Chromosome questions

could somebody be a darling and tell me how to answer these two questions please :biggrin:

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Study help works best if you have a go at the question first and post your attempt so we have something to work with - we’re happy to help you once you’ve made an effort at answering it yourself. It is not designed for dumping questions and expecting someone to complete your homework for you.

Reply 2

asdfgghjkl

Original post by Reality Check

lol its not homework, im an external candidate whos completed his a levels just retaking a unit from biology. I've attempted to answer it but i cant. I dont have a tutor i can go to, so student room was my best bet. im not "dumping" anything on here.

Reply 3

asdfgghjkl

Original post by Reality Check

have a go at the question first and post your attempt so we have something to work with .

the first part i would of drawn this, Mark scheme makes it hard to understand if its correct.

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Reply 4

CTLeafez

Original post by Ismail786

could somebody be a darling and tell me how to answer these two questions please :biggrin:

The provided diagram shows a cell which is diploid. That means you have 2 versions of each chromosome. Cells go through meiosis to create haploid gametes (sex cells). Haploid means you have half the number of chromosomes within the cell (only one version of each). Use that information to figure out what would be the contents of the cell you need to draw :smile:

Reply 5

asdfgghjkl

Original post by CTLevers

im still clueless for part 5dii...

Reply 6

CTLeafez

Original post by Ismail786

im still clueless for part 5dii...

The question is asking how many types of gametes can be created from paternal (father - XY) and maternal (mother - XX) so I would say the answer would be two.

XX, XY are the only combinations possible. Egg cells only ever possess X chromosomes, while sperm can possess X or Y.

Reply 7

username2396569

Original post by CTLevers

surely it'll be 2^3, it's asking how many different combinations of the chromosomes you can have. So the answer will be 8

Reply 8

CTLeafez

Original post by AortaStudyMore

surely it'll be 2^3, it's asking how many different combinations of the chromosomes you can have. So the answer will be 8

Well YY isn't biologically possible and the question asks for 'types' not 'combinations. If I was taking the exam, I would put 2 but feel free to put 8 :P

Reply 9

username2396569

Original post by CTLevers

maternal and paternal doesn't just refer to the allosomes but to the autosomes too, there are 3 homologous pairs in that cell each made of a maternal and paternal chromosome pair. When the chromosomes line up on the equator during metaphase I they do so randomly (independent segregation) so there is a 2^3 number of combinations that this arrangement can happen in

Reply 10

username2396569

Original post by CTLevers

Well YY isn't biologically possible and the question asks for 'types' not 'combinations. If I was taking the exam, I would put 2 but feel free to put 8 :P

mate did you read the question? It asks for combinations

Reply 11

CTLeafez

Original post by AortaStudyMore

mate did you read the question? It asks for combinations

"How many different TYPES of gametes could be produced from this cell as a result of different combinations of P and M chromosomes?"

Using different combinations of the chromosomes, the question is asking for how many different types can be produced. I'll have a look for the markscheme so we'll know once and for all.

Reply 12

username2396569

Original post by CTLevers

Just take a second to think about what you're saying here haha, the cell in the question is a germ cell right? A germ cell is only going to produce 1 type of gamete in a male and 1 type in a female, males don't make ova and females don't make sperm. You can't get ova and sperm from a germ cell from 1 sex