VCE Biology Question Thread

[Acid]

It says mitotic division, hence is talking about the division of the nucleus during the cell cycle, mitosis. I think you have mixed it up with meiosis?

Shit, read it wrong... Thx for the clarification.

[Sine]

• evidence for biological evolution over time:
– the geological time scale; relative and absolute dating techniques

Probably the least taught area of the study design, the geological time scale, what do we need to know about it?
Also how much detail are we required to know about electron spin resonance?

[cosine]

Probably the least taught area of the study design, the geological time scale, what do we need to know about it?
Also how much detail are we required to know about electron spin resonance?

Just know this:
- Absolute dating gives an exact/absolute date for a fossil, it is probably the correct time period of existence, it is accurate. You don't need to know about the spin resonance, but do know the uses for absolute dating, like:

- Radioactive Carbon dating: Really effective for fossils <50,000 years old
- Potassium - Argon dating: Great for >50,000 years (not sure exactly how much, anyone can help?)
- Uranium dating: used for fossils that are millions of years old

For the geological time scale, there is no need to know the exact Periods and etc..

[grindr]

Could someone help with this photosynthesis ( )question?

The question was, 'Draw the expected results if the light intensity was doubled. '

The first line on the graph is the original graph,
the second horizontal line is the answer.

Why is it horizontal and not similar in shape to the original line?

[vox nihili]

Could someone help with this photosynthesis ( )question?

The question was, 'Draw the expected results if the light intensity was doubled. '

The first line on the graph is the original graph,
the second horizontal line is the answer.

Why is it horizontal and not similar in shape to the original line?

Can you attach the full question? I is confused

[StupidProdigy]

Could someone help with this photosynthesis ( )question?

The question was, 'Draw the expected results if the light intensity was doubled. '

The first line on the graph is the original graph,
the second horizontal line is the answer.

Why is it horizontal and not similar in shape to the original line?

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!

[StupidProdigy]

Are vesicles considered to be organelles? and do bacteria have vesicles (if they're not organelles...)? thanks!

[vox nihili]

Are vesicles considered to be organelles? and do bacteria have vesicles (if they're not organelles...)? thanks!

They are I guess!

[BakedDwarf]

Could someone help with this photosynthesis ( )question?

The question was, 'Draw the expected results if the light intensity was doubled. '

The first line on the graph is the original graph,
the second horizontal line is the answer.

Why is it horizontal and not similar in shape to the original line?

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

[BakedDwarf]

So i was reading the study design and came across this dot point:
"the role of enzymes as protein catalysts, their mode of action and the inhibition of the action of enzymes both naturally and by rational drug design."

What do they mean by their inhibition via rational drug design?
My guess is that we analyse the enzyme to determine its structure, particularly its active site. Then we design a drug to inhibit its active site and so to prevent its action. Is this correct?

[Biology24123]

So i was reading the study design and came across this dot point:
"the role of enzymes as protein catalysts, their mode of action and the inhibition of the action of enzymes both naturally and by rational drug design."

What do they mean by their inhibition via rational drug design?
My guess is that we analyse the enzyme to determine its structure, particularly its active site. Then we design a drug to inhibit its active site and so to prevent its action. Is this correct?

That's correct e.g enzyme on a virus

[BakedDwarf]

What do we need to know about anaerobic respiration pathways? All i know is the information below:
- Anaerobic respiration does not require oxygen
- Alcohol fermentation is an anaerobic reaction used commonly by bacteria and yeast: C6H12O6 (aq) -------> 2CH3CH2OH (aq) + 2CO2(g) + 2ATP
- Lactic acid fermentation is an anaerobic reaction that occurs in animals: C6H12O6 (aq) -----> 2CH3CH(OH)COOH (aq) + 2ATP
- The ATP produced during these reactions is from glycolysis

What's is the ATP/ADP cycle and its role?
My guess is that it's just ATP being broken down to ADP and Pi to release energy, and the opposite being ADP and Pi are converted to ATP to store chemical energy.

[katiesaliba]

Warning, images attached are of 2014 exam, so if you don't want to look at them please disregard it (cant attach pics to spoilers, sorry)

Spoiler

Question 27: It specifically says that they are two distantly related plants, so would this not mean an example of divergent evolution if these two species diverged from this related ancestor? o.O

Question 11: I have no idea why it's D, but I was able to cancel out the other options as they were contradictory to the info given. Can someone explain why it's actually D? I will provide statements of why I think the other answers are incorrect, can you also let me know if my assumptions are correct, or whether I fluked this question ?

A. When the trap is opening, potassium ions accumulate in the motor cells by diffusion: This was a bit ambiguous to me, because initially the ions all diffused out, and so when the trap actually closed, there would be a higher concentration of ions outside the cells, so as the trap is INITIALLY opening, the ions would be diffused into the motor cells facilitated by proteins. However, over some time, the concentration inside the cells would be greater than the outside as stated in the stem of question, so this would be active transport. Any suggestions ?

B. When the trap is opening, water accumulates in the motor cells by active transport: When the trap is opening, water does not undergo active transport because as the ions move back into the cells, the water would naturally diffuse into the cells to reach equilibrium? Not sure about this one..

C. When the trap is closing, potassium ions leave the motor cells because of the pressure in the surrounding cells: The ions move out because they are triggered to do so..

D. When the trap is closing, water leaves the motor cells via osmosis: Because the motor cells were turgid, when the ions diffuse outside the cell, the water would naturally want to reach equilibrium too so it would diffuse out to maintain equilibrium?

The key word here is distant. All species share a distant relative (hence evolution). It would be divergent evolution if the two species concerned shared a recent relative. Therefore, this is an example of convergent evolution.

You're almost there! It's D because when the cells lose potassium ions, they become more hypotonic to their hypertonic surroundings. Thus, water is lost from the cells via osmosis.

[sunshine98]

So came across this mcq :
The bacteria is recognised as non-self as, on it its surface , it has :
a) self antigens
b) MHC class I markers
c) MHC class II markers
d) glycopeptidase chains
why is the answer  B ? 
Thanks

[cosine]

So came across this mcq :
The bacteria is recognised as non-self as, on it its surface , it has :
a) self antigens
b) MHC class I markers
c) MHC class II markers
d) glycopeptidase chains
why is the answer  B ? 
Thanks

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.