VCE Biology Question Thread

[Maca 13]

I think you may have gotten a bit mixed up here. SySy is monohybrid. So SySy is dominant. Sysy heterozygous, sysy homozygous recessive.
What you're looking for is SSYY which would indicate that the organism is homozygous dominant for the S and Y trait. But yeah, what you asked was a organism which was homozygous dominant for the trait.

Hi, thanks for your answer. Does it matter if S=smooth shape, and s=wrinkled and Y=yellow, and y=green, therefore being different traits (S and Y)?

[Sine]

Hey guys hopefully going to receive my SAC marks for my 7th Sac tomorrow! Everyone wasn't quite sure of how they went and the difficulty was felt however I'm pretty confident.(but you never now with bio)
How long does it take your teachers to mark your SACs and give them back, I've been waiting for about a week and my teacher says that she can't even give our scores(without the actual SAC) to us since 1 student hasn't completed it.
For one of my Sacs we were literally waiting for nearly a month.

Also my teacher says that they send a total score out of 200(ranked obviously) to VCAA and that you get a single rank for Unit 3 & 4, however everywhere else I am inclined to believe that these units are separate which would make sense since they are separated grades:GA1, GA2. (just curious)

[Biology24123]

A week is fine. My last one was 2 weeks and haven't got it back

[Biology24123]

Written as SSYY and is homozygous for both traits

[Maca 13]

Written as SSYY and is homozygous for both traits

Ah OK, thanks! I think I got confused as to how to write it before.

[cosine]

Someone willing to explain natural selection to me in simple words?

[BakedDwarf]

Someone willing to explain natural selection to me in simple words?

Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring

[cosine]

Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring

May you give an example of this? What happens to the organisms that are not well suited as the others?

[Biology24123]

May you give an example of this? What happens to the organisms that are not well suited as the others?

Using turtles as an example

Not all turtles will survive
There is variation within the turtle population (some more suited to environment)
Selective pressures allow turtles with a advantageous genes to survive
Turtles with the advantageous gene pass it on to their offspring
Over generations, the frequency of turtles with the gene will be higher than those without
Note: Selective pressures are always changing so the gene may become advantageous

[cosine]

Using turtles as an example

Not all turtles will survive
There is variation within the turtle population (some more suited to environment)
Selective pressures allow turtles with a advantageous genes to survive
Turtles with the advantageous gene pass it on to their offspring
Over generations, the frequency of turtles with the gene will be higher than those without
Note: Selective pressures are always changing so the gene may become advantageous

Wouldn't it already be advantageous, as they survived because they had the gene and were fitter with the ones without the gene? Cheers for the help. Can you explain the founder effect and population bottleneck ?

[Biology24123]

Sorry, meant not advantageous

[cosine]

Sorry, meant not advantageous

Many thanks!

Can you explain population bottlenecks and founder effect? Thanks

[BakedDwarf]

May you give an example of this? What happens to the organisms that are not well suited as the others?

I'll use the example of the peppered moth. Note: I don't know how correct this particular evolution is, however the idea of natural selection is made evident.

1. Before the industrial revolution, the white-bodied peppered moths were dominant and of greater population size than black-bodied peppered moths. They were better suited to their environment because they were able to camouflage in the clean environment and hence remain hidden from predators more effectively than black moths

2. However, after the industrial revolution, the black colour was beneficial in the new polluted environment due to the 'blackened' trees. Therefore, black-bodied peppered moths were able to hide from predators more effectively than white ones

3. Because of the black colour being selected over white, black-peppered moths were more likely to survive, reproduce and pass on their alleles to the next generation than white ones. Gradually, the number of black-bodies peppered moths increased and white-bodied peppered moths decreased

Can you explain the founder effect and population bottleneck ?

Population bottleneck is when a population is severely reduced in size because of a random catastrophic event. That is, even if the population grows again in size, their genetic diversity does not. This reduction of genetic diversity obviously has negative affect towards the survival of the population

The founder effect is when a small unrepresentative group of the original population colonise a new area. Their gene pool is likely to have different allele frequencies when compared to the original population

[cosine]

I'll use the example of the peppered moth. Note: I don't know how correct this particular evolution is, however the idea of natural selection is made evident.

1. Before the industrial revolution, the white-bodied peppered moths were dominant and of greater population size than black-bodied peppered moths. They were better suited to their environment because they were able to camouflage in the clean environment and hence remain hidden from predators more effectively than black moths

2. However, after the industrial revolution, the black colour was beneficial in the new polluted environment due to the 'blackened' trees. Therefore, black-bodied peppered moths were able to hide from predators more effectively than white ones

3. Because of the black colour being selected over white, black-peppered moths were more likely to survive, reproduce and pass on their alleles to the next generation than white ones. Gradually, the number of black-bodies peppered moths increased and white-bodied peppered moths decreased
Population bottleneck is when a population is severely reduced in size because of a random catastrophic event. That is, even if the population grows again in size, their genetic diversity does not. This reduction of genetic diversity obviously has negative affect towards the survival of the population

The founder effect is when a small unrepresentative group of the original population colonise a new area. Their gene pool is likely to have different allele frequencies when compared to the original population

What type of selection would the industrial revolution be? Is this an example of natural selection? (If so, why/why not?)

For population bottleneck, can the event be anything? Also, does this even non-selectively wipe out the population of the species? Is the actual 'population bottleneck' referred to the population that survives the event, or the population that dies because of it?

Thanks for that BakedDwarf and Biology24123, appreciate your help!

[Biology24123]

Founder effect: Loss of genetic variation when a population is started by a very small number of individuals 
Bottleneck effect: Sharp decrease in the population due to environmental effects