plant reproduction Flashcards
(34 cards)
What are the features of insect-pollinated flowers?
Anther and filament inside flower so insects brush against them; sticky carpel collects pollen from insect bodies.
What are the features of wind-pollinated flowers?
Large anther hangs outside with small petals; large feathery carpel hangs outside to catch airborne pollen.
What is cross-pollination?
Pollen from one plant is transferred to the stigma of a different plant of the same species.
What are the advantages of cross-pollination?
More variation from meiosis, mutation, and mixing of genes; better survival in changing environments.
What is self-pollination?
Pollen from a plant is transferred to the stigma of the same plant.
What are the advantages of self-pollination?
Good for stable environments; less variation but successful traits retained.
How do plants prevent self-pollination?
Chemical incompatibility, irregular flower structure, or different ripening times.
Where do pollen grains develop?
In the anthers.
How are pollen grains formed?
Pollen mother cells undergo mitosis then meiosis to form a tetrad of 4 haploid cells.
What happens inside each haploid pollen grain?
Mitosis forms a generative nucleus and a tube nucleus.
What is the function of the tapetum?
Provides nutrients to developing pollen grains.
What causes dehiscence in anthers?
Tension from drying causes the pollen sacs to split open.
Where do ovules develop?
In the ovary.
How is the embryo sac formed in ovules?
A megaspore mother cell undergoes meiosis to form 4 haploid nuclei; 1 survives and divides mitotically to form 8 cells.
What are the 8 cells in the embryo sac?
3 antipodal cells, 2 polar nuclei, 1 ovule, 2 synergids.
How does fertilisation begin?
Pollen grain on stigma forms a pollen tube towards the micropyle.
What controls pollen tube growth?
The tube nucleus.
What guides the pollen tube?
Negative aerotropism and positive chemotropism.
What happens during double fertilisation?
One male gamete fuses with egg to form diploid zygote; other fuses with polar nuclei to form triploid endosperm.
What does the ovule become after fertilisation?
A seed.
What does the ovary become after fertilisation?
The fruit wall (pericarp).
What does the diploid zygote develop into?
The embryo (plumule, radicle, cotyledons).
What does the triploid endosperm become?
Endosperm tissue for food storage.
What do the integuments become?
The testa (seed coat).
