February 10, 2012 at 8:00 am #16066
1. Winter wheat can be planted in the spring for fall harvest if it is
a. sprayed with gibberellins.
b. soaked in water.
d. planted under a full moon.
d. stored in the dark for 50 days.
Answer said it was E. but can’t A also be right?
2. For plants that flower in response to photoperiodic stimuli, the most critical determinant in the light–dark cycle is the
b. length of the dark period for short-day plants and length of the light period for long-day plants.
c. length of the light period for short-day plants and length of the dark period for long-day plants.
d. length of the uninterrupted dark cycle.
e. length of the uninterrupted light cycle.
I read in my book that the period of darkness is what matters. So shouldn’t the answer be D?
3. The three nuclei in a mature pollen grain are formed by
a. one meiotic division and one mitotic division.
b. two meiotic divisions and one mitotic division.
c. one meiotic division and two mitotic divisions.
d. two meiotic divisions and two mitotic divisions.
e. one meiotic division in which one of the four cells degenerates.
I’m not sure if this question is right……doesn’t a mature pollen grain only have 2 nuclei? The generative and tube cell?
4. As a pollen tube grows into the female organ, the nucleus that enters the synergid first is called the
a. sperm nucleus.
b. generative nucleus.
c. tube nucleus.
d. pollen nucleus.
Answer says C. but I’m pretty sure it’s A. Can anyone confirm?
a. is of little importance to agriculture.
b. refers to the requirement of the seeds of some plants for exposure to winter temperatures before they germinate.
c. refers to the requirement of some biennial plants to be exposed to winter’s cold temperatures before they flower the next spring.
d. refers to the induction of cold hardiness of buds.
e. Both b and c
Answers key says E. but doesn’t vernalization only have to do with flowering? If so shouldn’t it then just be C?
February 10, 2012 at 8:54 am #109568JackBeanParticipant
1. not really, the plant needs to be at cold temperature, so only GA signal is not sufficient
2. seems OK to me
Do not confuse cell and nucleus!
4. there’s nothing like sperm nucleus
5. Obviously notquote [url=http://en.wikipedia.org/wiki/Vernalization:
You didn’t really try hard, did you?
February 10, 2012 at 9:25 am #109569quote JackBean:
1. But doesn’t GA promote seed germination and flowering?
2. can you elaborate? why would why the length of light be the critical factor for LDP when experiments have shown that having a critical dark period was what mattered.
3. ok but isn’t the pollen tube derived from the mature pollen grain which has 2 cells hence 2 nuclues? (didn’t get it confused btw)
4. HUH??? are you saying there’s no sperm nucleus?
February 10, 2012 at 10:11 am #109570JackBeanParticipant
2. I agreed with you, so why are you so asking?
4. in accordance to wiki not (see above)
February 10, 2012 at 10:56 am #109572quote JackBean:
2. lol sorry bout that…half asleep when i read it
3. wiki isn’t always reliable. I was looking through textbooks and only saw the generative and tube cells as the pollen grain. But maybe i’m missing something.
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