Plant Reproduction Flashcards
(29 cards)
Speals
Protect flowering bud
Petals
Attract insects for pollination
Stames
Produce more pollen
Carpels
Produce female embryo sac
Pollen development
Diploid(2n) micros pore mother cells divide by meiosis to form 4 haploid cells
Each haploid forms a pollen grain
Nucleus of the pollen grain divides by mitosis to form a tube nucleus and a generative nucleus
Embryo sac development
Single diploid megaspore mother cell divides by meiosis to form 4 haploid cells
3 degenerate and 1 divides by mitosis 3 times
Cell with its nuclei is known as the embryo sac
Pollination
Transfer of pollen grain from an anther to a stigma of a flower of the same species
Types of pollination
Self pollination: uses its own pollen
Cross pollination:uses pollen from another plant (insect/animal and wind)
Fertilisation
The fusion of two haploid gametes to form a diploid zygote
Stages of fertilisation
Pollen grain germinates and the generative nucleus divides by mitosis to produce 2 male gamete nuclei
Tube nucleus grows down through the style (chemotropism)
2 male gamete nuclei enter the embryo sac and double fertilisation occurs:
-1st male gamete+female egg=zygote
-2nd male gamete+2 polar nuclei=triploid endospermic nucleus
Seed formation
Fertilised ovule becomes the seed
Food stores
Cotyledon
Endosperm
Fate of zygote after fertilisation
Develops to form embryo
Fate of endosperm nucleus after fertilisation
Develops to form endosperm food store
Fruits are formed from
Ovary
Methods of seed dispersal
Wind
Animal
Water
Self
Germination
Regrow the of the embryo after a period of dormancy, if conditions are suitable
Conditions necessary for germination
Water
Air
Suitable temperature
Process of germination
Seed absorbs water
Enzymes digest the food stores ie. Starch is turned to glucose
Radicle grows and bursts through the testa
Plumule emerges above ground
Stem and leaves develop
Dormancy
Resting period where seeds undergo no growth and have reduced metabolic activity
Advantages of dormancy
Allows plants to avoid the harsh conditions of winter
Gives embryo time to fully develop
Allows maximum growing time
Vegetative propagation
Asexual reproduction in flowering plants
Natural vegetative propagation
Stem-potato
Root-raspberry
Bud:onion
Artificial vegetative propagation
Cutting
Layering
