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Plant Reproduction & Response to the Environment.

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Presentation on theme: "Plant Reproduction & Response to the Environment."— Presentation transcript:

1 Plant Reproduction & Response to the Environment

2 Seeds  A plant structure that contains an embryo, contains nutrients for the embryo, and is covered with a protective coat  These features enable seeds to survive harsh environmental conditions and then sprout when favorable conditions exist.

3 Seeds have one or more cotyledons that store or help absorb food for the sporophyte. Seeds Plants whose seeds are part of fruits are called angiosperms (flowing plants) Plants whose seeds are not part of fruits are called gymnosperms (non-flowering plants)

4 Alternation of Generations  Gametophyte (haploid)generation produces gametes.  Sporophyte (diploid)generation produces spores that can grow to form the next gametophyte generation. Sporophyte generation—maple tree Gametophyte generation—maple pollen

5 Alternation of Generations Diploid sporophyte generation alternates with a haploid gametophyte generation Gametophyte of gymnosperms are in the cones, and in angiosperms they are in the flowers

6 Two types of cones: – Pollen cone (male cone) – produce pollen – Seed cone (female cone) – contains the ovules, where the eggs are held Pollination – transfer of pollen from the male structure to the female structure Fertilization and development then occur Reproduction in Gymnosperms

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8 Occurs in the flower Most angiosperms are pollinated by animals (insects, birds) Double fertilization – One sperm fertilizes the egg and becomes the zygote – A second sperm fertilizes the embryo sac and becomes the food supply Reproduction in Angiosperms

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10 The ovary becomes the fruit Seeds are dispersed by animals, wind, and water Germination – early growth of the plant

11 Germination

12 Sepals – enclose the bud Petals – attract pollinators Stamen – male structure – Filament – long, thin stalk that supports the anther – Anther – produces pollen Carpels (or pistils) – female structure – Ovary – contains the ovules – Style – stalk of the carpel – Stigma – sticky surface where pollen lands Structure of a Flower

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14 Asexual Reproduction Vegetative reproduction – production of new plants from stems, leafs, and roots Cutting – pieces of plant cut off and planted Grafting & budding – a stem or bud is cut from one plant & attached to another

15 Plant Hormones Auxins – stimulate cell elongation Cytokinins – stimulate cell division Gibberellins – produce increases in size Ethylene – stimulates fruit to ripen

16 Tropisms – responses of plants to environmental stimuli – Gravitropism – response to gravity – Phototropism – response to light – Thigmotropism – response to touch Positive – in the direction of the stimulus Negative – away from the stimulus Plant Responses

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