VCE Biology Question Thread

[cosine]

Follow up question to your post: Do I need to know what ATP synthase is?

Not specifically, but there is required knowledge of the 'ase' representing enzymes. So ATP synthase is obviously the enzyme that catalyses the synthesis of ATP.

[blacksanta62]

Ok. So I should know that the enzyme ATP synthase helps with the synthesis of ATP. Thanks Cosine

Edit: Is the role of Rubisco in photosynthesis required knowledge? I still don't fully understand role. I think It helps bind CO2(g) but what else it do? Thanks

[cosine]

Ok. So I should know that the enzyme ATP synthase helps with the synthesis of ATP. Thanks Cosine

Edit: Is the role of Rubisco in photosynthesis required knowledge? I still don't fully understand role. I think It helps bind CO2(g) but what else it do? Thanks

Yes you are, only because the 'ase' is at the end of the molecule. So you are also required to know that protease is an enzyme that catalyses the anabolism/catabolism (dont need to know which, key info is the ase hence enzyme) or proteins.

No need to learn about Rubisco at all. Just know that in the light-independent reactions, CO2 is converted into Glucose (simple sugars) and that NADPH and ATP from the light dependent reactions are consumed in the light independent, and that it occurs in the stroma of the chloroplasts.

[geminii]

Where does cellular respiration occur in bacteria?

[cosine]

Where does cellular respiration occur in bacteria?

It occurs in the cytoplasm. Read what I said on the previous space that will help you understand how they respire aerobically in their cytoplasm without mitochondria, as they lack membrane-bound organelles.

[chiara.cats]

Im currently undertaking VCE 1 & 2 biology and was wondering if any of you guys would be able to help me with the role of NADPH in photosynthesis? and then a separate question to that is what is the purpose of ATP, ADP and Pi in photosynthesis? thank you so much in advance.

[ANother1]

If you were to use a 10 percent salt (saline) solution to relieve nasal congestion (a stuffy nose), what do you think would happen to the cells lining the nasal cavity, and why?

[cosine]

Im currently undertaking VCE 1 & 2 biology and was wondering if any of you guys would be able to help me with the role of NADPH in photosynthesis? and then a separate question to that is what is the purpose of ATP, ADP and Pi in photosynthesis? thank you so much in advance.

NADPH 'carries' a hydrogen atom as well as electrons to the light-independent reactions that occur in the stroma, and these are consumed there to produce the final product of glucose. That is all you need to know about NADPH. ATP is synthesised during the light-dependent stage. Basically, ADP + Pi come along, and they are bonded together to form ATP. This ATP molecule is the universal energy source for many organisms. So this is used to drive, provide energy for the light-independent reactions.

[vox nihili]

If you were to use a 10 percent salt (saline) solution to relieve nasal congestion (a stuffy nose), what do you think would happen to the cells lining the nasal cavity, and why?

You tell us first. Reasonably straight forward!

Hint: osmosis

[ANother1]

You tell us first. Reasonably straight forward!

Hint: osmosis

asking for a friend, yikes

[blacksanta62]

Hello, I'm doing a prac/SAC fairly soon about photosynthesis. Teacher hasn't given out any questions or anything but she suggested I go and think about certain things we read in the handout so I have some questions.

The prac is about Elodea in the test tube and the effect light intensity will have on photosynthesis. One of the key steps was to ensure total darkness for 2 minutes before exposing it to light for 30 seconds (or something around that) and counting the O2 bubbles then moving the lamp further away. Was this to simulate the night period plants experience in which photosynthesis cannot take place? And also 'restart' photosynthesis, so we could get a more accurate measure from the time the plant was exposed to light?

Would the IV be the amount of light given to the plant while the DV is the amount of O2 bubbles produced?

We're using tap water in this prac. Tap water contains ions and the thylakoid membranes are made of a phospholipid bilayer, Is there anything important about this? Or is this to simulate the natural pond surrounding the elodea

Thank you

Edit: Bump. Some more questions:
1) The prac setup included a thermometer in the solution, why is this necessary when measuring light intensity and it's affect on photosynthesis? Is the lamp strong enough to raise the temperature of the water?

2) When the lamp was close to the beaker O2(g) bubbles produced was high, does this mean that either CO2(g) conc or temperature are the limiting factors? Furthermore, when we moved the lamp further away the the O2(g) produced was lower, is light intensity now the limiting factor?

3) Can too much light intensity damage the enzymes at all?

My sac is tomorrow, thanks

[anniebrejcha]

hi guys!!!
would anyone be able to help me answer:
how might a drug improve lactose digestion in bacteria by acting on transcription process?
thanks in advance!

[anniebrejcha]

hi guys!!!
would anyone be able to help me answer:
how might a drug improve lactose digestion in bacteria by acting on transcription process?
thanks in advance!

also!! could someone please explain the krebs cycle to me ; i really just cant get it.

[cosine]

asking for a friend, yikes

Well if the cells are placed in a salt solution, we assume that they are placed in a hypertonic solution. So, this means that the water inside the cells is at a higher concentration as compared to the extracellular fluids, hence the water diffuses out into the lining, which would relieve the congestion. Also, take note that the solution was only 10% salt solution, hence the osmotic gradient was not large enough to crenate the cells.

hi guys!!!
would anyone be able to help me answer:
how might a drug improve lactose digestion in bacteria by acting on transcription process?
thanks in advance!

So we know that genes are switched on and off, relative to when the cell/tissue/organ/organism needs the product (protein) most. So, to improve lactose digestion, we will assume that the bacterial cells need an excess of lactase, the enzyme that catabolises lactose into its constituent monosaccharides. So a drug can promote the transcription of the lactase gene, by acting as an 'activator' protein, in VCE, no need to know more than that, simply that some proteins/drugs/molecules act as gene activators, and if this drug activates the gene transcription regardless of whether the cell does it manually or not, then the lactase gene will be transcribed and eventually translated into lactase.

also!! could someone please explain the krebs cycle to me ; i really just cant get it.

Krebs cycle is the first step of cellular aerobic respiration. So the products of glycolysis, which is 2 pyruvate molecules, enter the mitochondrial matrix and here they are ready to undergo the Krebs cycle. So one pyruvate molecule reacts with CoA (coenzyme A, no need to know what this is exactly) to produce a molecule of CO2, NADH and Acetyl CoA. The Acetyl CoA undergoes further biochemical reactions to further produce 3NADH molecules, FADH2, ATP and another 2 CO2 molecules. So, in total, as there are 2 molecules of pyruvate per glucose molecule, the outputs of the Krebs cycle from 1 glucose are: 6CO2, 8NADH, 2FADH2, 2ATP.

Drawing an actual cycle or diagram really helped me memorise the steps and products, because in VCE knowledge, this step is best memorised as there are in reality thousands of reactions that are involved, so draw a diagram and put it up on your wall so that everytime you look up, you see it.

[anniebrejcha]

Well if the cells are placed in a salt solution, we assume that they are placed in a hypertonic solution. So, this means that the water inside the cells is at a higher concentration as compared to the extracellular fluids, hence the water diffuses out into the lining, which would relieve the congestion. Also, take note that the solution was only 10% salt solution, hence the osmotic gradient was not large enough to crenate the cells.

So we know that genes are switched on and off, relative to when the cell/tissue/organ/organism needs the product (protein) most. So, to improve lactose digestion, we will assume that the bacterial cells need an excess of lactase, the enzyme that catabolises lactose into its constituent monosaccharides. So a drug can promote the transcription of the lactase gene, by acting as an 'activator' protein, in VCE, no need to know more than that, simply that some proteins/drugs/molecules act as gene activators, and if this drug activates the gene transcription regardless of whether the cell does it manually or not, then the lactase gene will be transcribed and eventually translated into lactase.

Krebs cycle is the first step of cellular aerobic respiration. So the products of glycolysis, which is 2 pyruvate molecules, enter the mitochondrial matrix and here they are ready to undergo the Krebs cycle. So one pyruvate molecule reacts with CoA (coenzyme A, no need to know what this is exactly) to produce a molecule of CO2, NADH and Acetyl CoA. The Acetyl CoA undergoes further biochemical reactions to further produce 3NADH molecules, FADH2, ATP and another 2 CO2 molecules. So, in total, as there are 2 molecules of pyruvate per glucose molecule, the outputs of the Krebs cycle from 1 glucose are: 6CO2, 8NADH, 2FADH2, 2ATP.

Drawing an actual cycle or diagram really helped me memorise the steps and products, because in VCE knowledge, this step is best memorised as there are in reality thousands of reactions that are involved, so draw a diagram and put it up on your wall so that everytime you look up, you see it.

thanks a heap! this really helped me out.