VCE Biology Question Thread

[PhoenixxFire]

Is there a difference between B cell receptors and antibodies?

I assume its just a functional difference; antibodies neutralise antigens, whereas B cell receptors recognise antigens.

Yeah it’s just functional. B cell receptors are just antibodies that are embedded in membranes. Note that antibodies also recognise antigens though. Better to say that they allow differentiation/proliferation to occur by binding their complimentary antigen or something like that.

[Owlbird83]

I found that on my mid year exam some questions related to experimental design, which is something that I hadn't revised or payed much attention to. Does anyone know how big of a part this is in the study design? Also are there any resources that can help with those questions?
Thanks

[PopcornTime]

I found that on my mid year exam some questions related to experimental design, which is something that I hadn't revised or payed much attention to. Does anyone know how big of a part this is in the study design? Also are there any resources that can help with those questions?
Thanks

Definitely a big part of the study design! Majority of last year's exam related to experimental design and there was even a 14 mark question (with sub questions) relating to a whole experiment on cell respiration. I suggest reviewing through the general structure of prac reports: aim, hypo, variables, materials, method, results, discussion and conclusion.

[Owlbird83]

Definitely a big part of the study design! Majority of last year's exam related to experimental design and there was even a 14 mark question (with sub questions) relating to a whole experiment on cell respiration. I suggest reviewing through the general structure of prac reports: aim, hypo, variables, materials, method, results, discussion and conclusion.

Thank you!

[PopcornTime]

In what situation would T helper cells activate NK cells instead of cytotoxic T cells?

Also for 2008 Bio exam question 5 b), why can't you talk about the humoral response?

[darkz]

In what situation would T helper cells activate NK cells instead of cytotoxic T cells?

Also for 2008 Bio exam question 5 b), why can't you talk about the humoral response?

I don't believe that T helper cells really interact with NK cells, as NK cells are apart of the innate immune system, but maybe they secrete cytokines that somehow help to stimulate more NK cells? As for the 2008 bio exam, you can't talk about the humoral response because its transplanted tissue - so the cell mediated response should be used. The humoral response is for extracellular pathogens/ antigens e.g. viral particles in the bloodstream or bacteria.

[PopcornTime]

Ok, only because the answers to that question (2008) say that:
• in the cell mediated immune response, T-cell mediated rejection response occurs and T-helper cells activate
cytotoxic T-cells and/or NK (natural killer) cells
• cytotoxic chemicals are produced which destroy foreign cells or macrophages engulf and destroy foreign material.

[PopcornTime]

Why would oxygen be a competitive inhibitor of RuBP carboxylase in the light-independent reactions?

[PopcornTime]

Hypothalamus secretes TRH which stimulates the anterior pituitary to secrete TSH, which induces the thyroid gland to secrete thyroxine.

So, to control the system, would thyroxine act on the gland that produced it, the thyroid gland, or on the hypothalamus?

[nicholas9027]

Hey Guys,
What is the function of Cholesterol in the plasma membrane?
Can i just write : To keep the membrane firm but fluid? or is that too simple (imagine this question was on a vcaa exam)
Thanks in advance

[darkz]

Hey Guys,
What is the function of Cholesterol in the plasma membrane?
Can i just write : To keep the membrane firm but fluid? or is that too simple (imagine this question was on a vcaa exam)
Thanks in advance

Well I'd believe that a question like that would be only one mark, so you could probably keep it pretty brief. Here's what I'd probably write:
Cholesterol helps to maintain the fluidity and stability of the plasma membrane by preventing phospholipid molecules from aggregating in low temperatures and prevents the plasma membrane from disintegrating when temperatures are high

Hypothalamus secretes TRH which stimulates the anterior pituitary to secrete TSH, which induces the thyroid gland to secrete thyroxine.

So, to control the system, would thyroxine act on the gland that produced it, the thyroid gland, or on the hypothalamus?

Well the system works by the negative feedback system. So I looked up a flowchart of it, and it would seem that the thyroid hormones e.g. thyroxine, have a negative feedback on both the hypothalamus and anterior pituitary - although some diagrams only show it having a negative feedback on the anterior pituitary and not the hypothalamus. But nevertheless, therefore, increased thyroxine production would effectively lower the production of TRH and TSH  -> lower levels of thyroxine, to maintain the homeostasis of the body. (The main idea to take out of this I suppose would be that the system is regulated by negative feedback)

Mod edit: merged double post --Calebark

[PopcornTime]

Hey Guys,
What is the function of Cholesterol in the plasma membrane?
Can i just write : To keep the membrane firm but fluid? or is that too simple (imagine this question was on a vcaa exam)
Thanks in advance

That question was in one of the past vcaa exams and the answer they wanted was simple. Think it was just maintain the stability and fluidity of the plasma membrane.

[PhoenixxFire]

Why would oxygen be a competitive inhibitor of RuBP carboxylase in the light-independent reactions?

I don’t know the answer to this, I tried to google it but I couldn’t find anything on it either. Don’t worry about it though - it’s not something that you need to know for VCE.

[Scribe]

What's the difference between clonal selection and clonal expansion?

[TheBigC]

What's the difference between clonal selection and clonal expansion?

I don't intend to be the "sour-mouthed" individual around here, but these types of questions are easily answered with a simple google search... it will be of immense help when, in the future, you need to be proactive and do some of your own research...