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Schenk
Pollination
10
Plant Sciences
Undergraduate 2
11/02/2016

Additional Plant Sciences Flashcards

 


 

Cards

Term
What are pollen sacs called?  What do they contain?
Definition

Sporangia (sing. = sporangium)

Contain numerous diploid cells (microsporocytes)

Term
What happens to microsporocytes?  What do their products contain?
Definition
Undergo meiosis to produce 2 cells, each is a gametophyte containing a generative cell and a tube cell
Term
How many megaspores does the megasporocyte produce after meiosis?
Definition
4 (n)
Term
How many megaspores generally survive per tetrad in angiosperms?
Definition
1
Term
How many haploid nuclei are in the female gametophyte after meiosis and mitosis?
Definition
8
Term
When does pollination occur?  When does fertilisation occur?
Definition

When pollen lands on the stigma of the carpel.

When the haploid male and female gametes fuse to form a diploid

Term
What triggers the growth of the pollen tube towards the micropyle?
Definition
Chemical recognition of mates/pollen rehydration
Term
Where to the male gametophyte nuclei fuse in fertilisation?
Definition

One fuses with egg cell to produce the zygote (2n)

Other binds with two polar nuclei to produce endosperm (3n), food storing tissue

Term
What mechanisms have plants evolved to inhibit self fertilisation?
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)

Term
What are the pros and cons of outbreeding vs inbreeding?
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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