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