VCE Biology Question Thread

[sunshine98]

The answer is not B, MHC Class I markers are actually only found on mammals, and bacteria are not mammals. The answer is D, I asked this question a long time ago and Mr. T-Rav said this is a stupid question, and not to worry about it ~ clearly outside the study design.

I  choose D too, makes much more sense. Thanks 

[grindr]

Can you attach the full question? I is confused

Sure, I've attached it here.

[grindr]

I'm pretty confident this is why, but someone correct me if I'm wrong!! It's because there are different types of chlorophyll responsible for absorbing different wave lengths of light. As well as the activation of different types of chlorophyll, some chlorophyll types also become less active and even dysfunctional at higher light intensities, which would explain the changes in gradient of the second graph. So new intensities gives different wave lengths for different chlorophyll types which may either have a negative, neutral or positive effect. Or maybe I'm just making things up hahaha, I think that's it though
edit: would obviously of needed some background information in the question for this assumption!

Okay, but why do we assume that the graph is then horizontal, and not some other shape?

[grindr]

Isn't it simply because:
more light ---> higher rate of photosynthesis (considering light was the limiting factor) ---> more CO2 used up from the environment ---> hence, lower amount of CO2 in environment

Can you explain the horizontal line? Or is the shape of the graph not crucial and any answer would be accepted given that the new line is lower than originally?

[grindr]

I need help with this exergonic/endergonic question please.

Name the reaction suggested by use of ATP.
The answer is endergonic.

I know that use of ATP means that the reaction is endergonic, however in the equation, ATP is being converted  to ADP, and isn't that an exergonic process?

[cosine]

I need help with this exergonic/endergonic question please.

Name the reaction suggested by use of ATP.
The answer is endergonic.

I know that use of ATP means that the reaction is endergonic, however in the equation, ATP is being converted  to ADP, and isn't that an exergonic process?

Endergonic reactions are those that build larger and more complex molecules from simpler ones, also requiring a net input of energy. So because this reaction started off with two reactants, and only 1 product, you can clearly see that the product is a much larger and complex molecule than what we started off with. Don't worry too much about the ADP + Pi because that's just a by product, it supplies the energy and it's gone.

[cosine]

How would one link biological, and cultural evolution to humans having more control over their environment(technological evolution) resulting in technologies such as cloning?

Biological evolution and cultural evolution helped humans advance in the technology world, which is probably the reason why humans are the most dominating animals in this world. Cultural evolution helped us evolve by becoming more smarter and intelligent, a really beneficial outcome of having larger brains (biological evolution). Having larger brains allowed the Homo ancestors to actually develop much more advanced tools, weapons and other necessary equipment to have an advantage over other animals. Those tool makings and weapons have evolved throughout time as humans became more and more smarter till this point, where amazing technologies such as cloning are possible because of our ability of a). such ameliorated conceptual language and communication skills (cultural) which helps us pass down our knowledge to future generations and b). biological evolution leading to larger brains (sure there are more than just the brain) as a result of improved diets from the ancestors, and obviously larger brains means Homo Sapiens are capable of more intelligence and hence are able to invent and create new technological breakthroughs.

[angelrox00]

Hi everyone, Could you guys please have a look at the question below;

A human bone was found in a cave and its carbon-14 content was analysed in order to date it.
It was found that 1/8 of its original carbon-14 content remained. The half-life of carbon 14 is
5730 years. How old is the bone?
A. 11460 years.
B. 17190 years.
C. 22920 years.
D. 28650 years.

Thanks very much!
May God Bless you!
~Angel Raju,

[sunshine98]

Hi everyone, Could you guys please have a look at the question below;

A human bone was found in a cave and its carbon-14 content was analysed in order to date it.
It was found that 1/8 of its original carbon-14 content remained. The half-life of carbon 14 is
5730 years. How old is the bone?
A. 11460 years.
B. 17190 years.
C. 22920 years.
D. 28650 years.

Thanks very much!
May God Bless you!
~Angel Raju,

is the answer b ?
That 1/8 of the carbon remains means the carbon content has halved three times (1/2^3 = 1/8). It takes 5730 years to half so 5730*3 = 17190 so b.

[vox nihili]

Sure, I've attached it here.

Hmm still not sure why it's horizontal. It's obviously under because the rate of photosynthesis is greater than the rate of respiration, but why it's horizontal I have no idea. It could just be that they've drawn it that way to illustrate that students merely needed to put the line under the x-axis.

[THEBEAST]

Can someone please explain to me about the Rh +ve and Rh -ve relationship between a mother and her baby and what is the function of a doctor injecting Rh antibodies into the mother?

[cosine]

Hi everyone, Could you guys please have a look at the question below;

A human bone was found in a cave and its carbon-14 content was analysed in order to date it.
It was found that 1/8 of its original carbon-14 content remained. The half-life of carbon 14 is
5730 years. How old is the bone?
A. 11460 years.
B. 17190 years.
C. 22920 years.
D. 28650 years.

Thanks very much!
May God Bless you!
~Angel Raju,

Sunshine98 is right, it's B because:

Half life of Carbon14 is 5730 years, and so every 5730, the original sample remaining reduces it's mass by a half, hence half-life. So half the original sample to get \frac{1}{2} of the initial amount of carbon, so to reach this point of deterioration, 5730 years have passed. Now half that again, and you will get \frac{1}{4} and add another 5730, so total: 5730+5730 = 11460. Now half that again to get \frac{1}{8} and hence add another 5730 to the years: 11460 + 5730 = 17190 years.

[sunshine98]

Can someone please explain to me about the Rh +ve and Rh -ve relationship between a mother and her baby and what is the function of a doctor injecting Rh antibodies into the mother?

So this circumstance only occurs when :
- Rh -ve mother
- Rh +ve child
Remember Rh antigens are proteins on the surface of RBC.
So once the mother gives birth the child's blood may pass through the placenta and into her body. Because she is Rh negative her immune cells will detect it as foreign, leading to the production of antibodies and what is most important here - memory B cells.
The real problem , however, occurs at the second child (given that he/she too is Rh +ve)
During pregnancy some cells will pass through to the mother. Antibodies are produced rapidly and greatly. They will attack the childs RBC leading to damage and causing haemolytic disease ,where child is yellowy because RBC lyse and haemoglobin is released.
Now at each subsequent pregnancy response will be stronger and greater, due to the presence of memory B cells. 
How can we prevent this? At the first child birth the  mother is injected with antibodies for the Rh factor (this is passive artificial immunity) so that she doesn't produce her own , and no memory cells are produced. This is repeated at each child birth .

 

[grindr]

Hmm still not sure why it's horizontal. It's obviously under because the rate of photosynthesis is greater than the rate of respiration, but why it's horizontal I have no idea. It could just be that they've drawn it that way to illustrate that students merely needed to put the line under the x-axis.

Okay, thanks

Endergonic reactions are those that build larger and more complex molecules from simpler ones, also requiring a net input of energy. So because this reaction started off with two reactants, and only 1 product, you can clearly see that the product is a much larger and complex molecule than what we started off with. Don't worry too much about the ADP + Pi because that's just a by product, it supplies the energy and it's gone.

Right, thanks

[cosine]

Can someone explain to me why the answer is not B, C or D?

Here is my thoughts:
B. Mast cells are leucocytes, and we know that blood cells are produced in the bone marrow - mast cells are not lymphocytes, so they're not involved in the lymphatic system?
C. Vessels have thick, muscular walls, unsure about this one, I just know that lymph vessels only flow fluids one way
D. Lymph is pumped by the heart, I am pretty sure lymph is pumped through muscular contractions?