VCE Biology Question Thread

[alondouek]

VCE BIOLOGY Q&A THREAD

To go straight to posts from 2020, click here.

What is this thread for?
If you have general questions about the VCE Biology course or how to improve in certain areas, this is the place to ask!


Who can/will answer questions?
Everyone is welcome to contribute; even if you're unsure of yourself, providing different perspectives is incredibly valuable.

Please don't be dissuaded by the fact that you haven't finished Year 12, or didn't score as highly as others, or your advice contradicts something else you've seen on this thread, or whatever; none of this disqualifies you from helping others. And if you're worried you do have some sort of misconception, put it out there and someone else can clarify and modify your understanding! 

There'll be a whole bunch of other high-scoring students with their own wealths of wisdom to share with you, including TuteSmart tutors! So you may even get multiple answers from different people offering their insights - very cool.


To ask a question or make a post, you will first need an ATAR Notes account. You probably already have one, but if you don't, it takes about four seconds to sign up - and completely free!

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Original post.

Welcome all you budding biologists! On this board there are a lot of individual-question threads throughout the year. I've made this thread both to help get your VCE biology questions answered as quickly as possible, as well as to reduce clutter on this board where possible.

Happy studying!

[alchemy]

Finally, a Biology question thread! Cheers alondouek. Would you recommend just deleting our individual question threads or transferring the content from those to over here?

[alondouek]

Hey! Definitely don't delete any of your previous posts - I'm certainly not going to transfer any existing threads here. Let's keep this thread for whatever questions may arise from now

[MM1]

What is it meant by when enzymes lower their activation energy? What exactly is activation energy?

[alondouek]

What is it meant by when enzymes lower their activation energy? What exactly is activation energy?

Activation energy (Ea) is the minimum energy input needed for a chemical reaction to occur. All reactions need some energy input to facilitate their occurrence, but the Ea is often too high for biological systems, which are vulnerable to heat and other forms on high-energy situations.

Enzymes are biological catalysts. Catalysts lower the Ea of a chemical reaction system, which means the energy "currency" of the reaction is within more a more manageable range that the biological system (e.g. an organism) can manage without sustaining any damage. Biocatalysis is also important because organisms only have a certain amount of energy that they can devote to biological reaction systems, which means that by lowering the required energy input for vital biochemical reactions, the organism's energy input (such as food) can be reduced.

[grannysmith]

What is it meant by when enzymes lower their activation energy? What exactly is activation energy?

I feel as if this wording is slightly misleading.

As alondouek has mentioned, activation energy is the input of energy required for a chemical reaction to take place. However, in the presence of an enzyme, this is lowered as enzymes are biological catalysts.

[MM1]

Activation energy (Ea) is the minimum energy input needed for a chemical reaction to occur. All reactions need some energy input to facilitate their occurrence, but the Ea is often too high for biological systems, which are vulnerable to heat and other forms on high-energy situations.

Enzymes are biological catalysts. Catalysts lower the Ea of a chemical reaction system, which means the energy "currency" of the reaction is within more a more manageable range that the biological system (e.g. an organism) can manage without sustaining any damage. Biocatalysis is also important because organisms only have a certain amount of energy that they can devote to biological reaction systems, which means that by lowering the required energy input for vital biochemical reactions, the organism's energy input (such as food) can be reduced.

Thank you!

[MM1]

I feel as if this wording is slightly misleading.

As alondouek has mentioned, activation energy is the input of energy required for a chemical reaction to take place. However, in the presence of an enzyme, this is lowered as enzymes are biological catalysts.

What is it meant by when enzymes lower their activation energy? What exactly is activation energy?   ?

Thanks!

[alondouek]

What is it meant by when enzymes lower their activation energy? What exactly is activation energy?   ?

Thanks!

I think Oddly was referring to something else in the wording haha; enzymes don't lower their activation energy, they lower the activation energy of the reaction.

[MM1]

I think Oddly was referring to something else in the wording haha; enzymes don't lower their activation energy, they lower the activation energy of the reaction.

Oh, oops silly mistakes. Thanks for the clarification though.

[DJA]

What is the difference between carrier mediated protein channels and channel mediated protein channels in the phospholipid bilayer of the plasma membrane?? (i do know that they both do not require energy...but thats it)

And I am not referring to the active transport carrier protein where energy is required to carry substances through the plasma membrane.

Edit: The diagram I am pondering over and not understanding is on pg 44 of the Nature of Biology TB if anyone has that text.
(3 types of passive transport: Simple diffusion, Channel mediated, Carrier mediated: the last two I do not get the difference)

[Yacoubb]

What is the difference between carrier mediated protein channels and channel mediated protein channels in the phospholipid bilayer of the plasma membrane?? (i do know that they both do not require energy...but thats it)

And I am not referring to the active transport carrier protein where energy is required to carry substances through the plasma membrane.

Edit: The diagram I am pondering over and not understanding is on pg 44 of the Nature of Biology TB if anyone has that text.
(3 types of passive transport: Simple diffusion, Channel mediated, Carrier mediated: the last two I do not get the difference)

Carrier mediated transport involves a carrier protein. The carrier protein binds to the substance and undergoes a conformational change as it is bound to the substance. This molecule then possesses a specific shape that enables it to pass through a specific porous protein channel. Some substances do not require carrier proteins; channel mediated transport involves the substance travelling across the cell membrane via specific porous protein channels, into or out of the cell. And then as you already know, these are means of facilitated diffusion, and so are passive and require not ATP energy input in order to take place.

Hope this helped!

[DJA]

Carrier mediated transport involves a carrier protein. The carrier protein binds to the substance and undergoes a conformational change as it is bound to the substance. This molecule then possesses a specific shape that enables it to pass through a specific porous protein channel. Some substances do not require carrier proteins; channel mediated transport involves the substance travelling across the cell membrane via specific porous protein channels, into or out of the cell. And then as you already know, these are means of facilitated diffusion, and so are passive and require not ATP energy input in order to take place.

Hope this helped!

Thanks-a huge help!

[DJA]

What are the major biological processes that need to be known for VCE and more importantly how much detail is needed?
My current list so far is:
Protein synthesis
ATP/ADP cycle
Photosynthesis
Let me know what I am missing in the way of processes.

Edited twice

[Yacoubb]

What are the major biological processes that need to be known for VCE and more importantly how much detail is needed?

My current list so far is:
Protein synthesis
ATP/ADP cycle
Photosynthesis

Let me know what I am missing in the way of processes.

* Means of transport across the plasma membrane; osmosis, diffusion, facilitated diffusion, active transport and vesicular transport (including endocytosis and exocytosis).
* Protein Synthesis & Secretory Pathway - by time you finish the course, you must know transcription & translation in depth, and the pathway from the nucleus --> ribosome --> rough endoplasmic reticulum --> golgi complex --> secretory vesicle. At each stage, you must know what occurs.
* Enzyme activity: what is an enzyme, what is the role/importance of enzymes, factors affecting enzyme activity, including pH, temperature, enzyme/substrate/product concentration, inhibition and cofactor/coenzyme concentration.
* Photosynthesis: inputs and outputs, as well as location within the chloroplast of the light dependent & light independent stages of photosynthesis, as well as how photosynthetic rate is dependent on CO2 and light.
* Cellular respiration: the difference between aerobic and anaerobic respiration, including ATP energy yield per glucose molecules, inputs and outputs and location of each stage within the cell/within the mitochondrion (for Krebs Cycle and Electron Transport Chain in aerobic respiration).

That's Area of Study 1