2 Types of reproductionAsexual – the production of clones; no other plant necessary Sexual – gametophytes formed; pollination is necessary
3 Asexual reproduction Also called vegetative reproduction Asexual reproduction occurs in various ways:- production of rhizomes (modified stems);could be ‘eyes’ on potatoes- from fragments of roots or shoots (e.g dandelions, quack grass
4 Costs and benefits Benefits? Advantageous traits will be passed on Less energy than sexual reproductionFasterOnly one plant neededYoung plantelets are more robust and survive better
5 One big cost…..No diversity in genetic clones – if the environment changes quickly or if there is a disease or insect outbreak, the entire population will die….
6 Human uses of asexual plant reproduction Gardeners, nurseries Reproducing copies of plants with desirable characteristics using methods such as:Stem cutting – in water or soil where new roots will formGrafting - branch from plant with desirable features is attached to stem of other plant (commonin orchards)Tissue culture – piece of plant in test tubewith growth media
7 Sexual reproductionThe product of sexual reproduction is a seed. Seed function: - to protect and nourish the embryo - to move the embryo to a new location
8 Costs and benefits Benefits: High level of genetic diversity Seeds are dispersed; less competition for resourcesSeeds can remains dormant for a long timeCost?- Lots of energy – specialized structures
9 Sexual reproduction Similar in angiosperms and gymnosperms Meiosis forms gametophytes – pollen grain and ovulePollen grain is carried to ovule (in the process of pollination) where fertilization occursEmbryo grows by mitosisGermination occurs
10 From Pollen to Ovary The pollen grain grows a pollen tube towards the ovary, which contains the ovule and egg cell (female gamete).pollen tubeovary containing ovule10
11 9AdFertilizationFertilisation takes place when the ‘sperm’ nucleus from the pollen grain enters the egg cell. The resulting zygote eventually turns into a seed.pollen tube with pollen grain nucleusovuleEmbryo grows inside the ovule.egg cell11
12 Zygote to EmbryoThe zygote will grow through the process of mitosis to form an embryo (The ovule is now called a seed and is covered by a protective seed coat.)seedseed coatfood supply(cotyledon)embryo
13 Fruit Formation Some plants produce fruit containing seeds. Fruit: Mature ovaryTissue surrounding the embryo develops into fruit.When the fruit is fully developed it drops off the plant, or is carried away by an animal.When fruit decomposes it releases the seed and germination can occur.
14 Germination A seed requires moisture (water) to germinate. The as the embryo grows, the root and shoot break through the seed coat.Nutrients stored in the cotyledon provide nourishment and support early development
15 Sexual reproduction in gymnosperms Conifers (e.g pines and cedars) produce both male and female cones Male gametophytes (haploid) produced and stored in pollen grain Wind pollination gets pollen grain to female gametophyte (haploid) in ovule One sperm nuclei fertilizes the egg after a pollen tube grows into ovule (13 months)
17 Sexual reproduction in angiosperms Seeds are contained inside a fruit – a mature ovary This fruit is an important part of the diet for many animals including humans. Sexual structure is the flower…….
19 Reproductive Parts Male reproductive organs (stamen): Anther: produces pollen grainsFilament: supports anther above female reproductive organsFemale reproductive organs (carpel):Stigma: sticky landing site for pollen grainsStyle: tube that leads down to ovaryOvary: contains ovules that develop into seeds
20 Reproductive Mechanisms Pollen (male gamete) from one plant landson the stigma of another plant.This is called pollination.pollenstigma20
21 Monocot and dicot flowers Monocot: Petals and stamens are always in multiples of three. Dicot: Petals and stamens are in multiples of four or five.
22 Pollination and fertilization in angiosperms Cross – pollination: by wind or animals between flowers of different plants of the same or closely related species(pollinators) – like? Self-pollination: pollen transfer from flowers on the same plant
25 Selective breeding in plants 9AdSelective breeding in plantstexturesizeSelective breeding and cross-breeding are carried out on plants to produce flowers and crops with desirable characteristics…tastecolour25
26 9A Plant-breeding techniques Anne the plant breeder chooses two parent plants with useful characteristics.One plant will be the female parent. Anne removes the anthers and covers the flower with a bag. Why?female parentThe other plant is the male parent. Its anthers develop as normal.Anne collects its pollen and brushes it onto the female plant.collected pollenanthers removedShe puts the bag over the flower again. Later she collects the seeds and grows them to produce the new plant.
27 Fruit formationA fruit – a mature ovary that helps protect and disperse the seed Fruit – can be sweet and fleshy (e.g. plums and strawberries) or dry like walnuts and wheat or vegetables (e.g. peppers, peas and squash)
28 Importance of seedsGrain crops (like wheat) are staples around the world Greenhouses Seed collection for breeding Survival of other species on earth
29 Comparing Plant and Human Reproductive Systems Male and Female organsMale Gamete is pollenFemale Gamete is egg produced in ovulePollen nuclei fuses with egg nuclei (fertiliation)Diploid zygoteZygote grows into embryoEmbryo grows inside protective seed coatCotyledons provide nourishmentMale or Female organsMale Gamete is spermFemale Gamete is egg produced in ovarySperm nuclei fuses with egg nuclei (fertilization)Diploid zygoteZygote grows into embryoEmbryo grows inside protective wombPlacenta provides nourishment