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Overview of Plant Diversity, Structure/Function, Reproduction, Responses and Adaptations

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  1. 1. Kingdom Plantae Overview of Plant Diversity, Structure/Function, Reproduction, Responses and Adaptations
  2. 2.  How many different kinds of plants can you count on the following slide?     A. 10 B. 17 C. 34 D. Too many to count….
  3. 3. D. Too many to count
  4. 4. 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. What are some items you use daily that are plant products?  2. What are three things plants need from animals, either directly or indirectly?
  5. 5. What is a Plant?  Plants are members of the Kingdom Plantae.     Most are autotrophic.   All are multicellular eukaryotes. All have cell walls made of cellulose. Carry out photosynthesis using green pigments chlorophyll a and b. A few are saprobic (decomposers) or parasitic. Ex: Trees, shrubs, grasses, mosses, ferns
  6. 6. What Plants Need to Survive   Plants are sessile…they don’t move around. This makes survival on land a difficult task. To be able to survive, they need:   1. Sunlight – they use energy from sunlight to carry out photosynthesis. 2. Water and Minerals – all cells require a constant supply of water. As plants absorb water, they also absorb minerals, which they need for growth.
  7. 7. What Plants Need to Survive   3. Gas Exchange – plants require oxygen to support cellular respiration as well as carbon dioxide to carry out photosynthesis. 4. Movement of Water and Nutrients – plants take in water and minerals through their roots, but make food in their leaves. They have to have specialized tissues to carry water upward and distribute products of photosynthesis throughout the plant body
  8. 8. Plant Diversity Cone-bearing plants 760 species Ferns & relatives 11,000 species Mosses & relatives 15,600 species Flowering plants 235,000 species
  9. 9. Reproduction Free From Water  Seed plants do not require water for fertilization of gametes.    This allows plants to live anywhere. Adaptations that allow this include: Cones and Flowers    The gametophyte grows within the cone or flower. Cones = Gymnosperms Flowers = Angiosperms
  10. 10. Reproduction Free From Water  Pollen    The entire male gametophyte is contained in a tiny structure called a pollen grain. The grain is carried to the female reproductive structure by wind, insects, or small animals. This transfer or pollen is called pollination.
  11. 11. Reproduction Free From Water  Seeds    A seed is an embryo of a plant that is enclosed in a protective covering that is surrounded by a food supply. An embryo is an organism in its early stage of development. A seed coat surrounds and protects the embryo.   This prevents drying out of the embryo. Seeds can be dispersed by wind, sticking to fur, or by being eaten and dispersed by animals.
  12. 12. Seed Structure Seed Coat Seed Embryo Wing Stored Food Supply
  13. 13. Eat Your Seeds!  A seed contains both the embryo of a plant and a food supply for that plant. If you have eaten corn, you’ve eaten a seed. Do you like hamburger buns with sesame seeds on them? That’s another kind of seed you’ve eaten.  After you answer the following questions, exchange papers with a partner to see how many of the same seeds you listed.
  14. 14.  1. In addition to sesame seeds, what are some other seeds that are found in or on top of loaves of bread?  2. In addition to corn, what are some other seeds that are eaten as “vegetables”?  3. What are some seeds that you have eaten as snack foods?  4. What types of nutrients are found in seeds?  5. Do seeds have the same nutritional value for plants as they do for animals? Why?
  15. 15. Gymnosperms – Cone Bearers    Gymnosperms are the most ancient surviving seed plants Conifers are the most common gymnosperms. These include pines, spruces, firs, cedars, sequoias, redwoods, and junipers.   Redwoods can grow more than 100 meters in height! Needle-like leaves are characteristic of this group, which is believed to have been evolved for dry, cool climates, and allows for water conservation.
  16. 16. Angiosperms – Flowering Plants   Angiosperms develop unique reproductive organs known as flowers. Advantage: attract animals such as bees, moths, or hummingbirds, which allows for efficient pollination. Helianthus annuus
  17. 17. Angiosperms – Flowering Plants    Flowers contain ovaries, which surround and protect the seeds. After pollination, the ovary develops into a fruit. A fruit is a wall of tissue surrounding a seed, which can be eaten by animals, and the seeds are dispersed after they pass through the animals digestive system.
  18. 18. Plants are categorized as Annuals Biennials Perennials that complete their life cycle in that complete their life cycle in that complete their life cycle in 1 growing season 2 years More than 2 years
  19. 19. Seed Plant Structure   Three of the principle organs of seed plants are roots, stems and leaves. 1. Roots – the root system of a plant absorbs water and dissolved nutrients.   Roots anchor plants to the ground, preventing erosion, and protects the plant from harmful soil bacteria and fungi. They also hold plants upright against wind and rain.
  20. 20. Seed Plant Structure  2. Stems – a stem has a support system for the plant body, a transport system that carries nutrients, and a defense system that protects the plant against predators and disease.   The stem must be strong enough to support branches and leaves. The stem must also contain subsystems that lift water and nutrients from the roots to the leaves.
  21. 21. Seed Plant Structure  3. Leaves – leaves are the plants main photosynthetic systems.  Leaves must contain subsystems that protect against water loss and conserve water, while allowing oxygen and carbon dioxide enter and exit the leaf. Stem Root Dermal Tissue Vascular Tissue Ground Tissue
  22. 22. Tissue Systems   Plants consist of three main tissue systems: dermal tissue, vascular tissue, and ground tissue. 1. Dermal Tissue – the outer covering of a plant consists of a single layer of epidermal cells.  These outer cells are often covered with a thick waxy layer called the cuticle.  Ex: Helps regulate water loss/gas exchange in leaves, increases surface area in roots and aids in water absorption.
  23. 23. Tissue Systems  2. Vascular Tissue – forms a transport system that moves water and nutrients throughout the plant. It has two main components:   A. Xylem – tissue that carries water upward from the roots to every part of a plant. B. Phloem – tissue responsible for the transport of nutrients and the carbohydrates produced by photosynthesis.
  24. 24. Tissue Systems  3. Ground Tissue – the cells that lie between the dermal and vascular tissues make up the ground tissue.  Photosynthesis occurs in the ground tissue of plants. Leaf Stem Root Dermal Tissue Vascular Tissue Ground Tissue
  25. 25. Types of Roots  The two main types of roots are taproots and fibrous roots.  1. Taproot – reach far underground for water.   Ex: Carrots, dandelions, radishes 2. Fibrous root – helps prevent erosion.  Ex: Grasses
  26. 26. Root Functions   Roots have 3 main jobs: 1. Uptake of Plant Nutrients - Nutrient Role in Plant Result of Deficiency Nitrogen Proper leaf growth and color; synthesis of amino acids, proteins, nucleic acids, and chlorophyll Stunted plant growth; pale yellow leaves Phosphorus Synthesis of DNA; development of roots, stems, flowers, and seeds Poor flowering; stunted growth Potassium Synthesis of proteins and carbohydrates; development of roots, stems, and flowers; resistance to cold and disease Weak stems and stunted roots; edges of leaves turn brown Magnesium Synthesis of chlorophyll Thin stems; mottled, pale leaves Calcium Cell growth and division; cell wall structure; cellular transport; enzyme action Stunted growth; curled leaves
  27. 27. Root Functions  2. Active transport of minerals – by using active transport to accumulate ions from the soil, cells of the root epidermis create conditions under which osmosis causes water to “follow” those ions and flow into the root.  The minerals then flow into the vascular tissue and are dispersed throughout the plant.
  28. 28. Root Functions  3. Root Pressure – as minerals are pumped into the vascular tissue, more and more water follows by osmosis.   This produces a strong pressure that keeps forcing water and nutrients in and up into the plant body, and prevents the roots from filling up and expanding with water. Without a constant root pressure, the stem and leaves would wither and die.
  29. 29. Stem Study  Imagine walking through a botanical garden. You probably would see many different kinds of plants, such as small and large trees, flowering plants, and cacti.  1. How do the stems of trees, flowering plants, and cacti differ? 2. How are the stems of these plants similar? 
  30. 30. Stem Structure and Function  Stems have three important functions:   They produce leaves, branches and flowers; they hold leaves up to the sunlight; and they transport substances between roots and leaves. Xylem and Phloem form continuous tubes from the roots through the stem to the leaves.  The stem allows for the entire body of the plant to be connected, so water and nutrients can reach the leaves.
  31. 31.    The region where the leaf branches off of the stem is called a node. The spaces in between nodes are called internodes. In flowering plants, buds form at the nodes in between the stem and the leaf. Node Internode
  32. 32. Formation of Wood    Most of what we call “wood” is actually layers of xylem. These cells build up year after year, layer upon layer. Tree growth is usually seasonal – light colored wood rings are called “early wood,” dark colored layers wood rings are called “late wood.” These names correspond with the times of year wood is formed, early and late in the year.
  33. 33. Formation of Bark     Bark includes all structures from the phloem to the outside of the tree. As the phloem grows to accommodate the needs of the growing tree, it forces other vascular tissues outward. The expansion causes the oldest tissues to split and fragment at they are stretched by the expanding stem. By the time these layers reach the outermost area of the tree, they are usually dead and cracked and look like the bark we all have seen on trees.
  34. 34. Layers of a Mature Tree Wood Bark Heartwood Phloem Meristem Tissue Xylem
  35. 35. Leaf Arrangements
  36. 36. Leaf Structure    The structure of a leaf is optimized for absorbing light and carrying out photosynthesis. The blade, the large flattened section, collects sunlight. The stalked petiole attaches the blade to the stem.
  37. 37. Internal Structure of a Leaf Cuticle Veins Epidermis Xylem Xylem Phloem Spongy mesophyll Epidermis Epidermis Stoma Stoma
  38. 38. Simple Leaves
  39. 39. Compound Leaves Acacia cornigera
  40. 40. Leaf Functions     There are three main functions of leaves. 1. Leaves are specialized structures for carrying out photosynthesis. 2. Leaves lose water through stoma in a process called transpiration. Lost water is replaced by water drawn in through the xylem. 3. Leaves are the site of gas exchange. They take in carbon dioxide and give off oxygen during photosynthesis
  41. 41. Water Transport  Water transport occurs in a plant due to the following processes:     1. A constant root pressure makes water transport possible 2. Capillary action causes the water to rise upward in the phloem. 3. Water is pulled through the stoma in the leaves in a process called transpiration. 4. Excess transpiration or low root pressure causes wilting, in which the stoma would then close to slow transpiration and build root pressure back up.
  42. 42. Evaporation of water molecules out of leaves. Pull of water molecules upward from the roots.
  43. 43. Nutrient Transport      We now know that transpiration pulls water upward through a plant. But most plant nutrients, including sugars, minerals, and organic molecules, are pushed through the phloem. Sugar movement flows from a source to a sink. The source can be any cell in which sugars are produced by photosynthesis. The sink is a cell where the sugars are used or stored. So….the sugars essentially move from where they are produced to where they are stored.
  44. 44. Flower Structure      Flowers are reproductive organs that are composed of four kinds of specialized leaves: 1. Sepals, 2. Petals, 3. Stamens, 4. Carpels. Stamen Anther Filament Ovule Stigma Style Carpel Ovary Petal Sepal
  45. 45. Flower Variation Nelumbo lutea Sabatia campestris Oenothera speciosa Helianthus annuus Centaurea americana Danaus plexippus on Cephalanthus occidentalis
  46. 46. Sepals and Petals    Sepals – the outermost circle of floral parts. Usually resembling leaves, they enclose the bud before it opens, and they protect the flower while it develops. Petals – the floral parts directly inside of the sepals. They are often brightly colored to attract insects and birds. Because these two groups are non-reproductive parts, they are sometimes called the sterile leaves.
  47. 47. Stamens and Carpels   Stamens – made up of the male reproductive parts, the filament and anther.  The filament is a long, thin stalk supporting the anther.  The anther is the site of meiosis, producing pollen. Carpels – also called the pistil, made up of the female reproductive parts.  The ovary is the site of meiosis, producing ovules.  The style is a narrow stalk, on which the stigma sits.  The stigma is the sticky portion on top of the style, where pollen grains land, and travel down the style to the ovary.
  48. 48. Comparing Wind-pollinated and Animal-pollinated Plants Characteristics Wind-pollinated Plants Animal-pollinated Plants Pollination method Wind pollination Vector pollination Relative efficiency of pollination method Less efficient More efficient Plant types Mostly gymnosperms and some angiosperms Angiosperms Reproductive organs Cones Flowers Adaptations that promote pollination Pollination drop Bright colors, sweet nectar
  49. 49. Pollination  Most gymnosperms are wind pollinated, whereas most angiosperms are pollinated by animals.    Ex: insects, birds, bats The work insect pollination would cost humans if we had to do it ourselves would cost billions of dollars a year. Botanists suggest that insect pollination is the factor largely responsible for the displacement of gymnosperms by angiosperms during the last 100 million years.
  50. 50. Seed Dispersal  Dispersal by animals – seeds contained in sweet, fleshy fruits are eaten by animals.  The tough coating of seeds protects them from digestive enzymes.  The seed sprouts in the nutrient rich feces of the animal, often in areas where there is less competition with the parent plants.
  51. 51. Seed Dispersal  Dispersal by wind and water – these seeds are typically lightweight, allowing them to be carried in the air or float on the surface of the water.   Wind examples: Maple seeds twirl as they fall from tree; tumbleweeds break off at roots and tumble across the plains. Water examples: Coconuts are buoyant and allow seeds to float.  Water dispersal is one reason for the success of this species reaching remote islands.
  52. 52. Seed Germination    Seed germination is the early growth stage of the embryo. When seeds germinate, they absorb water, causing the seed tissues to swell, which cracks open the seed coat. The young root them emerges through the crack and begins to grow, as the shoot grows in the opposite direction.
  53. 53. Different Types of Seeds Germinating Bean Corn Pea
  54. 54. Plant Responses   Tropism is the responses of plants to external stimuli. There are three main plant tropisms:  1. Gravitropism – the response of a plant to gravity.  This causes the shoot of a germinating seed to grow out of the soil – against gravity, and the root of the germinating seed to grow down into the soil – with gravity.
  55. 55. Plant Responses  2. Phototropism – the response of plants to light.   Causes the plant to grow toward a light source. This response can be so quick that young seedlings reorient themselves in a matter of hours. 3. Thigmotropism – the response of plants to touch. A plant that is touched often can become stunted in growth.  Vines twist as they touch objects and twirl around them to have something to anchor themselves to as they continue to grow. 
  56. 56. Phototropism Example Control Tip removed Opaque Cap Clear Cap Opaque Sheath over base
  57. 57. Photoperiodism Short-Day Plant  Photoperiodism in plants is responsible for the timing of seasonal activities such as flowering and growth.  Different types of plants flower more when exposed to differing amounts of light and darkness. Long-Day Plant Midnight Noon Long Day Midnight Noon Short Day Midnight Noon Interrupted Night Chrysanthemum Iris
  58. 58. Plant Adaptations  Aquatic Plants – able to tolerate mud that is saturated with water and nearly devoid of oxygen.  Expansive roots allow for maximum nutrient intake.  Seed pods float when mature and shoots grow very quickly after germination to reach the water’s surface Nelumbo lutea
  59. 59. Plant Adaptations  Desert plants – plant adaptations to a desert climate include extensive roots, reduced leaves, and thick stems that can store water.    Roots reach far into soil to reach water. Leaves sometimes modified into spines to reduce water loss. Thick stems allow for maximum water conservation.
  60. 60. Nutritional Specialists  Plants that have specialized features for obtaining nutrients include carnivorous plants and parasites.  Carnivorous plants, such at pitcher plants and Venus’ flytraps, trap insects and secret digestive enzymes that allow for absorption of the animal.  These plants usually live in bogs, or wet/acidic environments that allow for little nutrients in the soil. Pitcher plant Venus’ flytrap
  61. 61. Nutritional Specialists  Parasitic plants attach to a host plants and extract water and nutrients directly from the host plant.  Plants such as this attach to their host plant and can eventually kill the host as they leech all the nutrients and water out of the host. Cuscuta gronovii
  62. 62. Nutritional Specialists  Epiphytes – plants that are not rooted in the soil, but instead grow directly on the bodies of other plants – these are not parasitic.    Most are found in the rainforests. They gather their own water and nutrients in their specialized bodies. Over half of all orchid species are epiphytes.