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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 Seeds have one or more cotyledons that store or help absorb food for the sporophyte. 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. Gametophyte generation—maple pollen Sporophyte generation—maple tree

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 Reproduction in Gymnosperms
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

7 Reproduction in Gymnosperms

8 Reproduction in Angiosperms
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

9 Reproduction in Angiosperms

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

11 Germination

12 Structure of a Flower 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

13 Structure of a Flower

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 Plant Responses 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

17 Plant Responses

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