A single flowering plant produces pollen with a mutation that causes the pollen tubes to grow to only half their normal length. What will be the most likely long-term effect of this mutation on the local population of this type of plant?

Plants produced from eggs fertilized by this pollen will only grow half as tall as the others, resulting in a population with short and tall plants.

Since the pollen tubes cannot grow long enough to reach the eggs, the mutation will not be passed on and will not affect the plant population.

The pollen tubes will reach the eggs sooner, which will result in seeds from this pollen being produced faster, making the mutation more likely to get passed on.

Within a few generations the mutation will have spread through the population, making all the pollen tubes shorter.

Question

A single flowering plant produces pollen with a mutation that causes the pollen tubes to grow to only half their normal length. What will be the most likely long-term effect of this mutation on the local population of this type of plant?

Plants produced from eggs fertilized by this pollen will only grow half as tall as the others, resulting in a population with short and tall plants.
		
Since the pollen tubes cannot grow long enough to reach the eggs, the mutation will not be passed on and will not affect the plant population.
		
The pollen tubes will reach the eggs sooner, which will result in seeds from this pollen being produced faster, making the mutation more likely to get passed on.
		
Within a few generations the mutation will have spread through the population, making all the pollen tubes shorter.

blues · Answer

You should use process of elimination - do any of these strike you as being wrong or right. Or you should give us some indication of what part of the question you don't understand and would like help with. :D

anonymous · Answer

I'm pretty sure it's not A. But would it make the pollen tubes too short if it was half the size? I don't really know how long the pollen tube needs to be.

blues · Answer

I agree with you that it is not A.

And it is probably not D either, although you don't know enough about the way the gene expresses itself to rule it out entirely. If the trait were incompletely dominant, the heterozygotes (of which there would be many after a few generations) would have pollen tubes of intermediate length - but would *all* plants have shorter tubes? Probably not. For that reason I think D is out as well.

Do you like or not like either of remaining two more than the other?

anonymous · Answer

I'm kinda leaning towards B because C sounds a little illogical to me.

blues · Answer

I am leaning toward B also.

It does not give you any info about whether short tubes are too short. But C has to do not with tube length but with frequency of pollination which is the same, regardless of tube length. So it seems illogical to me, too.

anonymous · Answer

Thank you for your help!

blues · Answer

Not a prob. Thanks for your patience in working through the problem!