aqa a level biology help

I don't understand the answer to this question, does anyone have any ideas?

Question:
- - - - -
Microinjection of DNA into fertilised egg cells is a frequent method of
producing transgenic fish. However, the insertion of the transferred gene
into nuclear DNA may be delayed. Consequently, the offspring of
transgenic fish may not possess the desired characteristic.

Suggest and explain how delayed insertion of the GH gene could produce
offspring of transgenic fish without the desired characteristic. (2)
- - - - - - - -

MS:

1. Cell division has occured (before gene added)
Accept mitosis but reject meiosis

2. Cells producing gametes do not receive the gene
OR
DNA replication has occured

- - - - - - -

i thought DNA replicated for meiosis but why does it say mitosis here?

i'm thinking that the cells producing the gametes need to divide a lot (by mitosis) before they produce large amounts of gametes, but i'm really not sure. any help?

Reply 1

MedApplicantttt

14

what year was this if you don't mind me asking, seems like a tough one

Reply 2

GhostHawk

OP

8

Original post by MedApplicantttt

what year was this if you don't mind me asking, seems like a tough one

i got it off PMT but i think it's June 2020 paper 2

(edited 1 year ago)

Reply 3

MedApplicantttt

14

Original post by GhostHawk

i got it off PMT but i think it's June 2021

i'd maybe look into the examiner report and see how students coped with this question. normally it does say in examiner reports how many students scored full marks. if it's a small proprtion, there's rlly no point stressing about the question as ultimately bio grade boundaries are low and not all marks are needed for a high grade. hope this helps :smile:

Reply 4

GhostHawk

OP

8

Original post by MedApplicantttt

i'd maybe look into the examiner report and see how students coped with this question. normally it does say in examiner reports how many students scored full marks. if it's a small proprtion, there's rlly no point stressing about the question as ultimately bio grade boundaries are low and not all marks are needed for a high grade. hope this helps :smile:

thanks for the suggestion, but unfortunately for june 2020 there seems to be no examiner reports released. on the aqa website it just skips from 2021 to 2019, 2018 etc. maybe due to covid there were no examiner reports that year?

(edited 1 year ago)

Reply 5

ganyu

8

in short the egg cell was already fertilised thus being a zygote which divides by mitosis

(edited 1 year ago)

Reply 6

GhostHawk

OP

8

Original post by ganyu

in short the egg cell was already fertilised thus being a zygote which divides by mitosis

that makes sense. for the 2nd point "Cells producing gametes do not receive the gene", what does it mean by "cells producing gametes"? surely it should just say something like 'the fertilised egg cells do not receive the gene'? it's so confusing

Reply 7

ganyu

8

essentially cell division by mitosis occurs in the zygote (the original fish) before the transgene enters the genome, so the cells (in the original fish) that make the gametes also do not contain the transgene. So as these gametes dont contain the transgene then the zygote which grows into the offspring also does not posses the transgene. i hope this makes sense :smile:

(edited 1 year ago)

Reply 8

GhostHawk

OP

8

Original post by ganyu

essentially cell division by mitosis occurs in the zygote (the original fish) before the transgene enters the genome, so the cells (in the original fish) that make the gametes also do not contain the transgene. So as these gametes dont contain the transgene then the zygote which grows into the offspring also does not posses the transgene. i hope this makes sense :smile:

ohhhh! i didn't realise we were dealing with 2 different fish populations here!! that makes complete sense. tysm!!!! )))

(edited 1 year ago)

aqa a level biology help

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