Term
| What are pollen sacs called? What do they contain? |
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Definition
Sporangia (sing. = sporangium)
Contain numerous diploid cells (microsporocytes) |
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Term
| What happens to microsporocytes? What do their products contain? |
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Definition
| Undergo meiosis to produce 2 cells, each is a gametophyte containing a generative cell and a tube cell |
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Term
| How many megaspores does the megasporocyte produce after meiosis? |
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Definition
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Term
| How many megaspores generally survive per tetrad in angiosperms? |
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Definition
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Term
| How many haploid nuclei are in the female gametophyte after meiosis and mitosis? |
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Definition
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Term
| When does pollination occur? When does fertilisation occur? |
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Definition
When pollen lands on the stigma of the carpel.
When the haploid male and female gametes fuse to form a diploid |
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Term
| What triggers the growth of the pollen tube towards the micropyle? |
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Definition
| Chemical recognition of mates/pollen rehydration |
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Term
| Where to the male gametophyte nuclei fuse in fertilisation? |
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Definition
One fuses with egg cell to produce the zygote (2n)
Other binds with two polar nuclei to produce endosperm (3n), food storing tissue |
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Term
| What mechanisms have plants evolved to inhibit self fertilisation? |
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Definition
Temporal separation: Active at different times
Self incompatibility systems: rejection of self based on S-genes (if S allele same in pollen and stigma then no pollen tube growth), gametophytic (RNA in developing pollen tube degraded) and sporophytic (activated pathway in stigma cells inhibits pollen germination) |
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Term
| What are the pros and cons of outbreeding vs inbreeding? |
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Definition
Outbreeding: maintain genetic diversity, adaptable to changes in environment, endangered when isolated, dependence on pollinator
Inbreeding: maintain specific genotype, fast repliation, less adaptable to changes in environment |
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