Hey guys, I have a few questions about Unit 3 Biology that I either did not understand or I still have knowledge gaps about, hopefully someone can help me 
Cellular respiration:
1). How does glucose enter a cell for the uptake of glucose so that cellular respiration can occur? Does glucose just simply go along the concentration gradient from the extracellular fluids down into the cell through facilitated diffusion?
2). Once glucose has entered a cell, how exactly is it broken down into the 2, 2-Carbon molecules (pyruvate)? Does this reaction happen under the facilitation of enzymes and ATP?
3). Do we need to know that 2ATP molecules are used up in glycolysis, but 4ATP molecules are produced, meaning a net production of 2 ATP molecules are made during glycolysis?
4). Why is there a carrier molecule involved in glycolysis? Does this carrier molecule just pick up hydrogen ions and electrons to transport into the krebs cycle/electron transport chain?
5). Do we need to know the inputs/outputs of the krebs cycle with specific numbers, like 3CO2 molecules are produced for each pyruvate, 4NADH and 1FADH2?
6). Do we need to know about coenzyme A? (The molecule which reacts with pyruvate to produce CO2 and NADH)
7). How many ATP molecules occur during the krebs cycle? Is it just 1 per pyruvate?
. How much do we need to know about the electron transport chain? Is it okay to just know that most of the ATP production occurs during this process, and that this occurs in the inner membrane of the mitochondria?
9). 2 ATP are made during glycolysis, 2 ATP during krebs cycle, and 34 in the ETC. Total of 38 ATP right?
10). Why does glucose break down to form ATP? Is it just because it is easier for the body to use smaller molecules as a means of energy, rather than the massive molecule glucose?
11). How much do we need to know about anaerobic respiration? Is it just that in animals, without oxygen the pyruvate is converted into lactic acid, and in plants into ethanol (alcohol)?
12). Does krebs cycle use oxygen? My guess is yes, because pyruvate is a 3-carbon molecule, and is converted into carbon dioxide, so I would think that oxygen is required for the process?
Signalling:
1). I know the importance of the reflex arc, but how does it actually work? Is the stimulus detected, and then the sensory neurones bypass the brain, and go straight to the spinal cord (does this mean the spinal cord is the control centre in this case?) and then from there motor neurones order the effector to act?
2). Do we need to know the feedback loops for the exam?
3). Is the main difference between negative and positive feedback that negative is trying to eliminate the stimulus, much like it's a bad thing, whereas positive feedback just enhances the stimulus?
4). Do neurones communicate with normal body cells? If so, how do they do this?
5). What detect the stimulus? Like If you put your hand on a hot surface, is it the mechanoreceptors that detect the stimulus, or is it the sensory neurones?
6). What's the difference between PNS and CNS? Is the central nervous system the neurones involved in the brain and spinal cord, whereas the peripheral nervous system is the outer network of neurones in the rest of the body?
7). Are interconnecting neurones found in the brain/spinal cord, or only brain? What do these neurones do?
Thanks so much if anyone can help 
Thanks for actually trying to answer some of your own questions, an important thing to do in my view if you want to learn
Respiration:
1. Glucose transport is tricky. Glucose can enters cells via carrier proteins, but this process can be either active or passive. So glucose can enter cells via facilitated diffusion or active transport.
2. Correct. A series of ten reactions, collectively referred to as glycolysis, give rise to pyruvate from glucose. This process involves all sorts of enzymes/coenzymes etc. Naturally, all you need to know are the inputs and outputs.
3. It can't hurt knowing that, although I'm not convinced VCE examiners would be that pedantic.
4. Hmmm I'm not sure that carrier molecule is the correct word. I assume you're referred to NAD+/NADH. The reduction of NAD+ to NADH during glycolysis and Krebs is extremely important. Electrons and protons from NADH form the basis of the electron transport chain. You don't really need to know the details of this, however, other than that it happens.
5. Yes, you need to know the inputs and outputs of each stage.
6. Yes, CoA is an important part of the process. You don't need to know any more than that it reacts with pyruvate to form acetyl CoA, which is the molecule that enters the Krebs cycle.
7. Correct. Although, you are better to remember numbers per glucose. So it is two ATP per glucose.
8. I think that that understanding would probably be sufficient. The details of the electron transport chain are well beyond what could reasonably be expected of year 12 biology students.
9. 32-34 in the ETC, leading to a total of 36-38. In truth, this number actually varies more widely; however, the VCE course represents it as such.
10. Kind of. Bonds contain energy. Therefore, if you break bigger molecules into smaller molecules, you release energy. This release of energy can be used to drive the production of other, bigger molecules. In the context of cellular respiration, the breaking of bonds is used to produce ATP from ADP and Pi, and also produce NADH from NAD+ and H.
11. You should know the inputs and outputs of fermentation and lactic acid production.
12. I'm glad that you had a guess on this one; it is wrong however. The only process that uses oxygen is the ETC. In the context of cellular respiration, oxygen is the so-called final acceptor, meaning that it takes the electrons from the ETC and uses them to react with hydrogen ions to form water.
If you look at the chemical structure of pyruvate, you will notice that it contains a number of oxygen atoms inherently. It is these atoms that go on to form carbon dioxide.
Signalling:
1. That's correct. Most signals from the body come back to the brain via the spinal cord, but in the case of a reflex arc, the sensory neurone interfaces directly with a motor neurone (or via an interneurone), meaning that a response is generated without input from the brain.
2. You don't need to know specific pathways—though having an example handy is a must. You should, however, be able to look at a pathway and explain how it works. YOu'll be given enough prompt material to explain how it works without having had to have seen the pathway before.
3. This is the difference. Negative feedback opposes the stimulus; whereas, positive feedback reinforces the stimulus.
4. I don't know what you mean by normal body cells.
5. Mechanoreceptors are a type of sensory neurone. There are many different forms of sensory neurone: taste receptors, mechanoreceptors, nociceptors (pain), thermoreceptors and so on. Each of these sensory neurones responds to a different type of energy. In the context of a hot surface, the heat is likely to be registered by thermoreceptors and nociceptors. Heat is not a mechanical energy, so mechanoreceptors will be unresponsive to it.
6. Correct.
7. Interneurones are found in the brain and the spinal cord. They pass signals between the sensory system and the motor system and do a lot of the "planning" in the brain.
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