Past paper Questions

[sidzeman]

The answers say B which has me confused
I understand muscles contract to raise hairs, but shouldn't the arteriole walls expand (vasodiliation) so that there is increased blood flow and therefore heat?

For the genotype question, I'm not sure how to approach it at all

[pikachu975]

The answers say B which has me confused
I understand muscles contract to raise hairs, but shouldn't the arteriole walls expand (vasodiliation) so that there is increased blood flow and therefore heat?

For the genotype question, I'm not sure how to approach it at all

Well the right column is a distractor. You can deduce it's B from the left hand column.

Anyway, vasodilation brings blood closer to the skin so that when the wind blows on you, you will be cooled by evaporative cooling I guess, which is what kangaroos use too. Also vasodilation and sweating are the common responses used for thermoregulation in hot weather.

[idontlikeschool]

Q15 is tough. It tells you that the experiment mimics Mendel's. So i would assume that seeing as though that's the case, the 2 original parent plants would need to be purebreds. So RR & rr is the answer.

[sidzeman]

Actually the answer was C RR and YY - which are purebred parents i see okay THANKS!

[Opengangs]

Hi, sidzeman!

To really understand that question, let's consider the question again.
It tells us that there are three phenotypes, which means that there may be a case of codominance happening, where both dominant alleles are fully expressed. This means that for an orange flower to occur, there must be a RY happening.

Now, we know that the cross is of a different flower colour, which means it can't be something like RR and Rr, or Rr and Rr.
Lastly, we know that three phenotypes were expressed after the cross. This means it can't be anything with a dominant AND and a recessive allele, such as RR and rr, since that will only express two phenotypes.

Thus, we can rule out (B).
Now, we need to determine if they were pure bred or not.
Since it follows Mendel's experiments, the parents would have been purebred, which means that the genotypes are: RR and YY.

[sidzeman]

Thats a really thorough explanation opengangs haha thank you so much