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.

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

21. 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

44. Seed Germination
DICOT MONOCOT

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