VCE Biology Question Thread

[Sine]

Here comes my post-exam influx:

Question 13:

 Isnt apoptosis only initiated from signals exterior to the cell? If not, then can someone give an example of an interior signal, is it as simple as the DNA is altered so it signals death?

Second part to it is, why would perfectly healthy cells be programmed to die? Answer is D

Question 17:

Where does it say/ how do we know that the lactase is a selective advantage? I said D is the answer can someone explain why D is incorrect?

Question 18:

How do primers anneal? Doesn't the DNA primase (RNA Polymerase) synthesise the primers onto the DNA template strands?

Question: When you write the phenotypic ratio, if you are dealing with males and females, is the normal female a different phenotype as the normal male, right?

Question: What is a polygenic inheritance?
"A trait that is inherited in more than one gene locus"
Is this correct?

Q13: Apoptosis occurs in webbing in hands and feet in humans also interior signal such as incorrect DNA replication will result in apoptosis.

Apoptosis is regulated cell death. i.e cells that are no longer required.

Q17: I got this one wrong when I was doing it too honestly don't really have an explanation, maybe because it's in 90% of Europeans so kinda indirectly states that it's been selected for.

Q18: primers anneal by cooling DNA to 55 degrees Celsius

This is PCR not DNA replication.


Yes always specify sex when using ratios for X-linked traits.

Polygenic inheritance is where many genes code for a particular phenotype which has continuous variation.

Your explanation is kinda vague and I would expect vcaa to want something very close to the answer the provide for this.

EDIT: beaten by Mr. T-Rav and Bruzzix

[sushibun]

Thank you!

[BakedDwarf]

thanks Mr. T-Rav

What does "the disease has not yet been switched on" mean? You said it didn't relate to genes being switched on, so i'm confused. Pls halp.

[paper-back]

Does anyone know where I can find a list of the changes in structure that occurred during hominin evolution and what they allowed for/suggests?
E.g. A decrease in arm to leg ratio suggests that (species) began to move from trees to ground

Do we need to know the structural differences between 2 different species of hominin?

[vox nihili]

Q13: Apoptosis occurs in webbing in hands and feet in humans also interior signal such as incorrect DNA replication will result in apoptosis.

Apoptosis as it occurs in the webbing in hands and feet is initiated by external signals Otherwise, how do the cells know whether they should die or not? The cells don't know that they're part of the webbing unless they're told by external signals.

thanks Mr. T-Rav

What does "the disease has not yet been switched on" mean? You said it didn't relate to genes being switched on, so i'm confused. Pls halp.

Yeah really rough question. They're talking about an autoimmune condition. Whether or not the disease comes about will have more to do with the environment than gene expression. An environmental trigger needs to activate the autoimmune disease. This could, for instance, be an infection. The cells are already there ready to attack the body, but they're not activated until the environment presents.

[Biology24123]

For the anatomical traits that cause bipedalism, do we need to know how they cause bi pedalism?

[Biology24123]

How is reduced eye brow ridges a selective advantage?

[sunshine98]

Because I always tend to forget to add the word 'specific' in my answers , I thought it would be helpful (for all of us , hopefully) to make a list of things that require it. Let me start off:
- specific antibodies
-specific amino acid on tRNA
- specific receptors
-specific antigen binding site
-specific enzymes
So I don't have anything else , anyone?

[plants]

How is reduced eye brow ridges a selective advantage?

There's no one answer to that question. I'd suspect there'd be a variety of answers to that if it came up on the exam. Some include:
- allows better upward vision with tilting one's head up
- makes the skull lighter and therefore more mobile - especially when walking upright rather than on all 4 limbs
- decreased brow ridge comes with a change in diet/technological evolution: adaptations for heavy chewing are not needed any more, changing the architecture of the skull, indirectly resulting in a reduced brow ridge.
- Maybe early humans preferred others with less pronounced brows

[Biology24123]

Because I always tend to forget to add the word 'specific' in my answers , I thought it would be helpful (for all of us , hopefully) to make a list of things that require it. Let me start off:
- specific antibodies
-specific amino acid on tRNA
- specific receptors
-specific antigen binding site
-specific enzymes
So I don't have anything else , anyone?

'Complementary' is just as important

[Bruzzix]

There's no one answer to that question. I'd suspect there'd be a variety of answers to that if it came up on the exam. Some include:
- allows better upward vision with tilting one's head up
- makes the skull lighter and therefore more mobile - especially when walking upright rather than on all 4 limbs
- decreased brow ridge comes with a change in diet/technological evolution: adaptations for heavy chewing are not needed any more, changing the architecture of the skull, indirectly resulting in a reduced brow ridge.
- Maybe early humans preferred others with less pronounced brows

I always thought that a reduced brow ridge just occurred as a result of having increased cranial capacity and didn't have any particular survival advantage.

[Biology24123]

There's no one answer to that question. I'd suspect there'd be a variety of answers to that if it came up on the exam. Some include:
- allows better upward vision with tilting one's head up
- makes the skull lighter and therefore more mobile - especially when walking upright rather than on all 4 limbs
- decreased brow ridge comes with a change in diet/technological evolution: adaptations for heavy chewing are not needed any more, changing the architecture of the skull, indirectly resulting in a reduced brow ridge.
- Maybe early humans preferred others with less pronounced brows

Thanks. Hate questions that ask for selective advantages of certain features 

[cosine]

When you say that primers anneal passively onto the DNA template strands, how is this possible if this cannot occur in DNA replication? Should I just accept that Primers attach passively during PCR and during DNA replication, they are synthesised by RNA polymerase (DNA primase)?

Because aren't both PCR and DNA replication technically both replicating the DNA?

Edit: Is it because in PCR, the temperature is at 54 degrees, but in DNA rep, it's inside the body so <37? That is the only logical reasoning i can think of..

[Biology24123]

When you say that primers anneal passively onto the DNA template strands, how is this possible if this cannot occur in DNA replication? Should I just accept that Primers attach passively during PCR and during DNA replication, they are synthesised by RNA polymerase (DNA primase)?

Because aren't both PCR and DNA replication technically both replicating the DNA?

Edit: Is it because in PCR, the temperature is at 54 degrees, but in DNA rep, it's inside the body so <37? That is the only logical reasoning i can think of..

I guess different enzymes are involved as well

[sunshine98]

When you say that primers anneal passively onto the DNA template strands, how is this possible if this cannot occur in DNA replication? Should I just accept that Primers attach passively during PCR and during DNA replication, they are synthesised by RNA polymerase (DNA primase)?

Because aren't both PCR and DNA replication technically both replicating the DNA?

Edit: Is it because in PCR, the temperature is at 54 degrees, but in DNA rep, it's inside the body so <37? That is the only logical reasoning i can think of..

Cells don't have primers, they must synthesise them (btw is it DNA primase or RNA primase that synthesis them? I was told RNA primase) . But the PCR machine has a source of primers , all that needs to be done is that it needs to be attached , which occurs passively.