VCE Biology Question Thread

[RazzMeTazz]

For the question (part e.) attached below I answered:

The geneticist should perform a cross with two organisms which are heterozygous for both traits (pigment and wing length) and if the correct 9:3:3:1 ratio are produced, the traits are independently assorted but if the number of parental phenotypes is much greater than the number of recombinant phenotypes the genes are linked and hence not independently assorted.

However the correct answer is "The geneticist would have to perform a test cross by crossing an individual that is heterozygous at both loci with an individual that has both recessive traits. If the geneticist is correct the phenotypic ratio of the offspring should be 1:1:1:1

Would my answer still be correct? Since they are both based on known phenotype ratios for unlinked traits? Or is it still wrong? If so why?

Thanks!

[vox nihili]

Anyone know answers for E,F or G?    (Btw G is 1 mark)

 

Show us how you answered it first

[althepal]

Is meiosis part of the cell cycle? Or is that only mitosis

[jessica666]

Is meiosis part of the cell cycle? Or is that only mitosis

Yep it is there is a mitotic cell cycle, and a meiotic cell cycle

[mahler004]

VCAA Exam 2 2009 q1c: Explain why apoptosis sometimes occurs during the cell cycle represented in the above diagram.

My answer: Apoptosis may occur if there is an error during DNA replication

Suggester answer: Either of:
• a fault has occurred such as spindles break or chromosomes fail to separate
• cells produced are unable to function/not required.

is my answer still correct?

The cell will attempt to repair the error. This is usually possible, but if the error cannot be repaired, the cell enters apoptosis.

[shivaji]

If asked to describe the structure of a tRNA molecule, would it suffice to say that on one end there is an anticodon, and on the other end there is a corresponding amino acid? Or does extra information have to be given, and if so can  someone explain what extra information please?

Thanks

[shivaji]

Are antigens displayed on MHC Markers?

So when asked how does an immune cell differentiate self from non-self molecules, is this a suitable response:

Immune cells have receptors which are able to identify the antigen presented on MHC markers of nucleated cells, and recognise whether these antigens are self or non'self.

[howlingwisdom]

If asked to describe the structure of a tRNA molecule, would it suffice to say that on one end there is an anticodon, and on the other end there is a corresponding amino acid? Or does extra information have to be given, and if so can  someone explain what extra information please?

Thanks

I'd say that on one end there is an anticodon and there is a specific amino acid binding site on the other end. (I think that's all that we might be required to know?)

[RazzMeTazz]

Would it be correct to assume that in order to date organic matter only carbon-14 dating can be used (provided organism is less than 50,000 years old) as the other radioactive parent isotopes of Uranium-235, Potassium-40 and Rubidium-87 are not found in organic matter?

[vox nihili]

Is gene regulation on the study design?

This tells you what's on the study design

[theBRENDAN97]

In unit 3 AOS2, what do we specifically need to know, I've got:
-lipid and protein based hormones
-neurotransmitters, animal hormones, pheromones, plant hormones and neurohormones.
-signal transduction
-apoptosis (intrinsic and extrinsic causes)
-neurotransmitter across synapse

But is it smart to know about homeostasis and sodium-potassium pumps (because the faq is confusing)?

In the study design what does it mean by stimulus response model (and at a cellular level), and roles of the nerve pathway and chemical signals in the transmission of information from receptor to effector?
 (we didn't go in too much detail at all in class).
Any advice, would be greatly appreciated. Thanks.
How's everyone else going, with the exam in less than a week?

[Reus]

In unit 3 AOS2, what do we specifically need to know, I've got:
-lipid and protein based hormones
-neurotransmitters, animal hormones, pheromones, plant hormones and neurohormones.
-signal transduction
-apoptosis (intrinsic and extrinsic causes)
-neurotransmitter across synapse

But is it smart to know about homeostasis and sodium-potassium pumps (because the faq is confusing)?

In the study design what does it mean by stimulus response model (and at a cellular level), and roles of the nerve pathway and chemical signals in the transmission of information from receptor to effector?
 (we didn't go in too much detail at all in class).
Any advice, would be greatly appreciated. Thanks.
How's everyone else going, with the exam in less than a week?

Stimulus response model is the stimulus --> receptor --> modulator --> effector --> response

[RazzMeTazz]

What is the purpose of the methylated cap and Poly-A-Tail being added to pre-mRNA during post transcription modification to form mRNA?

I thought it was to prevent the mRNA molecule from enzymatic degradation in the cytoplasm but many practice exam company papers seem to state that the purpose of them is to ensure correct orientation of the mRNA when it is read by the ribosome.

Would both answers be correct?

[Reus]

What is the purpose of the methylated cap and Poly-A-Tail being added to pre-mRNA during post transcription modification to form mRNA?

I thought it was to prevent the mRNA molecule from enzymatic degradation in the cytoplasm but many practice exam company papers seem to state that the purpose of them is to ensure correct orientation of the mRNA when it is read by the ribosome.

Would both answers be correct?

They work as a guide for translation, movement and to lock in the mRNA sequence so no other nucleotide can bind.

[vox nihili]

What is the purpose of the methylated cap and Poly-A-Tail being added to pre-mRNA during post transcription modification to form mRNA?

I thought it was to prevent the mRNA molecule from enzymatic degradation in the cytoplasm but many practice exam company papers seem to state that the purpose of them is to ensure correct orientation of the mRNA when it is read by the ribosome.

Would both answers be correct?

The cap there is, like Reus said, as a guide for translation. It just tells the ribosome which end is which (very basically). The more complicated answer is that the ribosome binds to the cap and then assemblies itself. Only then does it start translating.

The Poly A tail, however, does prevent degradation and helps to stabilise the mRNA molecule.

You don't need to know any of this