Biology Unit 3 Questions Megathread

[scocliffe09]

They are primary hosts and (I'm pretty sure) they are also vectors. "Host" status doesn't mean they have to be harmed, this can be seen in mutually beneficial relationships.

When we talk about primary and secondary hosts we are often referring to parasitic lifecycles - because they are often in different forms throughout that cycle.
Mosquitoes are vectors - they help transfer the plasmodium (protozoan) - but, as Lex said, they are also the primary host, because that's where the protist matures.

[Kaille]

am i right in saying that little development occurs in the intermediate host?

[lexitu]

Yep generally that's correct because the parasite usually spends less time in the intermediate host although as Eddie (scocliffe09) mentioned the main thing that defines a host as primary or secondary/intermediate is whether the parasite matures while being hosted by them.

[Drunk]

apparently the answer's B
whaaaattt

[jane1234]

(Image removed from quote.)

apparently the answer's B
whaaaattt

N is the only one that doesn't have antigens complementary to any of the antibodies already present in her body. Therefore no antibodies are present in her body that can recognise the bacterium. This means it will take longer to kill the virus, resulting in a more severe infection.

[Drunk]

OHHHHH that totally makes sense
Thanks!

[WhoTookMyUsername]

Neap says the proteome is the complete array of proteins in a cell produced in its lifetime

i thought proteome was under specific conditions at a specific time, and wiki (best source i know :|) confirms this

can anyone else?  thanks



EDIT :

Do non - pathogenic material e.g. toxin, nicotine usually just small fragements that are completely bound by the variable region of an antibody (e.g. 1 binding site is fully occuped by 1 fragment, fragment cannot bond to otther antibodies) or is it more like a bacterium, where the antigens are on the outside of a circular shaped fragment?

[scocliffe09]

Neap says the proteome is the complete array of proteins in a cell produced in its lifetime

i thought proteome was under specific conditions at a specific time, and wiki (best source i know :|) confirms this

can anyone else?  thanks



EDIT :

Do non - pathogenic material e.g. toxin, nicotine usually just small fragements that are completely bound by the variable region of an antibody (e.g. 1 binding site is fully occuped by 1 fragment, fragment cannot bond to otther antibodies) or is it more like a bacterium, where the antigens are on the outside of a circular shaped fragment?

The proteome is normally under specific conditions / at a specific time in the cell's life cycle, but I don't see why you couldn't define it as being of a cell's entire life. It's often used to analyse the gene expression of a cell.
The other question, I can assure you, is far beyond what you'll need to know for VCE - I don't quite know what your question is either. I think you need to be careful not to rely on simplified diagrams too much and remember that everything, such as antigen-toxin binding, is far more complex than VCE will tell you. That said, as far as I know, other material released by pathogens is bound by antibodies, and I don't see why more than one ab couldn't bind to it if there were more binding sites.

[WhoTookMyUsername]

thanks scocliffe

yeah i don't really know how to expalin the second question without  diagram well, just in one of the NEAP exams, we had to draw nictotine binding to an antibody, and i drew the nicotine as more resembling a bacterium instead of just a small fragment that is enclosed fully by one actibody binding sites

in VCE level, should i draw toxins resembling the basic shape of a bacterium, with antigens on its surface, or just small fragments (e.g. 1 triangle representing 1 nictoine molecule?) thanks

[Russ]

I never considered proteome = at a single time, I always likened it to genome, to be the total protein complement of the cell.

A toxin may have multiple binding sites (epitopes), so there's nothing to say it can't be bound by multiple Ab at any one time. Protein toxins are generally quite large relative to other (lipid) toxins, so they have a relatively large amount of conformational determinants.

I wouldn't draw toxins resembling a bacterium because they're not cells. I'd draw a squiggly line then an antibody with an Fab specific for one part of my line

[amun]

Describe how ATP acts as a supplier of energy to power metabolic reactions ?

[Kaille]

Describe how ATP acts as a supplier of energy to power metabolic reactions ?

The enzyme ATPase causes ATP to be hydrolysed to produce ADP and a free phosphate, thus releasing stored potential energy in the process.

[jane1234]

1. Do histamines cause fever as part of the inflammatory repsonse?

2. Attached below.
I said D because they look like channels to me, but the answers say B.

[Drunk]

its because the neurotransmitter needs a receptor to trigger a response in the next nerve cell, and I'm pretty sure neurons don't have receptors for neurotransmitters inside the cells themselves

[jane1234]

its because the neurotransmitter needs a receptor to trigger a response in the next nerve cell, and I'm pretty sure neurons don't have receptors for neurotransmitters inside the cells themselves

Yeah but they bind to a receptor in order to open the channels which are also on the postsynaptic membrane... and it looked like a channel to me :S