reproduction in plants lecture five.ppt
- 1. UNIVERSITY OF BUROA course: pastoral botany veterinary semester one lecture: reproduction in plants (lecture five) lecturer: Dr Salah Qasim
- 2. Lecture objectives Student should able to know Diference between sexual and a sexual reproduction in plants A sexual reproduction methods Life cycle of both a sexual and sexual reproduction in plants Pollination and pollinators Seed germination and seed dispersion
- 6. Vegitative Reproduction A form of asexual reproduction where a new plant grows from parts of an existing plant. Fast reproduction Examples: Strawberry runners Moss fragmentation Potato eyes and buds
- 11. • Sexual reproduction –Joining of an egg and sperm • Asexual reproduction –A single organism replicating its genetic material to split into two identical organisms.
- 12. • Sexual reproduction takes place with slight variations in different groups of plants. Plants have two distinct stages in their life cycle: the gametophyte stage and the sporophyte stage. • The haploid gametophyte produces the male and female gametes by mitosis indistinct multicellular structures. Fusion of the male and females gametes forms the diploid zygote, which develops into the sporophyte.
- 13. Asexual Reproduction • Many plants are able to propagate themselves using asexual reproduction. • This method does not require the investment required to produce a flower, attract pollinators, or find a means of seed dispersal.
- 14. Asexual reproduction produces plants that are genetically identical to the parent plant because no mixing of male and female gametes takes place. Traditionally, these plants survive well under stable environmental conditions when compared with plants produced from sexual reproduction.
- 15. Sexual vs Asexual Asexual Reproduction – involves only 1 parent – offspring genetically identical to parent – involves regular body cells – its quick Sexual Reproduction – involves 2 parents – offspring genetic mix of both parents – involves specialized sex cells – its slow
- 16. Which is Better? It depends! Asexual Reproduction advantages – does not require special cells or a lot of energy – can produce offspring quickly – in a stable environment creates large, thriving population disadvantages – limited ability to adapt – face massive die-off if environment changes Sexual Reproduction advantages – lots of variation within a species – able to live in a variety of environmental settings – able to adapt to changes in the environment disadvantages – needs time & energy – produce small populations
- 18. Alteration of Generations Of Naked Seed Vascular Plants
- 19. Alteration of Generations Fertilization: • Nonvascular plants- Need a film of water for the sperm to reach the egg. • Vascular plants- Do not need water for the sperm to reach the egg.
- 20. Alteration of Generations As plants evolved, the sporophyte generation became larger: • Nonvascular plants- Sporophyte depends on the gametophyte for support and nutrition • Vascular plants- Sporophyte lives independent of the gametophyte.
- 21. Moss reproductive cycle • Antheridium- Male produces flagellated sperm that need water to get to the archegonium. • Chemotaxis- Female archegonium produces chemicals that attract/direct the sperm.
- 22. Alteration of Generations Of Nonseed Nonvascular Plants
- 23. Fern reproductive cycle • Sporophyte dominant • Frond- feathery stems of a fern • Sorus- underneath the frond –Produces spores
- 24. Fern reproductive cycle • Prothallus –The fern spore grows into a prothallus when it lands on damp, rich soil. –Heart shaped –Contains Antheridia & Archegonium
- 26. Conifer reproductive cycle • Sporophyte dominant • Heterosporous- Produces two kinds of spores that develop into male and female cones. – Female cones –Made of many scales –2 ovules at the base of each scale –Each ovule produces a Megaspore which develops into the female archegonia.
- 27. Conifer reproductive cycle – Male cones –Made of small scales that form microspores –4 microspores develop into a single pollen grain –Pollen grains are the male gametophyte that are transported on air currents
- 28. Sexual reproduction in plants • Most flowers have four parts: • sepals, • petals, • stamens, • Carpels (pistils)
- 29. The parts of a flower • Sepals protect the bud until it opens. • Petals attract insects. • Stamens make pollen. • Pistils (carpel) grow into fruits which contain the seeds.
- 31. Stamen (male) • Anther: pollen grains grow in the anther. • When the grains are fully grown, the anther splits open. • Filament: holds the anther
- 32. Pistil (female) • Stigma • Style • Ovary Stigma – sticky place for pollen to attach Style – where pollen nuclei travels to reach the egg Ovary – where egg is located
- 33. Sexual Reproduction in Plants (Pistil) Male Parts Female Parts pollen (male) + ovule (female) → single-celled zygote → multi-celled embryo (contained in a seed) → new individual
- 34. Sexual Reproduction Summary Male Gamet e Female Gamete Type of Union Result of Union Final Result Plants pollen ovule (egg) pollination single cell zygote multi-cell embryo (in seed) Animals sperm egg fertilization single cell zygote multi-cell embryo
- 35. Modifications in Flowers • Complete flowers – have all four organs (sepals, petals, stamens, and pistils) • Incomplete flowers – lacks one or more of the four organs
- 36. Tiger Lily – a complete flower
- 37. Female Squash Flower Male Squash Flower Incomplete Flowers
- 39. Pollination Mechanisms • Animal pollination – birds & bees transfer pollen from plant to plant – Flowers are brightly colored or highly scented • Wind pollination – lightweight and are carried by wind – Small flowers with little color or scent • Self pollination – Able to pollinate flowers on same plant – Have both pistel and stamen
- 41. Pollinators
- 42. Alteration of Generations Of Flowering Seed Vascular Plants
- 45. Seed Dispersal • Water – Coconuts • Wind – Dandelions • Animals – Fruits attract animals that will eat the seeds so that the seeds can be carried far away where it won’t have to compete with its parent.
- 47. Seed Germination • the process of a seed starting to grow, or the act of causing a seed to start growing Requires: – Water (swells and breaks seed coat) – Oxygen (cell respiration as seed grows) – Optimal Temperature (each plant requires a certain temperature to begin growth) Seeds will lie dormant in their hard seed coats waiting for optimal conditions.