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March 29, 2024, 09:37:35 am

Author Topic: VCE Biology Question Thread  (Read 3571023 times)  Share 

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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9360 on: October 04, 2017, 09:23:18 am »
+3
DNA profiling is used as a unique identifier of a person - like a fingerprint. It can be used to determine who a criminal is when DNA was found at a crime scene. It can also be used to determine relatedness between people (because DNA is inherited), eg. paternity testing.

Genetic screening is a test to determine whether an individual has a disease causing allele.

As they both involve a person genetic information, there will be some that apply to both.
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rainbowsparkles15

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Re: VCE Biology Question Thread
« Reply #9361 on: October 04, 2017, 01:14:55 pm »
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How are GMOs and transgenic organisms used in agriculture to increase crop productivity and to provide resistance to insect predation and/or disease?

Also, how do we identify pathogens?

EDIT: Added a question
« Last Edit: October 04, 2017, 01:35:05 pm by rainbowsparkles15 »
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LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9362 on: October 04, 2017, 01:51:56 pm »
+6
How are GMOs and transgenic organisms used in agriculture to increase crop productivity and to provide resistance to insect predation and/or disease?

Also, how do we identify pathogens?

EDIT: Added a question

GMOs and trangenic organisms (transgene is a type of genetic modification) are organisms which contain genetic material from other sources (usually organisms of other species, which makes a GMO a transgenic organism). For plants, this could mean that one can modify a specific section of a gene within the plant to increase its crop yield, which in turn increases their crop productivity in agriculture. Sections of genes which codes for resistance towards pests, weeds and microbes can also be inserted within the genome of an organism (these genes may be expressed and a protein or toxin could be produced to fend off these pests, weeds and microbes).

There are actually a few ways to identify a pathogen (bacteria or virus, in this case)
Bacteria:
- agglutination test (with specific antibodies)
- precipitation test (to see if a bacterial colony precipitates in the blood of an infected person)
- Western blot test (used to separate and identify proteins specific to a bacteria)
- ELISA (enzyme-linked immunosorbent assay, which is used to detect and count substances such as antibodies, hormones, enzymes and antigens, which indicates the type of bacteria we might be looking for)
Virus (these things are smaller, so we have to use more precise techniques to kinda sort them out)
- ELISA
- X-ray crystallography (which is used to determine the atomic and molecular structure of crystals, can be used to identify viruses of specific shapes and sizes)
- Electron microscope (these things let you see really small things so you can see viruses with this)
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9363 on: October 04, 2017, 01:56:07 pm »
+4
LifeisaConstantStruggle beat me to it whilst i was typing but i will add this,

There are two main ways that insect predation is stopped. They are given a gene that makes them resistant to insecticide/herbicide, they can then be sprayed a lot, killing the pests but not the plant. Or they produce a protein (eg. Bollard cotton) so that, when an insect eats the plant, the protein will kill them.

Also worth noting that genetic technology can be used to identify a crop's genotype - deciding which should be used in the next generation, which is more accurate than relying on phenotypic characteristics (ie. normal selective breeding). This is used a lot, especially with cattle for milk production but these organism have not been altered so they are not GMO's.
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LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9364 on: October 04, 2017, 02:16:40 pm »
+2
 
Also worth noting that genetic technology can be used to identify a crop's genotype - deciding which should be used in the next generation, which is more accurate than relying on phenotypic characteristics (ie. normal selective breeding). This is used a lot, especially with cattle for milk production but these organism have not been altered so they are not GMO's.

This is some great insight on this topic! :)

Also, on GMOs which have resistance against certain diseases/pests, *this can also be a positive social implication* pest resistant crops can help save farmers and governments heaps of money as they no longer require insecticides or herbicides which can cost a lot of money, and pollute the environment, resulting in a lower cost to produce crops, and consumers can purchase these crops at cheaper prices as well.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9365 on: October 04, 2017, 02:43:15 pm »
0
If someone had an immune disease and they produced plasma cells but not memory cells would that be active or passive immunity? And is that actually possible?
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LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9366 on: October 04, 2017, 03:16:42 pm »
+2
I don't think that's actually possible (at least in the VCE context) because plasma cells are produced alongside memory B cells during clonal selection and expansion. Memory cells are essentially B cells that have not become plasma cells, and they go through the same process during a humoral response to become plasma cells. For these types of cells diseases are often all or nothing (which means that you either have no B or T cells of the adaptive immune system or you have all of it. Eg: SCID, or severe combined immunodeficiency, where the body does not have any adaptive immune cells)
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9367 on: October 04, 2017, 03:26:16 pm »
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Yeah I figured it wasn't really relevant, just satisfying my curiosity :) I asked because people with AIDS get really sick due to their Th cells being infected, but they don't always die from these illnesses (although they are more likely to) which means either their immune system defeated it or medicine did. Also if their immune system defeated it then they should have memory cells that would defend them against it if they got it again but that doesn't seem to happen. Thanks for the answer!
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LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9368 on: October 04, 2017, 04:10:03 pm »
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Yeah haha, but for AIDs it's due to their lack of Th cells that affect the immune system itself, as Th cells secrete cytokines which initiates the humoral and cell mediated immune response, that's why even though there might be memory cells against a specific disease, they are not activated to undergo clonal expansion.
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K888

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Re: VCE Biology Question Thread
« Reply #9369 on: October 04, 2017, 04:24:03 pm »
+3
Yeah I figured it wasn't really relevant, just satisfying my curiosity :) I asked because people with AIDS get really sick due to their Th cells being infected, but they don't always die from these illnesses (although they are more likely to) which means either their immune system defeated it or medicine did. Also if their immune system defeated it then they should have memory cells that would defend them against it if they got it again but that doesn't seem to happen. Thanks for the answer!
If you're interested, my understanding of it is (I could be wrong here, someone please correct if I am):
(Preface: it's important to know the relationship between HIV and AIDS, as obviously there's a progression)
- HIV depletes mature helper T cells (aka CD4 T cells iirc) --> leads to AIDS (acquired immunodeficiency syndrome), which is like, the last stage sort of thing - it's not that their helper T cells are infected, it's that they actually just don't have them
- Immune responses to certain antigens decline, as a result - I think specifically, it's usually non-bacterial ones first - so viral, fungal, etc. (not sure on this one)
- It's classified as AIDS when you start getting significant opportunistic infections/neoplasms (technically, I believe you enter this classification when the concentration of CD4 T cells goes below 200 cells/µl)
- They try to help immune system function with antiretroviral therapies (to basically try to suppress the human immunodeficiency virus), use prophylactic therapies to try prevent opportunistic infections, and treat infections ASAP

If you're curious, I'd recommend having a read about it :)
« Last Edit: October 04, 2017, 06:22:17 pm by K888 »

vox nihili

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Re: VCE Biology Question Thread
« Reply #9370 on: October 04, 2017, 06:12:56 pm »
+3
If someone had an immune disease and they produced plasma cells but not memory cells would that be active or passive immunity? And is that actually possible?

No. This wouldn't happen. Remember the difference between autoimmune and diseases affecting the immune system. Something like MS for instance, involves the immune system effectively attacking the body. AIDS, on the other hand, refers to the depletion of T-cells secondary to their infection by HIV.

Definitely out of the scope of VCE, but if you're interested, my understanding of it is (I could be wrong here, someone please correct if I am):
(Preface: it's important to know the relationship between HIV and AIDS, as obviously there's a progression)
- HIV depletes mature helper T cells (aka CD4 T cells iirc) --> leads to AIDS (acquired immunodeficiency syndrome), which is like, the last stage sort of thing - it's not that their helper T cells are infected, it's that they actually just don't have them
- Immune responses to certain antigens decline, as a result - I think specifically, it's usually non-bacterial ones first - so viral, fungal, etc. (not sure on this one)
- It's classified as AIDS when you start getting significant opportunistic infections/neoplasms (technically, I believe you enter this classification when the concentration of CD4 T cells goes below 200 cells/µl)
- They try to help immune system function with antiretroviral therapies (to basically try to suppress the human immunodeficiency virus), use prophylactic therapies to try prevent opportunistic infections, and treat infections ASAP

If you're curious, I'd recommend having a read about it :)

This is all correct :) (and nearly all of it is now relevant to the VCE course).
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K888

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Re: VCE Biology Question Thread
« Reply #9371 on: October 04, 2017, 06:21:36 pm »
+1
This is all correct :) (and nearly all of it is now relevant to the VCE course).
Well, shows how up to date I am with the new study design lol. Will edit my post.

Cheers for the clarification, vox!

ezferns

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Re: VCE Biology Question Thread
« Reply #9372 on: October 04, 2017, 08:11:33 pm »
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Do carrier proteins used in facilitated diffusion ever use energy? I thought they were always passive?

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9373 on: October 04, 2017, 08:21:49 pm »
+3
Carrier proteins in facilitated diffusion are passive, carrier proteins in active transport require energy
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ardria

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Re: VCE Biology Question Thread
« Reply #9374 on: October 04, 2017, 09:31:16 pm »
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I can't seem to find clear answers to these anywhere, help is very much appreciated :)

1. What effect does pH have on plasma membranes, and why?

2. Why doesn't alcohol have any effect on the plasma membrane?