Life
• Plants have adaptations that prevent animals from eating them.
– defensive chemicals
– spines and thorns
Introduction to Plant Life
Spores
Flagellatedsperm
Stem Leaf
Seed
Pollen
Leaf
FernStomata; roots anchor plants,absorb water; lignified cellwalls; vascular tissue;fertilization requires moisture
Roots
Stem
Roots
Pine treeStomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue;fertilization does not require moisture
MossStomata only on sporophytes; primitive roots anchor plants,no lignin; no vascular tissue;fertilization requires moisture
Spores
Flagellatedsperm
Leaf
Stem
Roots
Flagellatedsperm
Vasculartissue
Key
Holdfast(anchors alga)
AlgaWater supportsalga. Whole algaperforms photo-synthesis;absorbs water,CO2, andminerals fromwater.
Introduction to Plant Life
Flagellatedsperm
Stem
Leaf
FernStomata; roots anchor plants,absorb water; lignified cellwalls; vascular tissue;fertilization requires moisture
Roots
MossStomata only on sporophytes; primitive roots anchor plants,no lignin; no vascular tissue;fertilization requires moisture
Spores
Flagellatedsperm
Leaf
Stem
Roots
Flagellatedsperm
Vasculartissue
Key
Holdfast(anchors alga)
AlgaWater supportsalga. Whole algaperforms photo-synthesis;absorbs water,CO2, andminerals fromwater.
Spores
Introduction to Plant Life
Leaf
Seed
Pollen
Stem
Roots
Pine treeStomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue;fertilization does not require moisture
Vasculartissue
Key