Need help with on a Bio Question.

[InternationalPreDen]

A pair of chromosomes that contain gene at the same loci, have the same length, and have the same centromere positions are referred to as

A. alleles
B. sister chromosomes
C. sister chromatids
D.homologous chromosomes
E.Autosomes

The correct anser is D. However, I think C. sister chromatids is a valid answer as well. Can someone explain this to me please? Thank you very much!

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[deleted696582]

The question says "A pair of chromosomes...". Sister chromatids aren't chromosomes by definition.

So yeah, sister chromatids kind of fit that criteria, but they still aren't chromosomes. They can't have "the same centromere positions" because they are just connected by one centromere.

 

[510586]

The question says "A pair of chromosomes...". Sister chromatids aren't chromosomes by definition.

So yeah, sister chromatids kind of fit that criteria, but they still aren't chromosomes. They can't have "the same centromere positions" because they are just connected by one centromere.

They define sister chromatids as chromosomes when they separate

 

[Ahmadtoo]

They define sister chromatids as chromosomes when they separate

But it says they share the same centromere positions...

If they split and have 2 separate centromeres, that's when you can define sister chromatids as chromosomes, so be careful with that. Cliff's suggest that you count chromosomes based on the number of centromeres.

So since they say a pair of chromosomes that share the same centromere positions, the answer is D. Homologous Chromosomes.

 

[510586]

But it says they share the same centromere positions...

If they split and have 2 separate centromeres, that's when you can define sister chromatids as chromosomes, so be careful with that. Cliff's suggest that you count chromosomes based on the number of centromeres.

So since they say a pair of chromosomes that share the same centromere positions, the answer is D. Homologous Chromosomes.

I would put D in this case to be safe, but centromere position could mean where the centromeres are located on the chromatids as well right? You can have centromeres in the same position after splitting too.

 

[Ahmadtoo]

I would put D in this case to be safe, but centromere position could mean where the centromeres are located on the chromatids as well right? You can have centromeres in the same position after splitting too.

I see what you're saying, but I feel like the question asks about sharing the centromere in a more direct meaning.

 

[510586]

Sorry I just reread your second paragraph and I'm 100% sure your explanation is correct. If they split, they are called chromosomes not sister chromatids.

I see what you're saying, but I feel like the question asks about sharing the centromere in a more direct meaning.

 

[InternationalPreDen]

But it says they share the same centromere positions...

If they split and have 2 separate centromeres, that's when you can define sister chromatids as chromosomes, so be careful with that. Cliff's suggest that you count chromosomes based on the number of centromeres.

So since they say a pair of chromosomes that share the same centromere positions, the answer is D. Homologous Chromosomes.

I think homologous chromosomes do not share the same centromere position since each homologue has its own centromere.

 

[InternationalPreDen]

This question is from Crack the DAT Bio Test 2 Question 34, and the video explanation for this question states that " Sister Chromosomes are separated Sister Chromatids, so Choice B and Choice C are essentially the same thing. Hence, the correct choice is D." In addition, the lady in the video kept explaining that how 2 Sister Chromatids of the same chromosome are identical, and how homologous chromosomes are not.. This is very confusing.

 

[BYU4you]

This question is from Crack the DAT Bio Test 2 Question 34, and the video explanation for this question states that " Sister Chromosomes are separated Sister Chromatids, so Choice B and Choice C are essentially the same thing. Hence, the correct choice is D." In addition, the lady in the video kept explaining that how 2 Sister Chromatids of the same chromosome are identical, and how homologous chromosomes are not.. This is very confusing.

The question never states they are identical. It says a pair of chromosomes with same genes at same loci.

This question is pretty straight forward to me. Sister chromosomes isn't even a term you will come across elsewhere except wrong answers.

Edit: let me rephrase my last sentence for clarity.

Homologous chromosomes both have identical centromere position hence they share the same centromere. To me this question is really about the first part that says a pair of chromosomes. While sister chromatids could fit this description later, it's safe to assume they are talking about during metaphase since that is the time when you actually visualize chromosomes and during metaphase this description photos homologous chromosomes better.


And this is a type of question you could see on the real dat even though it is not really clear. That's just the name of the game.