Life Cycle and Reproductive Structure
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This document provides an outline and objectives for a lesson on life cycles and reproductive structures in plants. The outline includes an overview of plant reproduction, meiosis and alternation of generations, cone and flower structure, seed structure, and fruit structure. The objectives are to discuss plant reproduction, distinguish between cones and seeds, describe seed structure and function, distinguish between meiosis and mitosis, and identify fruit parts and function. Key concepts covered include asexual and sexual reproduction in plants, meiosis, alternation of generations, structures and functions of flowers, cones, seeds and fruits.
Life Cycle and Reproductive Structure
- 1. Chapter 6 Life Cycles &Reproducti ve Structures Presented by: Fasama Hilton Kollie Lecturer, Department of Biology Mother Patern College of Health Sciences
- 2. LESSON OUTLINE 1. Overview of Plant Reproduction 2. Meiosis and Alternation of Generations 3. Cone and Flower Structure 4. Seed Structure 5. Fruit Structure
- 3. LESSON OBJECTIVES By the end of this session, learners will be able to; 1. Discuss reproduction in plant 2. Distinguish between Cones and seeds 3. Describe the structure of a seed and its role in reproduction in plants 4. Distinguish between meiosis and mitosis 5. Identify the parts of a fruit and its role in plant reproduction
- 4. Overview of Plant Reproduction • The capacity of all living things to give rise to new living things of their kind • This includes the transmission of hereditary material from parent/parents to offspring • Life cycle of a species is a sequence of stages leading from the adults of one generation to the adults of the next generation • Life cycle can be either; •Asexual or Sexual
- 5. • Also known as “Vegetative reproduction” • A process in which new organism is produced from a single parent without the involvement of gametes or sex cells • Offspring are genetically identical to the parent • Offspring are often referred to as clones Asexual Reproduction
- 6. • Asexual reproduction is more reliable than sexual reproduction • Plants have two main types of asexual reproduction: 1. Vegetative reproduction 2. Sporulation Asexual Reproduction
- 7. • Also called “Vegetative propagation” • A type of reproduction in which new plants are produced from roots, stems, leaves and buds • Bryophyllum (sprout leaf plant) has buds in the margins of leaves Vegetative Reproduction
- 8. • Vegetative propagation plants takes less time to grow than other plants produce by seeds • There are two types of vegetative reproduction; • Natural vegetative propagation • Artificial vegetative propagation Vegetative Reproduction Cont.
- 9. • A reproductive cell of plants that can develop into an adult without fusing with another reproductive cell • Usually haploid and unicellular and are produced by meiosis in the sporophyte. • Found in seedless vascular plants such as; mosses and ferns Sporulation
- 10. • Sexual reproduction involves two parents • Offspring form are genetically different from both parents and from one another • Sexual reproduction results in new genetic combinations • Offspring produce are genetically variable Sexual Reproduction
- 11. • Three types of reproductive cells are involve in reproduction in plants; •Spores, •Sperms •Eggs • Sperm and egg are referred to as gametes Sexual Reproduction
- 12. • Multicellular organism at some point during their sexual life cycles return to two single cells; sperm and egg. • A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cells • Daughter nuclei produced by meiosis have one copy of each chromosome Meiosis and Alternation of Generation
- 13. • Two types of nuclear division occurs in plants; • Mitosis • Meiosis • Both nuclear divisions have different effects on the number of chromosomes in the daughter cells. • Chromosomes number in a cell vary from species to species MEIOSIS
- 15. • Somatic cell in plants typically contains either one set of chromosomes or two sets of chromosomes • Cells with two sets of chromosomes has homologous chromosomes • Diploid, Haploid • In the Evening primrose, diploid number (2n) is 14 whereas haploid (n) is 7 MEIOSIS Oenothera lamarckiana
- 17. • Meiosis involves two-step division process; • Meiosis I • Meiosis II • Homologous chromosomes separate during meiosis I • Sister chromatids separate during meiosis II • The stages of meiosis are; • Prophase > Metaphase > Anaphase > Telophase and Cytokinesis PMAT-C MEIOSIS
- 18. MEIOSIS - I
- 20. Alternation of Generation • Plant sexual life cycle involves two multicellular forms; • Sporophyte (spore-producing plants) • Gametophyte (Gamete producing plants) • Sporophytes involves diploid cells (2n) and gametophyte haploid cells (n) • Plant life cycle involves alternation of generation
- 22. Alternation of Generation • A typical sexual life cycle of a plant involves five (5) steps; 1. Cells of multicellular diploid sporophyte undergo meiosis to produce haploid spore 2. The spores undergoes mitosis to produce multicellular, haploid gametophyte 3. One or more cells of the gametophyte undergo mitosis to produce haploid sperm or egg 4. Sperm and egg combine in fertilization to produce a diploid zygote 5. The zygote undergoes mitosis to produce a multicellular, diploid sporophyte
- 23. 1 2 3 4 5
- 24. FERN LIFE CYCLE
- 25. Cone and Flower Structure • Cones and flowers of seed plants facilitate sexual reproduction • Both structures have sporophylls with sporangia • Sporangia produces spores which give rise to gametophytes • Pollination precede after gametes formation in seed plants • This is later followed by fertilization
- 26. Sporophyll CONES
- 27. CONES
- 28. Flower Production In Angiosperm • Angiosperms are known for their characteristic flowers that bear enclosed seeds • They develop into Male, Female, or Bisexual flowers • Reproduction is facilitated by pollinators • Color, nectar among others attract pollinators
- 29. Bisexual flowers
- 30. • SEPAL – calyx • PETALS – corolla • STAMENS – androecium • PISTILS - gynoecium Non-reproductive Parts Reproductive parts Typical Flower Component • Reproductive organ of angiosperms • Modified shoot with four whorls
- 31. FLOWER PART FORM AND FUNCTION Peduncle The stalk of a flower Receptacle Part of flower stalk bearing the floral organs at the base of the flower Sepal Leaf-like structures at flower base that protect young flower bud. Often green and leaf-like Calyx All the sepals together form the calyx Petal Located in and above the sepal, often large and colorful, sometimes scented, sometimes producing nectar. Often serve to attract pollinators to the plant Corolla All the petals together form the corolla Stamen Male part of the flower, consisting of the anther and filament, makes pollen grains (male gametes)
- 34. FLOWER PART FORM AND FUNCTION Anther The pollen bearing portion of a stamen Filament Stalk that connect the anther to the base of the flower Pollen Grains containing the male gametes. Immature male gametophyte with a protective outer covering. Carpel/Pistil Female part of the flower. Consisting of the stigma, style and ovary Stigma Often sticky top of carpel, serves as a receptive surface for pollen Style The stalk of a carpel, between the stigma and the ovary, through which the pollen tube grows Ovary Enlarged base of the carpel containing the ova or ovules. The ovary matures to become a fruit Ovule Located in the ovaries. Carries female gametes. Ovules become seeds on fertilization.
- 35. • Flowers can vary in the type of structure present, absent or present of both fertile types of modified leaves and in their symmetry • A flower containing all four modified leaves is said to be Complete • A flower that lacks one or more of these modified leaves is said to be Incomplete Typical Flower Component
- 36. UNISEXUAL FLOWER Typical Flower Component BISEXUAL FLOWER
- 37. Regular/actinomorphic flower (Radial symmetry) Irregular/zygomorphic flower (Bilateral symmetry) Radially symmetrical; divisible into two essentially equal portions along any median longitudinal plane Bilaterally symmetrical; divisible into two equal portion along only one median longitudinal plane Flower Symmetry
- 38. Ovary Position In Flower • Hypogynours: whorls attached below the ovary • Perigynours: stamens and petals adnate to the calyx • Epigynous: whorls attached above the ovary
- 39. Seed Structure • A ripened ovule containing embryo • It is developed in the embryo sac of the ovule in ovary of a flower • Seed formation completes the process of reproduction in seed plants • Gymnosperms and angiosperms produce seeds
- 40. • In gymnosperms, seeds are produce on or near bracts • Angiosperms produce seeds inside the ovaries of flowers • Ovule forms as an attachment to a modified leaf and develops into a seed after fertilization Apple seed inside ovary Bract Seed Structure
- 41. • Maintain dormancy until better environmental conditions arise • Protect developing embryos • Provide nourishment until photosynthesis is possible • Aid in dispersal of plants Seed Function
- 42. • External • Seed coat (testa) • Hilum • Embryo • Cotyledon • Epicotyl • Hypocotyl • Plumule • Radicle Seed Structure
- 43. 1. Absorption of water 2. Cracking of seed coat and growth activation 3. Development of embryonic root 4. Development of embryonic shoot 5. Continuation of normal growth… Steps In Germination
- 45. • A reproductive structure which develops from the ovary and accessory tissue, which surrounds and protects the seed • In flowering plants, seed are enclosed in an ovary • Ovary expand to produce fruit and ovum forms seed Fruit Structure
- 46. • A typical fruit consists of a mature ovary with enclosed seed • Fruits can be either fleshy or dry • The wall of the ovary called the pericarp, consists of three parts; • Exocarp • Mesocarp • Endocarp Fruit Structure
- 48. • Protect the developing embryo from drying out • Protect the embryo from diseases and herbivores • Promote seed distribution by animal that eat the fruit • Provide ready-made fertilizer for the germinating seed Fruit Function
- 49. • Generally, there are three (3) types of fruits; ̶ Simple fruits ̶ Aggregate fruits ̶ Multiple fruits Types of Fruit
- 50. 1. Simple fleshy fruits 2. Simple Dry fruits I. Dehiscent Dry II. Indehiscent Dry Fruits develop from a single ripened ovary (pistil) of a single flower Simple Fruit
- 51. 1. Simple Fleshy Fruits • In simple fruits that are fleshy, one or more layers of the pericarp become soft during ripening • Pericarp fleshy at maturity • The basic types includes: i. Berries ii. Hesperidia iii. Pepos iv. Drupes v. Pomes
- 52. Berries • Fruits having one to many seeds and a pericarp that becomes soft and often sweet and slimy as it matures • Eg: Grapes, Dates, Eggplant, Tomatoes, Green Peppers, Blueberries, Guavas, Banana etc • Fruits similar to berries but with a leathery pericarp that produces fragrant oils • Eg: All citrus fruits such as oranges, lemons, lime, grapefruit Hesperidia
- 53. •Pomes • Bulk of the fruit is formed from a swollen receptacle • Eg; Pears, apples
- 54. Dehiscent Dry: • Dehiscent dry fruits are fruits that open at maturity to shed seeds • The basic types includes; i. Follicles ii. Legumes iii. Siliques iv. Capsules 2. Simple Dry Fruits
- 55. Follicles • Fruits that open along one seam when the seeds are to be released • Eg: Milkweed, columbines, peonies, mangnolia • Fruits split into two seed-bearing halves. Seeds can be born in a common ovary or in separate compartments • Eg: Garden peas, beans, mesquite, peanuts Legumes
- 56. Siliques • Dry fruits in which the seeds reside on a partition between halves of the ovary • Eg: shephers’s purse, cabbage, watercress, radish • Fruits of two or more carpels, split along seams or forming caps or pores • Eg: popples, irises, snapdragons, orchids, yucca Capsules
- 57. Indehiscent Dry: • Indehiscent dry fruits are fruits that remain closed at maturity • The basic types includes; i. Nuts ii. Schizocarps iii. Achenes iv. Samaras v. Caryopses or grains
- 58. Nuts • Dry fruits with hard, thick pericarp and a basal cup • Eg: acorns, hickory nuts, chestnuts, hazelnuts • Have a hard, thin pericarp that splits into two halves. • Eg: carrots Schizocarps
- 59. Achenes • Have thin pericarps. The single seeds connect to the pericarp only at their base • Eg: sunflowers, buttercups • Have a hard, thin pericarp that splits into two halves. • Eg: carrots Samaras
- 60. Caryopses: • Grass seed in which the fruit has a hard pericarp, which is fastened to the embryo all the way around • Eg: All members of the grass family, such as corn and rice Maize Rice
- 61. • Aggregate fruits develops from one flower that has many separate ovary (carpels) • Eg: Blackberries, strawberries, raspberries, magnolias Aggregate Fruit Strawberries Blackberries Raspberries
- 62. • Multiple fruits develops from the pistils of more than one flower • Eg: pineapples, mulberries, figs, breadfruit Multiple Fruit
- 63. Reference • Nabor, Murray W., INTRODUCTION TO BOTANY. Copyright 2004 Pearson Education, Inc., Publilshing as Benjamin Cummings, 1301 Sansome St., San Francisco, CA 94111. www.aw-bc.com
Editor's Notes
- #3: Work on the chapter outline properly
- #5: Reproduction can be describe in terms of life cycles
- #6: The primary form of reproduction for single-celled organisms such as Archaea, Bacteria, and Protists
- #7: Asexual reproduction involves cell division by mitosis Many plants and fungi reproduce mostly asexually ASSIGNMENT #1 Is asexual reproduction more reliable than sexual reproduction List at least five (5) advantages and disadvantages of both sexual and asexual reproduction in a tabular form
- #8: Most plants have roots, stems and leaves. These are called the Vegetative Parts of a plant Bryophyllum (sprout leaf plant) has buds in the margins of leaves If a leaf of this plant fall on a moist soil, each bud can give rise to a new plant
- #9: Plants produced by vegetative propagation take less time to grow and bear flowers and fruits earlier than those produced from seeds ASSIGNMENT #2 List and discuss briefly the types of natural and artificial vegetative propagation
- #10: Organisms use spores as a means of asexual reproduction Spores are usually haploid and unicellular and are produced by meiosis in the sporophyte Bacteria, fungi, algae and some multicellular organism do contain spore
- #11: This form of reproduction is essential for plants that grow in a variety of different environments
- #12: Sexual reproduction involves some risk because egg cells or sperm cells can be damaged or destroyed, thus, hindering reproduction.
- #13: These cells combine to become a zygote that develops into a new multicellular organism A type of nuclear division that is involved only in sexual reproduction and results in daughter cells with half the original number of chromosomes.
- #14: Mitosis produce two daughter nuclei with the same number of chromosomes Meiosis produce four daughter nuclei, each with half the number of chromosomes as the original nucleus.
- #16: In cell with two sets of chromosomes, each pair of chromosomes is called a pair of Homologous chromosomes A cell with two set of chromosomes is said to be diploid (2n) Haploid (n) has a single set of chromosomes In the Evening primrose (Oenothera lamarckiama), diploid number (2n) is 14 whereas haploid (n) is 7
- #18: In plants mitosis can occur in haploid, diploid or polyploid cells Meiosis can only occur within a diploid or polyploid cell with even number of chromosomes
- #21: Plant sexual life cycles are more complex because two multicellular forms of each plant exist. One form is called the sporophyte (spore-producing plants) Consist of diploid cells (2n) The other form is gametophyte (gamete producing plant) Consist of haploid cells (n) ALTERNATION OF GENERATION ?
- #25: In plants, meiosis produce only haploid spores whereas in animals it produces only gametes Plant species vary in the relative sizes of sporophytes and gametophytes and in whether each form can live independently or not In most bryophytes, the gametophyte is larger than the sporophyte In vascular plant, the gametophyte is much smaller than the sporophyte
- #26: Both facilitate sexual reproduction Both form after apical meristems develop into reproductive meristems Both structures have Sporophylls, which are modified spore-producing leaves Sporophylls contain sporangia, hollow structures that produce spores and spores then give rise to gametophytes
- #27: CONE PRODUCTION IN GYMNOSPERMS Gymnosperms are known for their characteristic cones that bear exposed seeds Apical meristems becomes reproductive structures They develop into either Pollen cones or Ovulate cones Pollen cone of pine trees form from meristem that produce a stem with attached leaves The stem becomes the cone axis, whereas the leaves are modified into papery sporophylls containing sporangia
- #29: Apical meristem become reproductive structures They develop into Male, Female, or Bisexual flowers Pollinators facilitate the process of reproduction in flowering plants by transferring pollen grains from males to female parts of flowers Pollinators are attracted to the flowers by colors, nectar, and other attractants
- #33: EDIT THIS FLOWER PROVIDE ANIMATION ALLOWING EACH PART TO BE DISPLAY WHILES YOU DISCUSS IT
- #39: Perigynours: stamens and petals adnate to the calyx, forming a tube (hypanthium) at the base of the ovary
- #40: Seeds facilitate plants’ survival through hard times WHAT IS A SEED? A small embryonic plant enclosed in a coverining called the seed coat, usually with some stored food
- #41: Bracts are exposed leaves found on cones The integument harden to become the seed coat
- #44: GERMINATION STEPS Seed absorbs water under the right atmospheric condition Water cracks the seed coat, activating growth Embryonic root (Radicle) begins to grow downward Embryonic shoot (Plumule) begins to grow upward Normal growth continues… Green leaves begin to develop
- #46: fruit is a reproductive structure of an angiosperm which develops from the ovary and accessory tissue, which surrounds and protects the seed A reproductive structure Angiosperms (flowering plants) Develop from ovary and accessory tissues? Fruit surrounds the seed and protect it
- #47: Fruits primary function is to distribute seeds to new areas where the plants might grow
- #50: The three types are classified according to the arrangement from which they derive Simple fruits develop from a single flower with a single ovary (pistil) Aggregate fruits develops from one flower that has many separate ovary (pistil) Multiple fruits develops from the pistils of more than one flower