A2 Biology | Post your doubts here

[angelgirl:)]

please can anyone tell me examples of the effect of the environment on the phenotype??

phenotype is affected from both the genothype as well as the environment...
when a person suffers from malnutrition that is luck of calcuium , although this person has the gene to grow tall but cant becouse he/she is having difficiency disease for this mineral ion...so its gene for tallness is not switch on and cant grow tall...
there r many examples for this Quesuion but i give u explaination just about size....

 

[angelgirl:)]

crossing over occurs between non sister chromatids of homologous chromosomes yeah?

yes...

 

[smartangel]

yup...

thank you i have some other confusions that i"ve posted some time back..probably on the previous page..plz see if you could help me out with them! thanks again. will surely remember you in my prayers

 

[aliya_zad]

crossing over occurs between non sister chromatids of homologous chromosomes yeah?

Yes it does occur between non-sister chromatids.!

 

[smartangel]

are you guys doing the application part frm ocr or the booklet..or both? i dont have much time so where should i do it frm?

 

[Asha Tabassum]

Why there is no advantage for Sickel cell anaemia allele outside of malarial areas?????????????

 

[aliya_zad]

Why there is no advantage for Sickel cell anaemia allele outside of malarial areas?????????????

Coz ull die of Sickle cell anaemia..

 

[Asha Tabassum]

Coz ull die of Sickle cell anaemia..

could you xplain m in details plzz...

 

[angelgirl:)]

aliya_zad said: ↑

Coz ull die of Sickle cell anaemia..​

could you xplain m in details plzz...
even i wanna know?​

 

[omair tahir]

Sickle cell anaemia is a disease which cannot be cured... Whether u r inside or outside the malarial area
U r still resistant tO malaria but ull die of sickle cell anaemia
Except the gene causing it is replaced .. Thts wht i think
Plx correct me if i am wrong

 

[angelgirl:)]

Sickle cell anaemia is a disease which cannot be cured... Whether u r inside or outside the malarial area
U r still resistant tO malaria but ull die of sickle cell anaemia
Except the gene causing it is replaced .. Thts wht i think
Plx correct me if i am wrong

arent they just talking about the allel for the sickle cell anaemia...that is getting increasd not the sickle cell disease

 

[angelgirl:)]

thank you i have some other confusions that i"ve posted some time back..probably on the previous page..plz see if you could help me out with them! thanks again. will surely remember you in my prayers

can u post ur doubts again so that others can answer...as iam running out of time...

 

[omair tahir]

I think the only advantage for sickle cell trait is survival
There r no advantage other thn restistant to malaria nd is only carrier of disease

 

[aliya_zad]

could you xplain m in details plzz...

When u are in malarial areas the heterozygous form of sickle cell anaemia is beneficial/is more favourable..coz when u have malaria ur red blood cells are affected,they burst and u die of less o2 being transported..and hence nature selects the more favourable characteristic and thats the likelihood of having the gene for sickle cell anaemia.

In places where malaria is not prevalent having the gene for sickle cell anaemia is not at all beneficial..and hence nature selects the normal allele over sickle cell anaemia..(SCA)

Malaria is a severe form of disease compared to SCA ...which is why in malarial areas u tend to have SCA than malaria..but in non malarial regions y have SCA coz they are not at all beneficial..

 

[angelgirl:)]

When u are in malarial areas the heterozygous form of sickle cell anaemia is beneficial/is more favourable..coz when u have malaria ur red blood cells are affected,they burst and u die of less o2 being transported..and hence nature selects the more favourable characteristic and thats the likelihood of having the gene for sickle cell anaemia.

In places where malaria is not prevalent having the gene for sickle cell anaemia is not at all beneficial..and hence nature selects the normal allele over sickle cell anaemia..(SCA)

Malaria is a severe form of disease compared to SCA ...which is why in malarial areas u tend to have SCA than malaria..but in non malarial regions y have SCA coz they are not at all beneficial..

totally agree with u as i have the same opinion...

 

[omair tahir]

When u are in malarial areas the heterozygous form of sickle cell anaemia is beneficial/is more favourable..coz when u have malaria ur red blood cells are affected,they burst and u die of less o2 being transported..and hence nature selects the more favourable characteristic and thats the likelihood of having the gene for sickle cell anaemia.

In places where malaria is not prevalent having the gene for sickle cell anaemia is not at all beneficial..and hence nature selects the normal allele over sickle cell anaemia..(SCA)

Malaria is a severe form of disease compared to SCA ...which is why in malarial areas u tend to have SCA than malaria..but in non malarial regions y have SCA coz they are not at all beneficial..

Its about having advantage
Outside malarial area u dont have any advantage of having Sickle cell trait But in malarial area there is an advantage that u dont die becoz of sickle cell or malaria

 

[angelgirl:)]

I think the only advantage for sickle cell trait is survival
There r no advantage other thn restistant to malaria nd is only carrier of disease

ya dats true...

 

[angelgirl:)]

Its about having advantage
Outside malarial area u dont have any advantage of having Sickle cell trait But in malarial area there is an advantage that u dont die becoz of sickle cell or malaria

dats wat Aliya_zad meant..

 

[Asha Tabassum]

When u are in malarial areas the heterozygous form of sickle cell anaemia is beneficial/is more favourable..coz when u have malaria ur red blood cells are affected,they burst and u die of less o2 being transported..and hence nature selects the more favourable characteristic and thats the likelihood of having the gene for sickle cell anaemia.

In places where malaria is not prevalent having the gene for sickle cell anaemia is not at all beneficial..and hence nature selects the normal allele over sickle cell anaemia..(SCA)

Malaria is a severe form of disease compared to SCA ...which is why in malarial areas u tend to have SCA than malaria..but in non malarial regions y have SCA coz they are not at all beneficial..

thank you

 

[aliya_zad]

Its about having advantage
Outside malarial area u dont have any advantage of having Sickle cell trait But in malarial area there is an advantage that u dont die becoz of sickle cell or malaria

..which is why i used the word beneficial/favourable..
Advantage, beneficial/favourable..they all mean the same thing..don't they??