VCE Biology Question Thread

[shivaji]

are all phagocytes antigen presenting cells or are only macrophages APCs?

[shan_19]

On homologous chromosomes, will one allele for a gene be on each chromosome, or will both alleles be on one of the homologous chromosomes?

Chromosome 1: A
Chromosome 2: a
OR
Chromosome 1: Aa

[vox nihili]

On homologous chromosomes, will one allele for a gene be on each chromosome, or will both alleles be on one of the homologous chromosomes?

Chromosome 1: A
Chromosome 2: a
OR
Chromosome 1: Aa

What do you think and why?

[shan_19]

What do you mean by this?

Macrophages engulf and destroy invading pathogens, like bacteria. But do macrophages do the same for viruses, fungi, protists etc?

[shan_19]

What do you think and why?

Well, I just assumed it was one allele on each chromosome...

[vox nihili]

Well, I just assumed it was one allele on each chromosome...

That's right (Y)

You can have multiple copies of the same allele on each chromosome though too But it will have another copy on the other.

[shivaji]

Do memory cells circulate just in the lympthatic system or the blood system too?

[Reus]

Do memory cells circulate just in the lympthatic system or the blood system too?

Both

[alondouek]

in hominins, is the foramen magnum located at -the centre of the base of the skull,
                                                                 OR     - base of the skull
                                                                 OR     - centre of the skull ?

In hominins, it is located at the centre of the skull so that the skull can be fully balanced and supported while walking.

Although your reasoning re: effect on bipedal mobility is generally correct, you haven't got the right option. The correct selection is the first one; the foramen magnum is located at the centre of the base of the skull.

Here's a picture to demonstrate this:

The foramen magnum is the big hole in the centre of the base of the skull (occipital bone). As you may be able to infer, it houses the spinal cord from its origin at the base of the brain.

[nerdmmb]

A question from the 2013 VCAA exam asked why booster injections need to be given and the answer was that memory cells are short lived and that's why booster injections need to be given.

So with that in mind, would it be wrong to say that vaccines provide long term immunity?

Also, where can I find the answers to the 2013 VCAA Sample exam?

Thanks

[alondouek]

A question from the 2013 VCAA exam asked why booster injections need to be given and the answer was that memory cells are short lived and that's why booster injections need to be given.

So with that in mind, would it be wrong to say that vaccines provide long term immunity?

Also, where can I find the answers to the 2013 VCAA Sample exam?

Thanks

I don't think you would be wrong to say that vaccination is intended to provide long-term immunity; booster injections are just a part of the overall vaccination process.

[Scooby]

are all phagocytes antigen presenting cells or are only macrophages APCs?

Nope. Neutrophils, for example, are phagocytic, but don't present antigens. B cells aren't phagocytes but some are capable of antigen presentation. Macrophages and dendritic cells are phagocytes and antigen presenters.

[Reus]

Nope. Neutrophils, for example, are phagocytic, but don't present antigens. B cells aren't phagocytes but some are capable of antigen presentation. Macrophages and dendritic cells are phagocytes and antigen presenters.

APC's are basically cells with MHC II markers right?

[Reus]

Could someone kindly explain to me how q25 on the 2013 exam MC is done? I can't get my head around it :/ Thanks!

[Scooby]

APC's are basically cells with MHC II markers right?

Pretty much

Could someone kindly explain to me how q25 on the 2013 exam MC is done? I can't get my head around it :/ Thanks!

Okay, so we have four children, and each of them has a different blood type. So, we know that the parents need to have genotypes that make it possible for offspring of with any blood type to be produced.

An offspring with blood type O has genotype "i i" - so both parents need to have this "i" allele

An offspring with blood type AB has genotype "I^A I^B" - one of these alleles was inherited from the mother and the other from the father. Regardless, one of the parents needs to have an "I^A" allele, and the other needs to have an "I^B" allele

Therefore, the parental genotypes are "I^A i" (which corresponds to blood type A) and "I^B i" (which corresponds to blood type B)

We can see that with these genotypes, it's possible to produce offspring with any of the four blood types

So it's B