Biology 2013ers MARATHONN (1 Viewer)

[superSAIyan2]

It is rare to find a female with a sex-linked disease such as haemophilia or red-green colour blindless. Justify this statement. [3]

Haemophilia and red-green colour blindness are X-linked recessive disorders and as a result females require two recessive alleles on the X chromosome to express the condition, whereas males only need one. Also females can be carriers for the disease; they can possess the recessive allele but this will be masked from the phenotype by a dominant allele. Hence it is rare to find females with a sexlinked disease.

A red cow and a white cow mated to produce four offspring: 1 was red, 1 was white and 2 were pink. Explain this type of inheritance and why it does not follow Mendelian ratios. 3M

 

[obliviousninja]

Haemophilia and red-green colour blindness are X-linked recessive disorders and as a result females require two recessive alleles on the X chromosome to express the condition, whereas males only need one. Also females can be carriers for the disease; they can possess the recessive allele but this will be masked from the phenotype by a dominant allele. Hence it is rare to find females with a sexlinked disease.

A red cow and a white cow mated to produce four offspring: 1 was red, 1 was white and 2 were pink. Explain this type of inheritance and why it does not follow Mendelian ratios. 3M

for these questions can u draw pedigree, list cases, etc. and give a short explanation

 

[bedpotato]

for these questions can u draw pedigree, list cases, etc. and give a short explanation

If you mean punnet squares, yes you can.

Bio teacher takes marks off if we don't draw punnet squares where appropriate :/

 

[ForOneEon]

for these questions can u draw pedigree, list cases, etc. and give a short explanation

I'd assume "Yes, you can draw a pedigree if given enough space."

The correct term the co-dominant colour combination is roan though, right?

Normally, I would draw a Punnett square to show the codominance with ratios and all. The pedigree only shows what ones have the specific colour, not really effective in this case.

 

[bedpotato]

Haemophilia and red-green colour blindness are X-linked recessive disorders and as a result females require two recessive alleles on the X chromosome to express the condition, whereas males only need one. Also females can be carriers for the disease; they can possess the recessive allele but this will be masked from the phenotype by a dominant allele. Hence it is rare to find females with a sexlinked disease.

A red cow and a white cow mated to produce four offspring: 1 was red, 1 was white and 2 were pink. Explain this type of inheritance and why it does not follow Mendelian ratios. 3M

Yep, but also mention the size of the chromosomes.
I had the same answer, but only got 2/3 because didn't mention size >.<

 

[hamstar]

If you mean punnet squares, yes you can.

Bio teacher takes marks off if we don't draw punnet squares where appropriate :/

Bio Teacher also takes marks off (or does not award marks) if you have not completed the table. Everything should be closed.

 

[Menomaths]

Didn't even know about this...

 

[bedpotato]

What really? So the size of the chromosomes are different in codominance?

No lol.
That was meant for sex-linkage.

 

[Spiritual Bean]

what

lol...


who's screwed like me?

 

[Menomaths]

No lol.
That was meant for sex-linkage.

Oh...

 

[DJ696]

what

lol...


who's screwed like me?

biology doesn't even count for me as i do 12 units and its my worst 2 unit subject

 

[Spiritual Bean]

biology doesn't even count for me as i do 12 units and its my worst 2 unit subject

nice bro

atar before bio: 99.7

after bio: 89

bad luck brian

 

[DJ696]

nice bro

atar before bio: 99.7

after bio: 89

bad luck brian

Atar before: 99.95
after biology: mystery mark

 

[obliviousninja]

If you mean punnet squares, yes you can.

Bio teacher takes marks off if we don't draw punnet squares where appropriate :/

gg. pedigree...lol

 

[abcderic]

Haemophilia and red-green colour blindness are X-linked recessive disorders and as a result females require two recessive alleles on the X chromosome to express the condition, whereas males only need one. Also females can be carriers for the disease; they can possess the recessive allele but this will be masked from the phenotype by a dominant allele. Hence it is rare to find females with a sexlinked disease.

A red cow and a white cow mated to produce four offspring: 1 was red, 1 was white and 2 were pink. Explain this type of inheritance and why it does not follow Mendelian ratios. 3M

Is this something like incomplete dominance? If not what is incomplete dominance?..

 

[bedpotato]

Is this something like incomplete dominance? If not what is incomplete dominance?..

co-dominance

idek anymore

 

[abcderic]

Hm, I thought incomplete dominance was the blending of both alleles, hence the pink fur coat from red and white parents.

 

[bedpotato]

Hm, I thought incomplete dominance was the blending of both alleles, hence the pink fur coat from red and white parents.

Yeah, got it mixed up with the cattle colour - red, white, roan.

 

[leesh95]

Co-dominance --> Both alleles expressed in phenotype e.g. roan cattle
Incomplete dominance --> Blended characteristics e.g. white and red flower gives pink

 

[superSAIyan2]

Is this something like incomplete dominance? If not what is incomplete dominance?..

co-dominance

idek anymore

Its incomplete dominance since the phenotype is a blend. Codominance is when both phenotypes are expressed simultaneously; i.e. the cow would have red and white spots