Flowers/Reproduction

Bellringer-April 1, 2014How do flowers reproduce?Do flowers have separate male and female organs? How do flowers pollinate? Provide examples. Flowers/ReproductionHonors Biology

Plant Life CyclePlant life cycles alternate between a sporophyte phase, which produces spores, and a gametophyte stage, which produces gametes. A zygote divides by mitosis and grows into a mature sporophyte, or spore-producing plant.A spore divides by mitosis and grows into a mature gametophyte, or gamete-producing plant.

Flowering Plant ReproductionFlowers are modified leaves, specialized for reproduction (where pollination takes place).Flower parts undergo meiosis to produce haploid productspollen grainovule (contains egg cell)

PollengrainsOvuleFlowerMeiosisMitosisMitosisFlowerSexual reproductive structureProduces egg and spermFertilization takes place inside the flowerReproduces sexually (cross-pollination) and asexually (self-pollination).

6The flower: the defining structure of angiospermsReproductive structure: pollen transfer; specialized shoot with modified leavesSepals: enclose flower before it opensPetals: attract pollinatorsStamens: male sex organs; anther (produces pollen), filamentCarpels (Pistil): female sex organs; stigma, style, ovary, ovules

7 Pistil*Stigma top of the pistil,Sticky surface for pollen to stick to*Style connects the stigma to the ovary*Ovary contains ovules ( eggs)

Stamen*Anther produces sperm nuclei by meiosis. Sperm nuclei are enclosed by pollen grains.*Filament holds the anther up

Female reproductive organ

Male reproductive organ

8Flowers/fruits can be carried by wind, water, or animals to new locations, enhancing seed dispersalFigure 30.9ac

Wings enable maple fruits to be easily carried by the wind.(a)Seeds within berries and other edible fruits are often dispersed in animal feces.(b)The barbs of cockleburs facilitate seed dispersal by allowing the fruits to hitchhike on animals.(c)Pollination

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Pollination: Transfer of mature pollen grains from the anther to the stigma10When a pollen grain lands on the stigma, it germinates and a pollen tube grows down through the style to an ovule (egg)

11FertilizationThe sperm travels through the pollen tube to the ovule. The sperm & egg fuse forming the zygote (fertilized egg) this grows into the plant embryo (cells grow by mitosis)

12*Self pollination pollen from same flower

*Cross pollination pollen from a different flower - more variation

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Pollination is the transfer of pollen from the anther to the stigmaThis is an example of cross-pollination as the pollen travels from one flower to a different flower. This is desirable in plants as it promotes variation.

Flower Structure Pollination Fertilisation Seed Dispersal Germination TestClick to view the animation

14Self-pollination occurs when pollen falls from the anther onto the stigma of the same flowerSelf-pollination is not desirable as it reduces variationClick to show animation of self-pollination

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test15Flowers will prevent self-pollination by either having stigma above stamen orFlower Structure Pollination Fertilisation Seed Dispersal Germination Test16by having stamen and stigma mature at different times.

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test17The ovary and zygote (fertilized ovule) develop and ripen.*The ovule forms the seed and the ovary forms the fruit.Seed = embryo + stored food + seed coatFruit = ovary wall, mechanism for seed dispersal A fruit is a ripened ovary

18FruitsForm when ovary with ovules (eggs) ripensMay be dry and hardened (nuts)May be enlarged and fleshy (berries, apples, tomatoes) TASTY!!!Used to help disperse seeds

Flowers, Fruits, and vegetablesA fruit is the part of the plant that develops from a flower. It's also the section of the plant that contains the seeds. (Protects the seeds).

The other parts of plants are considered vegetables. These include the stems, leaves and roots and even the flower bud.

Dead Center sits the tomato. Why?Dead Center sits the tomato. Why?

Botanically speaking, a tomato is a fruit because it is a seed-bearing structure that develops from the ovary of a flowering plant.

In the culinary world sweet = fruits and savory = vegetables: this includes botanical fruits as eggplants, bell peppers, and tomatoes.