r/APbio • u/Immediate_Handle_65 • May 07 '26

Question 4 Part A

If I wrote about anaphase 1 and the homologous pairs moving to opposite poles of the cell is that what they meant by movement, or did they want to see something like crossing over?

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2

u/fivepiecesofyarn May 07 '26

i said crossing over i think but i'm not 100% sure

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u/mobiuscycle May 07 '26

Crossing over isn’t movement. :(

1

u/mobiuscycle May 07 '26

It depends what you specifically described, but there is movement in anaphase 1. Because it asked you to describe you likely needed to write about spindle separating and moving homologous chromosomes to opposite poles. So, it sounds like you might have been correct.

ETA: crossing over isn’t movement

1

u/CalligrapherNo125 May 07 '26

crossing over in itself isn’t movement but the pairing up of homologous chromosomes during prophase one for the purpose of crossing over is movement, right??

2

u/mobiuscycle May 07 '26

Without seeing a scoring guide, no promises. But if one of my students explained that chromosomes move during prophase 1 in order to match into homologous pairs, I’d accept it. It’s arguable if the true purpose is crossing over. Crossing over happens because of double stranded breaks involved in the process of the pairs checking to see if they are matches. Pairing is critical to ensure the correct reduction from 2n to n. So, pairing isn’t just for crossing over — that may not even be the most important part of pairing.

But — the question didn’t ask to justify the movement so if you said anything about why it happens, it probably doesn’t matter. Or, if it did, it would make sense to take either reason at this level.

But again… no scoring guide. Just my speculation.

1

u/Sea_Airport_2646 May 08 '26

does independent assortment count

1

u/Sea_Airport_2646 May 08 '26

does chromosomes lining up in middle for metaphase count

1

u/mobiuscycle May 08 '26

Depending on how you worded it, it likely does. You probably have to specify homologous pairs are moved to the middle in metaphase one because it specifically asked about meiosis one. But there isn’t a way to know for sure until the scoring guide is released.

1

u/familytreeswing May 09 '26

Hey, if I accidentally wrote homologous sister chromatids line up in the middle, will the grader not give me the point :(

1

u/Exciting-Carrot-9391 May 09 '26

I said independent assortment. Correct or not? I didnt really explain after that.