VCE Biology Question Thread

[geminii]

C'mon, do some research before asking these questions. This forum is designed so that people can clarify elements of the course they're not sure about and discuss what they're doing in Biol at the moment, not so people can do your homework for you.

Wow, I was just asking.
I searched on the internet but there are some websites that say different things from others. One website said that some parasites are prokaryotic while others are eukaryotic, but I wasn't sure if in VCE they should be classified as both, or one or the other. As we know, some things are not within the scope of what we need to learn in VCE. That's why I asked.

[pi]

Wow, I was just asking.
I searched on the internet but there are some websites that say different things from others. One website said that some parasites are prokaryotic while others are eukaryotic, but I wasn't sure if in VCE they should be classified as both, or one or the other. As we know, some things are not within the scope of what we need to learn in VCE. That's why I asked.

Sounds harsh, but I'm with Mr. T-Rav on this one. The best one can use AN is by doing some work themselves, and asking for clarifications, that's how one can learn the most. So how about you tell us what you think the answers to those q's are and then someone will point out where you might be mistaken

[vox nihili]

Wow, I was just asking.
I searched on the internet but there are some websites that say different things from others. One website said that some parasites are prokaryotic while others are eukaryotic, but I wasn't sure if in VCE they should be classified as both, or one or the other. As we know, some things are not within the scope of what we need to learn in VCE. That's why I asked.

Sorry if that came across as too harsh. pi put it really well (as always). You do yourselves a disservice if you immediately skip to asking questions on the forum rather than doing some of your own research. Believe me, anything you find out on your own is something you're much more likely to remember than any answers you get here.
If you can't find the answer reasonably easily, however, tell us about what you've read and what you think the answer might be so that people can clarify for you. The last thing we want to do is discourage you from participating

[Gogo14]

1.can you define pathogens as being parasites that  cause disease?
2. How do prions infect and cause disease?
Is it by signal transduction into the cell, causing somethijng to change, hence affecting the function of the cell?
3. Why and how is genetics related to susceptability to some diseases? E.g. Acne

[vox nihili]

1.can you define pathogens as being parasites that  cause disease?
2. How do prions infect and cause disease?
Is it by signal transduction into the cell, causing somethijng to change, hence affecting the function of the cell?
3. Why and how is genetics related to susceptability to some diseases? E.g. Acne

1. Infectious agents that cause disease is probably a better definition*
2. You don't need to know. Prions are actually proteins normally found in the brain. The infectious prions, however, are misfolded versions of these prions. When the nasty prions get in, they induce misfolding of the other prions and basically what happens is they clump altogether and get inthe way of things—they basically just replace normal brain tissue.
3. Why do you think? (genuinely asking for an answer here—have a guess first!)


*for the pedants out there: yes, I understand this isn't correct but it is correct in the context of VCE

[cosine]

Hey everyone! It would be awesome if someone could tell me:
- Which ones of: parasites, prions, viruses, and bacteria are prokaryotic or eukaryotic.
- How each of these, as well as protozoans and fungi, infect host cells
- The structure of parasites, prions, viruses, bacteria, fungi and protozoans
- How different types of each group can be identified (for example, for bacteria, you can use the gram stain test)


Thanks SO much!!!

1. Prions and viruses are non-cellular agents, hence do not fall in either prokaryotes nor eukaryotes. Parasites are eukaryotes since they are multicellular and bacteria are prokaryotes, since they are unicellular.

2. In the context of VCE, bacterial cells dont necessarily enter cells to infect them (however in real life, some do). Bacterial cells multiply via binary fission very rapidly, you dont need to know 'how' they infect, but keep in mind they do not themselves enter host cells, hence they must secrete something else that will do the damage. Viruses have two modes of infection, by entering the cell completely or by just attaching themselves on a cell's membrane and injecting their viral components (DNA or RNA). When the virus enters a cell, they invade the host mechanisms to reproduce and the cell will undergo lysis due to an abundant reproduction of viral components, or sometimes the viruses replicated will remain in the cell dormant until they receive a stimulus to leave. When the virus injects DNA or RNA into the host cell, this nucleic acid will be transcripted and translated into new viral components, and then be arranged into cloned viruses. Protozoans and fungi - no idea

3.
Structure of parasites: multicellular 'worms'. Typically larger than the other pathogenic agents
structure of fungi: some fungi are multicellular, some are unicellular (yeast).
structure of bacteria: unicellular cells with capsule, outer membrane, cell wall, inner membrane and plasma membrane. (not all bacterial cells have all of those walls/membranes).
structure of viruses: protein coated nucleic acid, either DNA or RNA, not both.
structure of prions: deformed protein molecules that are pathogenic
structure of protozoans: unicellular but eukaryotic organisms

4. This is too specific of a question, do not worry about this in VCE level. However there are two main types of bacteria, gram positive and gram negative. Gram positive have only a cell wall and plasma membrane, whereas gram negative have an outer membrane, plasma membrane and a cell wall. Viruses, to determine whether they are DNA or RNA you would have to use radioactive labelling. Also RNA based viruses are known as retroviruses. As for prions, we said they are deformed protein molecules that cause infections/disease, so you can obviously compare the molecular shape to a normally functioning protein, but this is just an assumption and not sure if its an actual method used by scientists.

[geminii]

1. Prions and viruses are non-cellular agents, hence do not fall in either prokaryotes nor eukaryotes. Parasites are eukaryotes since they are multicellular and bacteria are prokaryotes, since they are unicellular.

2. In the context of VCE, bacterial cells dont necessarily enter cells to infect them (however in real life, some do). Bacterial cells multiply via binary fission very rapidly, you dont need to know 'how' they infect, but keep in mind they do not themselves enter host cells, hence they must secrete something else that will do the damage. Viruses have two modes of infection, by entering the cell completely or by just attaching themselves on a cell's membrane and injecting their viral components (DNA or RNA). When the virus enters a cell, they invade the host mechanisms to reproduce and the cell will undergo lysis due to an abundant reproduction of viral components, or sometimes the viruses replicated will remain in the cell dormant until they receive a stimulus to leave. When the virus injects DNA or RNA into the host cell, this nucleic acid will be transcripted and translated into new viral components, and then be arranged into cloned viruses. Protozoans and fungi - no idea

3.
Structure of parasites: multicellular 'worms'. Typically larger than the other pathogenic agents
structure of fungi: some fungi are multicellular, some are unicellular (yeast).
structure of bacteria: unicellular cells with capsule, outer membrane, cell wall, inner membrane and plasma membrane. (not all bacterial cells have all of those walls/membranes).
structure of viruses: protein coated nucleic acid, either DNA or RNA, not both.
structure of prions: deformed protein molecules that are pathogenic
structure of protozoans: unicellular but eukaryotic organisms

4. This is too specific of a question, do not worry about this in VCE level. However there are two main types of bacteria, gram positive and gram negative. Gram positive have only a cell wall and plasma membrane, whereas gram negative have an outer membrane, plasma membrane and a cell wall. Viruses, to determine whether they are DNA or RNA you would have to use radioactive labelling. Also RNA based viruses are known as retroviruses. As for prions, we said they are deformed protein molecules that cause infections/disease, so you can obviously compare the molecular shape to a normally functioning protein, but this is just an assumption and not sure if its an actual method used by scientists.

Thank you SO much cosine! This truly helped a lot!
The information I found on the internet was either at too basic of a level or at a higher level of knowledge.

Thanks again!

[plsbegentle]

Where is everyone up to in class? Finish immunity or just started??!

[vox nihili]

Where is everyone up to in class? Finish immunity or just started??!

Students I'm working with seem to be just starting immunity or just about to.

[cosine]

Thank you SO much cosine! This truly helped a lot!
The information I found on the internet was either at too basic of a level or at a higher level of knowledge.

Thanks again!

Glad I could help. Just for my own improvement, was my help in the middle of the difficulty? Is there enough info or is there too much? Thanks

[geminii]

Glad I could help. Just for my own improvement, was my help in the middle of the difficulty? Is there enough info or is there too much? Thanks

It was just right, the difficulty was about the same as what we're doing now. There's a good amount of info too, thanks.

[gameboy99]

Hi guys,
Do you think I should learn diseases that are associated with each of the pathogens learnt in immunity as we have done this at school and there is a lot of diseases to learn(e.g Mad cow's disease, Gential herpes, Black plaque, Athletes Foot, Worms, Malaria .....other diseases caused by bacteria such as Diptheria, Food poisoning, Tetanus, Pneumonia, Tuberculosis, Meningitis)

Does any past students recommend me to learn many diseases like the examples given above if I am aiming for a 50?

[thefrog]

Hi! Just wondering if someone could help clarify a few things:

1. Do B/T cells have MHC class I markers as well as class II markers? My teacher said they only have class II markers :/
2. How do B cells become APCs? Do they, like phagocytes, engulf the pathogen and present the antigens etc.?
3. Why must antigen presentation occur for T-helper cells to stimulate other B/T cells?

Thank-you in advance!

[vox nihili]

Hi! Just wondering if someone could help clarify a few things:

1. Do B/T cells have MHC class I markers as well as class II markers? My teacher said they only have class II markers :/
2. How do B cells become APCs? Do they, like phagocytes, engulf the pathogen and present the antigens etc.?
3. Why must antigen presentation occur for T-helper cells to stimulate other B/T cells?

Thank-you in advance!

1. They have both.
2. That's correct, although you don't need to know that for VCE
3. Because T-cell receptors can only bind to antigen in the context of MHC molecules. In essence it just comes down to the structure of their receptors. There are actually some advantages to doing things this way, but that's beyond VCE once again.

Hi guys,
Do you think I should learn diseases that are associated with each of the pathogens learnt in immunity as we have done this at school and there is a lot of diseases to learn(e.g Mad cow's disease, Gential herpes, Black plaque, Athletes Foot, Worms, Malaria .....other diseases caused by bacteria such as Diptheria, Food poisoning, Tetanus, Pneumonia, Tuberculosis, Meningitis)

Does any past students recommend me to learn many diseases like the examples given above if I am aiming for a 50?

It's always handy to have a couple of examples for each (with the exception of prions and especially for bacteria and viruses), but knowing the ins and outs of these diseases is not necessary.

[HasibA]

question -> in vce, are we allowed to use dot points to explain short answer questions in the sciences, specifically bio,chem , or psych?
i'd assume so, but i've heard conflicting info, and don't want to be penalised unnecessarily! thank you.