VCE Biology Question Thread

[RazzMeTazz]

How early should you aim to finish the exam so you can check over answers?

[RazzMeTazz]

Thank you! 
The allergen just kinda binds to two IgE antibodies which makes the mast cells release histamine (the process of releasing the histamine is termed as degranulation)

Thanks for this :')

Oh so the term 'cross-linkage' refers specifically to the allergen binding to two IgE antibodies, as opposed to just one?

[althepal]

Also, does the 9:3:3:1 ratio indicate linkage or no linkage between genes?

No linkage. Variation from that indicates linkage. You can't really have an expected ratio for linkage because it's a random event

[RazzMeTazz]

I have two questions:

1.) On the 2013 VCAA exam for Q.11 of short answer the answer for the significance of the wider pelvic girdle in A.africanus as opposed to H.neanderthalensis is "it is harder to walk upright as it tips towards the centre of gravity."

I don't really understand the whole tipping towards the centre of gravity thing?

2.) Should we never make definite statements such as: " Homo Sapiens evolved from Homo Erectus" etc. as all these ideas about human evolution are essentially still just theories, and not facts?

[shivaji]

can discontinuous variation be the result of 2 or more genes as well?

[AllG_]

can discontinuous variation be the result of 2 or more genes as well?

At VCE level, monogenic inheritance = discontinuous and polygenic inheritance = continuous. Don't think we need to know about any exceptions.

Is cilia and mucous a chemical or mechanical barrier?

[Rachelle]

Chitin is said to have an 'N-containing group' attached; does it mean it has nitrogen in its structure?
I though that carbohydrates contained the elements of carbon, oxygen and hydrogen only?

[AllG_]

Chitin does contain nitrogen. It is an exception to the carbohydrates as it contains C, H, O and N whereas most carbs only contain C H O.

[shivaji]

Is cilia and mucous a chemical or mechanical barrier?

mechanical:)

I don't quite understand what the role of cilia and mucous is, and where abouts they operate and how they aid the non-specific response - do you mind elaborating please?

[G3B]

mechanical:)

I don't quite understand what the role of cilia and mucous is, and where abouts they operate and how they aid the non-specific response - do you mind elaborating please?

Mucous traps foreign material and cilia beats and moves the mucous upwards so the foreign material can be sneezed out/swallowed.

[Reus]

mechanical:)

I don't quite understand what the role of cilia and mucous is, and where abouts they operate and how they aid the non-specific response - do you mind elaborating please?

Cilia move microbes and debris (pathogens) up and out of the body. Incorporated in the cilia are goblet cells that secrete mucus which protect the lining of the bronchus and trap microorganisms, again pathogens.

Mucus acts as a physical barrier which protects the body from microorganisms that may be harmful to the body in the first line of defence.

[Reus]

Correct me if I'm wrong but the natural fauna on our skin are a part of the first line of defence as they acts as competition against potential pathogens?

[AllG_]

mechanical:)

I don't quite understand what the role of cilia and mucous is, and where abouts they operate and how they aid the non-specific response - do you mind elaborating please?

Well basically mucous and cilia are both primarily operate in the nose and respiratory tract and mucous is also found in the lungs. Mucous layer aids non-specific responses by trapping any foreign objects such as microorganisms, dust, pollen and prevents them from entering the body
Cilia help sweep trapped material away (towards the mouth) preventing it from entering the body

[RazzMeTazz]

Correct me if I'm wrong but the natural fauna on our skin are a part of the first line of defence as they acts as competition against potential pathogens?

Yes, that's correct. They compete with potential pathogens for space and nutrients, preventing colonisation of harmful pathogens on the skin. This is termed microbial competition

[AllG_]

I have two questions:

1.) On the 2013 VCAA exam for Q.11 of short answer the answer for the significance of the wider pelvic girdle in A.africanus as opposed to H.neanderthalensis is "it is harder to walk upright as it tips towards the centre of gravity."

I don't really understand the whole tipping towards the centre of gravity thing?

Bump. I don't understand this as well