VCE Biology Question Thread

[cosine]

change the genome of plants for example by inserting genetic material into the plants chromosome.

How so? o.O

[Bruzzix]

How so? o.O

A special type of plasmid called an episome can do it but I have no idea how.

[cosine]

A special type of plasmid called an episome can do it but I have no idea how.

Are we required to know this episome for vce bio?
Or should we be aware that some plasmids can incorporate their genome into the host cell's genome?
This also answers a question i posted earlier in which was left unanswered, I was asking about how GM plants fertilised non-GM plants and why this would raise concerns, was wondering how plasmids could affect the fertilisation, which came from a VCAA exam, so I guess it's a good idea to keep in mind that some plasmids are capable of inserting their genes into the genome of the host?

[vox nihili]

The answer was D. Recessive epistasis. Can you explain why?

Their answer is wrong. Recessive or dominant epistasis is correct. Not going to go into the details of it though, because it's certainly not VCE Biology. Very basically though, epistasis describes a gene interaction, such that the presence of certain alleles modulates the phenotype produced by other alleles.

Are we required to know this episome for vce bio?
Or should we be aware that some plasmids can incorporate their genome into the host cell's genome?
This also answers a question i posted earlier in which was left unanswered, I was asking about how GM plants fertilised non-GM plants and why this would raise concerns, was wondering how plasmids could affect the fertilisation, which came from a VCAA exam, so I guess it's a good idea to keep in mind that some plasmids are capable of inserting their genes into the genome of the host?

Plasmids very often can be used to insert genes into the chromosomal DNA. Indeed, this can occur in bacteria, plants and even human cells.

[Bruzzix]

Are we required to know this episome for vce bio?
Or should we be aware that some plasmids can incorporate their genome into the host cell's genome?
This also answers a question i posted earlier in which was left unanswered, I was asking about how GM plants fertilised non-GM plants and why this would raise concerns, was wondering how plasmids could affect the fertilisation, which came from a VCAA exam, so I guess it's a good idea to keep in mind that some plasmids are capable of inserting their genes into the genome of the host?

Episomes are outside of the study design but you should be aware that some plasmids can integrate genetic material into an organisms chromosomes.
I think I answered that question before?

4. A particular specific of crop was genetically engineered to contain this gene. Such plants are referred to as GM (Genetically Modified). Explain why a farmer might choose to grow a crop that was genetically engineered to be resistant to insects, rather than spray the crop with insecticide?

I said because the growing GM crops, the future generations of the crop will also be able to be resistant to the insecticide, and so the farmer has less worries about his crops.

My query is, Can GM plants replicate their plasmids and pass it down to offspring? I know bacteria can, but can also plant cells do this? Because the following question is an experiment about the pollen of the GM plants fertilising the non-GM plants.

OK there are some problems here. GM plants DO NOT have plasmids!   We insert the gene of interest into a plasmid then mix the modified bacteria with plant cells such as cut up pieces of leaf or stem. Some plant cells uptake the plasmid and the desired gene(s) are inserted into one of the plants chromosomes. We don't need to worry about what happens to the plasmid thereafter but it definitely doesn't have an effect on the plant on its own. The plants now have a permanently modified genome so the offspring will inherit the modified chromosome.
Also I think better answers to the question include: saves money, saves time, removes risk of consumer being harmed form insecticide residue, reduces potential environmental damage from crop/agricultural runoff.

[grindr]

I'm sorry if this question has already been asked but how much do we REALLY need to know about VCE stem cells?

My teacher barely went over this... 

[Biology24123]

I'm sorry if this question has already been asked but how much do we REALLY need to know about VCE stem cells?

My teacher barely went over this... 

Uses of stem cells
What are adult and embryonic stem cells

[warya]

I'm sorry if this question has already been asked but how much do we REALLY need to know about VCE stem cells?

My teacher barely went over this... 

I was like this a while ago, I read through some notes from the notes section and it cleared it up pretty quick, just search up unit 4 biology revision, or look through your textbook

[The Peasant]

I'm sorry if this question has already been asked but how much do we REALLY need to know about VCE stem cells?

My teacher barely went over this... 

The aforementioned, so:

1. Uses of stem cells
2. Types of stem cells and their properties (e.g Embryonic stem cells are pluripotent, Adult stem cells are multipotent etc)
3. The ethical issues surrounding the use of stem cells.

Also, you will most likely need to know the processes and their differences.
1. SCNT(Somatic cell nuclear transfer)
2. iPS (Induced pluripotent stem cell)

So essentially, just a quick summary:
Stem cells are undifferentiated cells (meaning that they do not have specialized roles), hence they can differentiate into specialized cells (e.g heart cells, B cells etc.) when required. There are a variety of stem cells - the type most focused on in this topic would be embryonic stem cells.  The main use of stem cells (by humans) is for therapeutic cloning; this refers to the process by which specialised cells are produced from embryonic stem cells, by inducing/stimulating them to differentiate and proliferate into specific cells to treat diseases and damaged cells of an affected individual. These cells are cultured in vitro, meaning that various chemicals/techniques can be used to achieve the desired cell types.

If you want we to further elab on any of the points made above, I'm happy to do so.

[Elizawei]

Hello, just stumbled upon this amazing world of ATARnotes (my first post )
When a question asks for the diploid number of an organism, do we write the number itself or do we have to say "2n = __"
e.g the diploid number for a normal human. Is the answer "46" or "2n = 46"?

Thanks :3

[Biology24123]

Hello, just stumbled upon this amazing world of ATARnotes (my first post )
When a question asks for the diploid number of an organism, do we write the number itself or do we have to say "2n = __"
e.g the diploid number for a normal human. Is the answer "46" or "2n = 46"?

Thanks :3

Either is fine.

[Biology24123]

Can someone give a exam answer for why hybrids are infertile (2 marks)
I know it's do with the pairing of homologous chromosomes but can't express it well. Thanks

[CarterGray12]

Can someone give a exam answer for why hybrids are infertile (2 marks)
I know it's do with the pairing of homologous chromosomes but can't express it well. Thanks

Hybrids do not have homologous chromosomes which must pair in meiosis during metaphase 1 for meiosis to be completed and for gametes to be produced, hence hybrids are infertile.

[Biology24123]

Hybrids do not have homologous chromosomes which must pair in meiosis during metaphase 1 for meiosis to be completed and for gametes to be produced, hence hybrids are infertile.

Thanks. I think they pair in prophase though

[vox nihili]

Hybrids do not have homologous chromosomes which must pair in meiosis during metaphase 1 for meiosis to be completed and for gametes to be produced, hence hybrids are infertile.

Thanks. I think they pair in prophase though

Correct, prophase it is. A lot of books don't show this particularly well. In meiosis, something called the synaptonemal complex brings the chromosomes together. It forms during prophase. (This last bit is well beyond VCE).