VCE Biology Question Thread

[vox nihili]

is dna synthesised in the 5 to 3 way, from the primer, in dna replication? always get confused on this haha, tyyy

You and I read from left to right, just like DNA polymerase does—it reads the template strand from 3' to 5' (left to right)

Given the strands are antiparallel, the new strand must then be made 5' to 3'

[esthertham58]

- interactions of environmental factors with genes. Is that like chemical pollutants ( mutagens?)
What else do I need to know about it.

[Butterflygirl]

For the definition of hominin: Humans and bipedal ancestors, in the 2013 exam they mentioned australopithecus africanus as "knuckle walking", and their hominins..

So is it safe to say bipdedal ancestors or human-like ancestors?


Thanks!

[plsbegentle]

For the definition of hominin: Humans and bipedal ancestors, in the 2013 exam they mentioned australopithecus africanus as "knuckle walking", and their hominins..

So is it safe to say bipdedal ancestors or human-like ancestors?


Thanks!

anything with bipedal usually works

[purplegiraffe]

Do we need to know of a negative feedback system?

[blacksanta62]

1) Perhaps write 'chance events which lead to a change in allele frequency. In small populations, this can lead to the loss of alleles and therefore the loss of favourable phenotypes'
Bottleneck effect is good! So is founder effect

That works much better. Thank you

also large foward facing eyes with 3d vision and colour.
Hominin includes the human species and their erect walking ancestors (australopithecus)
Hominoids includes human and great apes.
really what seperates hominin and hominoid is the bipedal gait of hominins.

Nice. Thanks
Another question:
Do cells regulate genes to conserve materials and energy?
Thank you

[vox nihili]

That works much better. Thank you :DNice. Thanks
Another question:
Do cells regulate genes to conserve materials and energy?
Thank you

THat's one reason, yes

[geminii]

Do we need to know of a negative feedback system?

No we don't, that is homeostasis which is not on the study design

[FatimaEl]

Few quick questions
-Difference between mhc markers, class 1 and 2, something about red blood cells too? Can someone clarify this
-In gel electrophoresis, the way the dna moves is towards the positive end yea?
-difference between dna sequencing and dna profiling?
-if a dihybrid test cross comes out as 1:1:1:1, does that mean it is not linked, and that they assort independently?
-how to tell the difference between polygenes and codominance?
-Also, im sorta confused about test crosses, say we need to determine whether the trait is hetero or homo, do we make two crosses both crossed with a recessive homo?

Thank you and good luck everyone!!

[blacksanta62]

THat's one reason, yes

In the case of lac operon, would another reason be the lack of lactose to change the shape of the repressor?
And what are the other reasons? Or are they beyond VCE?
Thanks

[Yacoubb]

In the case of lac operon, would another reason be the lack of lactose to change the shape of the repressor?
And what are the other reasons? Or are they beyond VCE?
Thanks

You don't need to know about the lac operon for this study design! However, the way it works is that when lactose is present, it binds to the repressor, which then means it can no longer attach to the promoter sequence of the gene. As a result, RNA polymerase can transcribe the gene for lactase, as lactase needs to be broken down.

[blacksanta62]

Few quick questions
-The difference between MHC markers, class 1 and 2, something about red blood cells too? Can someone clarify this
-In gel electrophoresis, the way the DNA moves is towards the positive end yea?
-difference between DNA sequencing and DNA profiling?
-if a dihybrid test cross comes out as 1:1:1:1, does that mean it is not linked, and that they assort independently?
-how to tell the difference between polygenes and codominance?

-MHC class 1 are found on all nucleated cells. So that excludes RBC. MHC 2 are found on specific immune cells such as B-cells and cytotoxic T-cells. I also think that they're on T helper cells
Yep. DNA has an overall negative charge and moves towards the positive end of the machine
-DNA profiling is how we determine which people have a corresponding DNA found at a crime scene or whatever. Or to determine the father of a child etc. DNA sequencing allows us to obtain the specific sequence of nucleotides we are interested in. This is used when trying to make GMOs or transgenic organisms
-Someone clarify this, I need some help with linked genes
- With co-dominance, both genotypes should be expressed in the phenotype while with polygenes, they'll be many genes coding for one phenotype.
Hope that was clear

Edit:

You don't need to know about the lac operon for this study design! However, the way it works is that when lactose is present, it binds to the repressor, which then means it can no longer attach to the promoter sequence of the gene. As a result, RNA polymerase can transcribe the gene for lactase, as lactase needs to be broken down.

I think I have the 2017-2021 SD then lol
Thanks for the explaination
Could you explain the linked genes and the independent assortment thing? I always forget what the 1:1... etc. means

[plsbegentle]

Few quick questions
-Difference between mhc markers, class 1 and 2, something about red blood cells too? Can someone clarify this
-In gel electrophoresis, the way the dna moves is towards the positive end yea?
-difference between dna sequencing and dna profiling?
-if a dihybrid test cross comes out as 1:1:1:1, does that mean it is not linked, and that they assort independently?
-how to tell the difference between polygenes and codominance?
-Also, im sorta confused about test crosses, say we need to determine whether the trait is hetero or homo, do we make two crosses both crossed with a recessive homo?

Thank you and good luck everyone!!

MHC 1 markers are on all cells with an nucleus. Red blood cells don't have a nucleus therefore do not have MHC1 markers.
MHC 2 markers are only found on white blood cells, macrophages, b cells, t cells etc.

Yes dna is negatively charged and move towards the positive terminal when a electric current is applied.

Nope, if there is a 1:1:1:1 raio,it can suggest both independent assort or sex linked. However you can tell its linked, if the almost all the % of offspring have the parental gene and only a few who have the recombinant ones. You can also tell if its indepdently assorted when the proportion of offspring are all equal in number.

Well, co-dominant is when both alleles are equally expressed so for example, iAiB, making a AB blood type. Polygenes are when when traits are controlled by two or more genes. Really two different concepts

Test cross is used to determine whether the indivdual is heterozygous or homozygous by crossing it with a homozygous recessive. You only cross once, if u perform a test cross on a homozygous dominant, you'll know it isnt heterozygous based on the proportion of offsprings.

[purplegiraffe]

What do we need to know about action potential?
About Na⁺ and Ca⁺² and that crap

[plsbegentle]

What do we need to know about action potential?
About Na⁺ and Ca⁺² and that crap

Pretty sure action potential isnt required, if it is.. rip me but you need to know about Ca2+ , it basically stimulates the neuron to release the neurotransmitter into the synapse.

Good luck to everyone tomorrow, going to sleep at 9:40 LUL