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March 19, 2024, 01:08:20 pm

Author Topic: VCE Biology Question Thread  (Read 3563176 times)  Share 

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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #12765 on: July 10, 2020, 04:08:08 pm »
0
Can someone explain epistasis I don’t really understand it

Coolmate

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Re: VCE Biology Question Thread
« Reply #12766 on: July 10, 2020, 04:19:19 pm »
+4
Can someone explain epistasis I don’t really understand it

Hey Chocolatepistachio,

This article/ resource is by "Biology Dictionary" and has the definition of Epistasis, types of epistasis and different kinds of examples to help you understand this concept:
https://biologydictionary.net/epistasis/

Also, this video by "AK LECTURES" explains what Epistasis is with a few examples (skip to 2:50):
https://www.youtube.com/watch?v=XEltUZ0_gDQ

I hope this helps!
Coolmate 8)
« Last Edit: July 10, 2020, 04:25:27 pm by Coolmate »
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1729

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Re: VCE Biology Question Thread
« Reply #12767 on: July 10, 2020, 04:20:33 pm »
+7
Can someone explain epistasis I don’t really understand it
This is definitely a googable question. You need to elaborate on what you don't understand.
But otherwise, I point to you this website. https://courses.lumenlearning.com/wm-biology1/chapter/reading-epistasis-2/

Also I'm pretty sure epistasis is like when one gene suppresses the expression of another or something. Theres different types of epistasis the one pictured is recessive epistasis if im thinking correctly.

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #12768 on: July 10, 2020, 05:16:54 pm »
+1
Ok thanks. Also for this question
Cystic fibrosis is an autosomal recessive trait that affects many parts of the body particularly the lungs and other organs. Parents who show none of the characteristics of cystic fibrosis have an affected child. The chance that there next child will be phenotypically normal is
A three in four
B one in four
C one in two
D zero

Why is the answer for this question A

Sine

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Re: VCE Biology Question Thread
« Reply #12769 on: July 10, 2020, 05:19:45 pm »
+7
Ok thanks. Also for this question
Cystic fibrosis is an autosomal recessive trait that affects many parts of the body particularly the lungs and other organs. Parents who show none of the characteristics of cystic fibrosis have an affected child. The chance that there next child will be phenotypically normal is
A three in four
B one in four
C one in two
D zero

Why is the answer for this question A
If the parents have no characteristics but have an affected child then the parents must be heterozygotes for CF so Aa x Aa

If you do a punnet square of that cross you find that 1/4 will be affected and 3/4 will be phenotypically normal.

1729

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Re: VCE Biology Question Thread
« Reply #12770 on: July 10, 2020, 06:50:29 pm »
+2
Ok thanks. Also for this question
Cystic fibrosis is an autosomal recessive trait that affects many parts of the body particularly the lungs and other organs. Parents who show none of the characteristics of cystic fibrosis have an affected child. The chance that there next child will be phenotypically normal is
A three in four
B one in four
C one in two
D zero

Why is the answer for this question A
Cystic fibrosis is recessive. Let’s just use the letter A to represent genotypes. The parents of the affected child have to have genotypes Aa and Aa, since it says that they show no characteristics of cystic fibrosis but still had an affected child with the genotype aa. So this is a mono hybrid cross. Therefore there’s a 3/4 chance (1 AA, 2 Aa) that the next child will not have cystic fibrosis.

Don't hesitate to question if you need further clarification!

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #12771 on: July 10, 2020, 07:45:35 pm »
0
What’s the difference between a monohybrid and dihbrid cross.

Owlbird83

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Re: VCE Biology Question Thread
« Reply #12772 on: July 10, 2020, 07:51:14 pm »
+7
What’s the difference between a monohybrid and dihbrid cross.
Monohybrid is comparing one trait, dihybrid is comparing two traits. (You'll get a faster response if you google something like that).
A punnet square of a dihybrid cross has 16 boxes to show the different possible genotypes compared to monohybrid that has the four.
« Last Edit: July 10, 2020, 07:52:59 pm by Owlbird83 »
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Re: VCE Biology Question Thread
« Reply #12773 on: July 10, 2020, 10:25:21 pm »
+4
Ok thanks. Also for this question
Cystic fibrosis is an autosomal recessive trait that affects many parts of the body particularly the lungs and other organs. Parents who show none of the characteristics of cystic fibrosis have an affected child. The chance that there next child will be phenotypically normal is
A three in four
B one in four
C one in two
D zero

Why is the answer for this question A
Before I answered this I answered this in a rush but since I’m not in a rush let me actually give you a concise answer.

So CF is an autosomal recessive disease; thus, an individual must express both recessive genes in order to express the diseased phenotype. Individuals who do not express both diseased alleles will be phenotypically normal.

Let F = normal gene and f = CF gene. Individuals who express FF or Ff genotypes will not have CF, but they will have CF if they have the ff genotype because the gene is autosomal recessive.

Father genotype = Ff
Mother genotype = Ff

The parents must have the Ff genotype because the question stem indicates that they do not show the characteristics of CF but do have an affected child. This finding indicates that the parents must be carriers of the CF gene, as carriers are phenotypically normal but are capable of producing children with the diseased phenotype.

Next, create a Punnett square to determine the potential genotypes of the offspring:
Ff × Ff = FF + 2Ff + ff

Thus, there is a 1/4 = 25% probability that the parents will have a child with CF; the Punnett square shows that 1/4 of the children have the ff genotype. In contrast, there is a 3/4 = 75% chance that the parents will have a phenotypically normal child (3/4 do NOT have the ff genotype).

homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12774 on: July 11, 2020, 11:50:54 am »
+1
Hello! I am using the edrolo textbook and under 'gene cloning' the textbook vaguely goes over viral vectors. I don't really understand how they use the viral vectors to insert DNA into a host. How do they use the vector to do that, and are viral vectors important for this aos?
Also, how much do I need to know about Roundup Ready plants and Bt crops?
« Last Edit: July 11, 2020, 12:56:22 pm by homeworkisapotato »
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Owlbird83

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Re: VCE Biology Question Thread
« Reply #12775 on: July 11, 2020, 04:05:30 pm »
+7
Hello! I am using the edrolo textbook and under 'gene cloning' the textbook vaguely goes over viral vectors. I don't really understand how they use the viral vectors to insert DNA into a host. How do they use the vector to do that, and are viral vectors important for this aos?
Also, how much do I need to know about Roundup Ready plants and Bt crops?
They modify the virus's DNA by adding a healthy gene that the person with the gene needs. The virus then can be put into the person, then in the body it can enter cells and inject the healthy DNA into the nucleus. The healthy gene is then transcribed and translated by the person's cells to create functioning proteins. ( it's used for when a person has a disease caused by a faulty gene that creates faulty proteins). Viruses normally infect cells by injecting them with it's own viral DNA, but in this method they are modified and used as vehicles for our advantage.
Viral vectors aren't specifically mentioned in the study design, so I don't think you need to know any more than what I've written.

You wouldn't need to know information specific to roundup ready plants or bt crops, but I think it's good to  know what they are because they might pop up and are good examples of genetic modification and to help you understand how and why they modify crops. It's important to know info that broadly deals with genetically modified organisms/crops and the positive and negative implications and how they are used.
Except from the SD: 'the distinction between genetically modified and transgenic organisms, their use in agriculture to increase crop
productivity and to provide resistance to insect predation and/or disease, and the biological, social and ethical
implications that are raised by their use
'

Hope that helps :)
« Last Edit: July 11, 2020, 04:07:24 pm by Owlbird83 »
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12776 on: July 12, 2020, 07:04:06 pm »
+2
They modify the virus's DNA by adding a healthy gene that the person with the gene needs. The virus then can be put into the person, then in the body it can enter cells and inject the healthy DNA into the nucleus. The healthy gene is then transcribed and translated by the person's cells to create functioning proteins. ( it's used for when a person has a disease caused by a faulty gene that creates faulty proteins). Viruses normally infect cells by injecting them with it's own viral DNA, but in this method they are modified and used as vehicles for our advantage.
Viral vectors aren't specifically mentioned in the study design, so I don't think you need to know any more than what I've written.

You wouldn't need to know information specific to roundup ready plants or bt crops, but I think it's good to  know what they are because they might pop up and are good examples of genetic modification and to help you understand how and why they modify crops. It's important to know info that broadly deals with genetically modified organisms/crops and the positive and negative implications and how they are used.
Except from the SD: 'the distinction between genetically modified and transgenic organisms, their use in agriculture to increase crop
productivity and to provide resistance to insect predation and/or disease, and the biological, social and ethical
implications that are raised by their use
'

Hope that helps :)
Thank you so much for your clarification!! Do i need to know the temperatures for the steps of polymerase chain reaction?
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Sine

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Re: VCE Biology Question Thread
« Reply #12777 on: July 12, 2020, 07:07:03 pm »
+2
Thank you so much for your clarification!! Do i need to know the temperatures for the steps of polymerase chain reaction?
yep the temperatures for PCR are vital

homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12778 on: July 12, 2020, 07:18:34 pm »
0
yep the temperatures for PCR are vital
Thank you!
Different sources say different numbers:
Edrolo says 90-95, 50-55, 72
AN notes say 94, 55, 72
My teacher's powerpoint says: 95, 50-55, 72
Which one should I follow?
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Re: VCE Biology Question Thread
« Reply #12779 on: July 12, 2020, 07:25:05 pm »
+4
Thank you!
Different sources say different numbers:
Edrolo says 90-95, 50-55, 72
AN notes say 94, 55, 72
My teacher's powerpoint says: 95, 50-55, 72
Which one should I follow?
You should get marks for all of them.

In 2012 VCAA's answer to a description of PCR was the following though.

Quote
heat DNA to approximately 90 °C or to separate strands
cool to approximately 50 °C or to anneal/attach primers
heat to approx 72 °C or Taq/DNA polymerase copies strands
repeat cycle.:

https://www.vcaa.vic.edu.au/Documents/exams/biology/2012/Biology_assessrep_12.pdf