Reproduction in Flowering Plants:

Transcription

1 Reproduction in Flowering Plants: ASEXUAL: *DNA is identical to the parent (clones) Plants use this method naturally, they have developed special structures for asexual propagation. *Bulbs, rhizomes, tubers, corms, runners are all structures that can form new plants identical to the parent. SEXUAL: *DNA from male (sperm) and female (egg) is recombined to produce offspring genetically different than the parents. *Flowers developed as the sexual structures in flowering plants. *Egg and sperm come together (egg is fertilized) to produce seeds.

2 Stigma Anther Style Filament Ovary

3 Parts of a flower: Stamen: Male part Anther: produces pollen (sperm) Filament: positions anther Pistil: Female part Stigma: traps pollen (sperm) Style: positions stigma Ovary: produces egg cells, develops into fruit Egg cells: get fertilized by spermdevelops into seeds

4 Lily: unopened bud Poppy:

5 Pollination: Pollen landing on the stigma of a pistil The first step in the development of seed. Reason for Pollination methods: 1. Sperm must travel to the egg (Pistil) of a flower 2. Plants movement is limited 3. Must use other methods to move pollen Methods: Animal Wind Sexual Reproduction:

6 Adaptations for Animal Pollination: 1. Size and Colors of petals: Colors: ie: Red attracts hummingbirds White flowers that open at night- moths Patterns that reflect UV light- patterns to show insects where to land. Patterns that resemble female insects 2. Fragrance Sweet: Attracts animals that like sugar (bees) Rotten: Attracts animals that like rotting meat (flies) 3. Nectar Reward for pollination- sugar water

7 Animal Pollination

8 How some bees see flowers: Regular wavelengths UV patterns

9 This orchid mimics a female wasp. It also releases chemicals that resemble the smell of a female wasp. When male wasps come to mate with this fake female, they pollinate the flowers

10 Adaptations for Wind Pollination: 1. Lack of petals: Energy is not spent on producing petals 2. Lack of Fragrance Energy is not spent on producing these chemicals 3. Lack of Nectar Energy is not spent on producing sugars 4. Lots of pollen: Only by chance that pollen lands on the stigma, produce lots of pollen to increase odds of success 5. Modification of stigma. Large, Feathery, Sticky- all to increase chance of catching pollen.

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13 How would these flowers be pollinated? assavola-martiana.jpg

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15 The next steps in SEX and seed production: 1. Development of nuclei in ovule (egg cell) 2. Formation of the pollen tube. 3. Fertilization Review the female parts of a flower: The pistil Note: the embryo sac is inside the ovule

16 How did the embryo sac get so many nuclei? 2. Egg Cell Preparation for Fertilization Cell division creates multiple nuclei in the ovule (egg cell)

17 Polar nuclei in ovule Egg cell in ovule Pollination: Pollen (orange) lands on the stigma The tube nucleus (green) helps make enzymes that digest a tunnel through the style (yellow).

18 The next steps in seed production: 1. Pollen tube development 2. Development of nuclei in ovule(egg cell) 3. Fertilization 2. Pollen tube development: 1. Development of pollen tube down through the style. 2. Pollen tube is digested by enzymes made by the tube nucleus from the pollen grain. 3. Pollen tube forms all the way to the ovule (egg cell) in the ovary. 4. Sperm nuclei (two of them) follow the tube nucleus down the pollen tube.

19 Tunnel (yellow) forms all the way down to the ovule Tube nucleus (green). Besides the tube nucleus, the pollen grain also has TWO sperm nucleiwhich move down the tunnel to the ovule

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21 The next steps in seed production: 3. Fertilization 1. One sperm fertilizes the egg to form the nucleus 2. The second sperm fertilizes two polar nuclei to form a 3n (triploid) cell.

22 Removed Ovule One sperm cell fuses with the two haploid polar nuclei to form a triploid (3n) cell. (yellow) The other sperm nucleus fuses with the egg cell (green) in the ovule to form a diploid (2n) cell which will grow into the embryo. This cell divides many times to form a tissue called the endosperm. This will be the food for the embryo. The ovule will now develop into a mature seed

23 Parts of the mature seed: Endosperm and cotyledon Seed coat Parts of the Embryo: Epicotyl Radical Review on line sources:

24 From flower to fruit (and seed): How is the flower below pollinated? Two flowers fused together Ovaries swell after fertilization

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26 MONOCOT seed:

27 DICOT seed:

28 Seed Dispersal: Methods to move seeds- why do plants need to move seeds? Methods: 1. Wind: Feathers or wings 2. Water: Air pockets or floats (bladder) 3. Animals: Sticky or burrs Edible fruit 4. Mechanical: Pod explodes- shooting seeds out

29 Overview: Seed Dispersal Methods:

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31 Animals: Hitchhikers

32 Animals: Edibles

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34 Animals: Edibles 20and%20seed%20dispersal%20papers_files/image006.jpg

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36 Mechanical

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38 Water

39 Germination: Seeds break dormancy and begin to grow

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41 Factors that affect Germination: Water: Enough water- too much will block out oxygen and allow rotting pathogens to attack the seed. Temperature: Warm temperatures generally speed up reactions by speeding up molecular motion. Light: Species specific- some need exposure to light. some will not germinate while exposed to light. Scarification: Scaring or cracking the seed coat to allow water to move into the seed.

42 Factors that affect Germination: Stratification: A series of absorbing water followed by exposure low temperature followed by warm temperatures. Fire: Breaks open seed coat allowing water in.