VCE Biology Question Thread

[cosine]

Okay so think about it this way. When the trap is open, the motor cells in the mid-rib are highly concentrated in K+ ions. Because of this, the water will be highly concentrated in the motor cells in the mid-rib. Water always wants to be in the regions where solute concentration is highest (attempting to balance the concentrations). When the trap is closing though, the surrounding cells need to become turgid (they literally become heavier which induces the trap to close). So the only way that water can move out of the motor cells in the mid-rib and into the surrounding cells is by the facilitated diffusion of K+ions into those surrounding cells. Given that water moves from regions of low to high SOLUTE concentration to establish some sort of equilibrium in concentrations, water will move OUT of the motor cells, because now the surrounding cells are concentrated with K+, more so than the motor cells of the mid-rib. If you still have confusion let me know

But you automatically assumed that there is a high concentration of water inside the mid - rib cells? Where in the question does it say this? Still don't get it

[Yacoubb]

But you automatically assumed that there is a high concentration of water inside the mid - rib cells? Where in the question does it say this? Still don't get it

Well the question tells us that in the resting state when the trap is open, K+ ions are highly concentrated in the mid-rib cells. We know that wherever the solute concentration is VERY high (as is alluded to regarding K+ ions), we know there will be a net movement of water towards (by osmosis). Same thing goes when the K+ ions move out of the motor cells by facilitated diffusion ~ there will be a net movement of water in the same direction OUT as the K+ ions.

[tashhhaaa]

Hey guys,

I've just started my Unit 3 notes (slack I know lol) and I was wondering, do we need to know about carbohydrates to this level of detail? The study design says 'examples of polysaccharides and their glucose monomer' but I'm not sure what is exactly needed :/

[heids]

Hey guys,

I've just started my Unit 3 notes (slack I know lol) and I was wondering, do we need to know about carbohydrates to this level of detail? The study design says 'examples of polysaccharides and their glucose monomer' but I'm not sure what is exactly needed :/

No, you don't.

Learn:
> what glucose looks like, its basic chemical structure (evil VCAA caught us out with amino acid structure in 2014, so they're liable to ask you to draw glucose since it's specifically mentioned in the SD).  You'll obviously know a bit more about it from respiration, too.
> know that monosaccharides = single molecule, di = 2 molecules, poly = lots
> know the basic function, and maybe basic structure, of:
--------> cellulose: tough structural component of plant cell walls
--------> starch: stores energy in plants
--------> glycogen: stores energy in animals
--------> chitin: structural component of fungi cell walls, exoskeleton in hard critters

[tashhhaaa]

No, you don't.

Learn:
> what glucose looks like, its basic chemical structure (evil VCAA caught us out with amino acid structure in 2014, so they're liable to ask you to draw glucose since it's specifically mentioned in the SD).  You'll obviously know a bit more about it from respiration, too.
> know that monosaccharides = single molecule, di = 2 molecules, poly = lots
> know the basic function, and maybe basic structure, of:
--------> cellulose: tough structural component of plant cell walls
--------> starch: stores energy in plants
--------> glycogen: stores energy in animals
--------> chitin: structural component of fungi cell walls, exoskeleton in hard critters

thanks so much!!!

[BakedDwarf]

Yeah, I believe it is required to know the basic structure of starch, glycogen and cellulose because I've seen a few questions on commercial exam papers* regarding this. Understanding that glycogen is highly branched, starch is moderately branched and cellulose is unbranched and linking this to their function should be sufficient.

* Not VCAA ones, so I'm not entirely sure if you will be tested on this on the exam, but it wouldn't hurt to know.

[BakedDwarf]

Is pure breeding when a homozygous organism is crossed with a homozygous organism?

[tashhhaaa]

Yeah, I believe it is required to know the basic structure of starch, glycogen and cellulose because I've seen a few questions on commercial exam papers* regarding this. Understanding that glycogen is highly branched, starch is moderately branched and cellulose is unbranched and linking this to their function should be sufficient.

* Not VCAA ones, so I'm not entirely sure if you will be tested on this on the exam, but it wouldn't hurt to know.

thanks!

[Sine]

Hey

Great to see the thread being very active!

I have a few questions on genetics:
What exactly is a test cross? Is it between a organism with recessive phenotypes and any other organism or does this other organism need to have a specific phenotype?

How do we know the probability of recombinant gametes being formed due to crossing over? (to create punnet squares)

[vox nihili]

Hey

Great to see the thread being very active!

I have a few questions on genetics:
What exactly is a test cross? Is it between a organism with recessive phenotypes and any other organism or does this other organism need to have a specific phenotype?

How do we know the probability of recombinant gametes being formed due to crossing over? (to create punnet squares)

A test cross is a cross to a homozygous recessive organism. Whatever the other organism is doesn't really matter. The test cross will always reveal the genotype of the other organism though.

You don't. You'll never need to answer questions that require that knowledge. Good thinking though, it is very doable but beyond the course.

[Rumena]

Heyy!!
I just wanted to ask if anyone has done their first sac on unit 4? If you have can you please tell me what I need to focus the more on? It would really help me, thanks!!😋

[cosine]

Few more questions from a Neap Exam:

Question 10:
i. Concentration of CO2 in the leaf
ii. Concentration of the O2 in the leaf
iii. Temperature

Which factors affect the output of the light-independent reactions of photosynthesis in plants?

Answer: All of the above.

My confusion: I understand how concentration of CO2 affects the output, because it is a vital component of the independent cycle, and temperature I understand, but how does the concentration of the oxygen affect the output? Isn't oxygen the byproduct of the light dependent stage, so what has this to do with the independent stage?


Question 11:
An electron transport chain is an essential part of the following cellular processes of?

Answer: Aerobic respiration and photosynthesis.

My confusion: I know the electron transport chain occurs in cellular respiration, and I think i also knew about it in photosynthesis during the light dependent stage, but are we required to know that ETC also occurs during photosynthesis?

Question 2:
RNAP catalyses many steps in the process where DNA is converted into RNA. This is quite unusual in that most enzymes catalyse only one reaction. Using your understanding of enzyme structure and function, give one reason which would explain how RNAP can catalyse many steps.

Answer: Enzymes have many active sites for different substrates OR the RNAP can be a quaternary structured enzyme

My confusion: Would this ever be a VCAA question? I mean i never knew enzymes had more than one active site, do they even or is Neap just weird? My original answer was that there many be several substrates that are complementary to the enzyme's active site.

General questions:

- Do we need to know the chemical formula for cellular respirations?
- Can someone please list the required info to include in an experiment designing question?

Thanks

Anyone please ?

[sunshine98]

Do we have to know about how stomata opens and closes (with the K moving in and then water moving in...)?

Thank you 

[HighTide]

Anyone please ?

Hi Cosine,
10. So oxygen concentration does affect the rate of photosynthesis. There's a process called photorespiration occurring in plants which prevents photosynthesis occurring to its full potential. In photosynthesis, RuBP and carbon dioxide are needed. However, in photorespiration, oxygen competes with carbon dioxide for RuBP and therefore the reaction rate is influenced by the presence of oxygen.
11. Yes, you should know that ETC occurs in photosynthesis too. About those questions regarding whether you're expected to know something, there's no harm in knowing it occurs but make sure you don't make assumptions and don't go off on a tangent!
12. Lol. That question. Anyway, it's similar to an application question so VCAA can use it to test your understanding of the concepts. They will give background info if it's something way off the study design. It's good doing exam papers, as it gives you an idea of the unusual questions and answers which may benefit you when the exam comes up!

Um, by that first general question, I assume you're referring to the equation? Yes you must know the balanced equation for photosynthesis and cellular respiration.
For the experimental design, I think someone posted this a while back.
You'll need to state:
Aim, hypothesis, the independent and dependent variables, control groups, method.
They can also ask you to explain limitations, improving experiment and minimizing error and also results.

Do we have to know about how stomata opens and closes (with the K moving in and then water moving in...)?

I'm fairly certain (not 100%) that's also in the scope of VCE bio. You should know about guard cells. Perhaps, just to confirm, hopefully someone else can answer this. Yet again, there's no harm in knowing 

 

[cosine]

Hi Cosine,
10. So oxygen concentration does affect the rate of photosynthesis. There's a process called photorespiration occurring in plants which prevents photosynthesis occurring to its full potential. In photosynthesis, RuBP and carbon dioxide are needed. However, in photorespiration, oxygen competes with carbon dioxide for RuBP and therefore the reaction rate is influenced by the presence of oxygen.
11. Yes, you should know that ETC occurs in photosynthesis too. About those questions regarding whether you're expected to know something, there's no harm in knowing it occurs but make sure you don't make assumptions and don't go off on a tangent!
12. Lol. That question. Anyway, it's similar to an application question so VCAA can use it to test your understanding of the concepts. They will give background info if it's something way off the study design. It's good doing exam papers, as it gives you an idea of the unusual questions and answers which may benefit you when the exam comes up!

Um, by that first general question, I assume you're referring to the equation? Yes you must know the balanced equation for photosynthesis and cellular respiration.
For the experimental design, I think someone posted this a while back.
You'll need to state:
Aim, hypothesis, the independent and dependent variables, control groups, method.
They can also ask you to explain limitations, improving experiment and minimizing error and also results.
I'm fairly certain (not 100%) that's also in the scope of VCE bio. You should know about guard cells. Perhaps, just to confirm, hopefully someone else can answer this. Yet again, there's no harm in knowing 

10. do we have to know about this in VCE?

11. I know what happens during the ETC in cellular respiration, but do we need to know about cytochromes also? And what happens in ETC in photosynthesis that we need to know?

12. can you answer my question for it? so does that mean quaternary enzymes have multiple active sites, and can bind to  more than one substrate? (is this for VCE level though?, because we define enzymes as only complementary to it's specific substrate, not substrates

Thank you HighTide xD