Edexcel Unit 1 Biology Higher, thoughts?

Original post by JamieGre

I got 75%.

It said the person can't have it but is a carrier so that's how I got 50% as there was one with two recessive and one with a homozygous dominant for not having it. That left two heterozygous, which were dominant.

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Reply 63

Original post by vik_k1

For the sickle cell one, did you get 50% for the probability one?Posted from TSR Mobile

Original post by JamieGre

I got 75%.

Same here. Sickle cell is a recessive type.
It said to draw one for heterozygous parents.
and the % for probability of not getting it ^^

Reply 64

Original post by vik_k1

Nope. the question said heterozygous parent(s);
meaning there was
1 homozygous dominant (for not having it)
2 heterozygous
1 recessive.

I would say 75%, because carriers don't actually have the disease they can only pass it on.

Reply 65

Original post by Zellaforever

did you write vasdilation or vasconstriction

that was one was difficult. i put vasodilation because it said when the body is trying not to lose heat (right?) and so vasodilation is when less heat is transferred to the environment and vasoconstriction is when more heat is transferred to the environment. so, i would imagine it to be vasodilation.

then again, i could be wrong.

Reply 66

Original post by aesking

You got it the wrong way round. Dilate means widen. When the blood vessels dilate (vasodilation) more blood is flowing near the surface of the skin allowing more heat to transfer to the surroundings. When blood vessels constrict (vasoconstriction) less blood is flowing near the surface of the skin so less blood is getting transferred to the surroundings.

The answer was vasoconstriction because it asked how blood vessels reduce the amount of heat loss (something like that)

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Reply 67

Original post by DamnDaniel2

Yeah I just realised. :eek:

Daaamnn.

Was there any other question revolving around vasodilation/vasoconstriction? I remember the question about how the part of the brain that controls thermoregulation. But that's it. :smile:

I can't believe I got those two mixed up.

(edited 7 years ago)

Reply 68

Original post by aesking

It can't be someone who has got it-'ff' so that eliminates 25% and the other person would have 'FF' alleles as if its heterozygous it would be 'FF'. Therefore, 50% is the answer.

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Reply 69

Original post by vik_k1

Uh, no 75% -- and to prove it to you I've done a punnet square table:
Screen Shot 2016-05-17 at 18.43.05.png

RR = is the homozygous DOMINANT - meaning they DON'T HAVE it because it's a RECESSIVE TYPE (rr).

Rr is a carrier. (because despite one being dominant, you need 2 recessive alleles. if it was a dominant type then that would be a different question as you need either a BB or Bb to have the disease or bb to NOT get it.)

rr is where you do have it

so the chance of not getting it is: 75%.

(edited 7 years ago)

Reply 70

legend.786

The question was the chance of being a carrier but not actually being a sufferer therefore it is 50 percent

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Reply 71

legend.786

Can anyone tell me if this is correct i wrote that wen light shines on the shoot the auxins distribute to the shaded side and the make the growth faster and they cause cell elongation so that part will grow but the top will be slow so it will end up curving. I also wrote that the plant will react to the stimulus and the change if environment .

Will this get me the marks thanks

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Reply 72

Original post by legend.786

The question was the chance of being a carrier but not actually being a sufferer therefore it is 50 percent
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All the question said: was the probability of not getting it. I remember it quite clearly and it didn't mention anything about a carrier vs. a sufferer.

Reply 73

Original post by aesking

Uh, no 75% -- and to prove it to you I've done a punnet square table:
Screen Shot 2016-05-17 at 18.43.05.png

So that means that RR won't be a carrier. 'rr' has it, so we need to work out just the carriers who don't have it. These are 'Rr' and 'Rr'. Meaning it's 50%. The punnet square is right, you don't count 'RR' because they're NOT carriers.

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Reply 74

Original post by legend.786

The question was the chance of being a carrier but not actually being a sufferer therefore it is 50 percent

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I got 50%, most people at school got 50% as well!

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Reply 75

Original post by aesking

Uh, no 75% -- and to prove it to you I've done a punnet square table:
Screen Shot 2016-05-17 at 18.43.05.png

The question was who would be a carrier but not actually have it. The answer is 50% because as you have shown there are two 'Rr's and to have the disease you would need two recessives so it could not have been 'rr' and it could not have been 'RR' because then that would mean the person is not even a carrier.

The answer was 50% and not 75%

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Reply 76

Original post by vik_k1

Omg, do you understand your logic? The question was the probability of not getting the disease, not the likelihood of the carriers - meaning that you do COUNT the RR.

Reply 77

No it said who would be a carrier but not actually be a sufferer.

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Reply 78

Original post by aesking

Omg, do you understand your logic? The question was the probability of not getting the disease, not the likelihood of the carriers - meaning that you do COUNT the RR.

Mate sorry you lost some marks. The answer was 50% it clearly said that the chances of being a carrier and not a sufferer.

The effects of skim reading kids. Do not do this for the C1 exam on thursday :smile:

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Reply 79