Well done on asking some really good questions but I have now created a second faq page for biol 1.
Please write your questions on this page from now on. Link is below.


biol 1 faq (nsfaq) part2
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Q. Are all single-celled living organisms prokaryotes?

A. This is not actually the case. In fact, all single-celled living organisms (protista) are eukaryotes. They all have a distinct nucleus and membrane bound organelles. (that is what it says in my book) Josh
Well done Josh, bacteria and protista are single-celled organisms but only bacteria are prokaryotes. Hence not all single-celled organisms are prokaryotes.VM




Q. Can anyone tell me why the phospholipids are arranged the way they are in a plasma membrane? Still not clear on this.

A. The phospholipids are arranged the way they are because the heads of the phospho lipids are hydrophilic, meaning they are attracted to/like the water which sorrounds the plasma membrane. the tails of the phospholipids are hydrophobic meaning they dont like the water, so they are turned to face inside the cell membrane. As you can see in any diargram, there is not much room for things to enter the cell membrane because the phospholipids are so close together, so there is a larger tunnel for the bigger matter to get inside. these 'tunnels' are call protein channels.
i hope that answers the question, anyone is able to correct me or add something i have left out. josh
Great answer. Spot on.VM



Q. I know that chloroplasts are not found in animals cells, but are they found in anything other than plants?

A. I did a bit of research on this one and found that chloroplasts are also found in eukaryotic algae. I dont think eukaryotic algae classifies as a plant, however i may be wrong. josh
A. Any photosynthetic eukaryotic organism will have chloroplasts (including protista), some have a quite distinct 'cup-shaped' chloroplast. And you are right algae are not plants they belong to the Kingdom Protista. VM



Q. Speaking of organelles, what are the main differences between animal and plant cells?

A. In my oppinion (and im not a biologist so i may be wrong) the main difference is the way the plant cell gets its energy. The chloroplast is the site where sunlight is converted to glucose (i think). In an animal cell, instead of chloroplasat, we have mitochondrion which create energy n the form of ATP. So i think it is the photosynthesis that is the main difference.
The other major difference for me is what the largest organelle is in each cell. in a plant cell it is the vacuole and i think in an animal cell it is the nucleus.
again people are most certainly able to correct me or add something else. josh


These are some quality answers Josh, and vwill be very helpful. By the way, if you are in this class, you are a biologist and don't forget it! VM



Q. I am confused by the analysis section for the "designer cells" assessment task.

A. Dot point no. 4 says "Compare cell specialisation in animals and plants, as well as make insightful comments". This is what the analysis slide should address. I expect you to be able to compare and similarities between cell specialisation in animals and plants. The other section of the table is for you to comment on anything intersting at all to do with cell specialisation. It may be specific to animals or plants or be a general thing. I am leaving this open for you to decide, BUT the important thing is you have to decide on something. This is not necessarily an easy task. I am not going to give you an example but if you want suggest one, I am happy to give a one off feedback indicating whether you are on the right track.


Q. What is the fluid-mosaic model?

A. In trying to understand the structure of the plasma membrane, biologists have come up with a theory that is well supported by research. This theory is referred to as as the fluid-mosaic model. The fluid part refers to the fact that phospholipds make up the membrane but these phospholipids are in motion and able to move amongst each other (imagine a crowd of a thousand people standing at a rock concert, where people are sort of packed together but can move amonst each other, pretty good analogy hey!). The mosiac part refers to the fact that proteins are scattered amonst the phospholipids, so the membrane is not uniform in its structure. VM


Q. In the second 'pop quiz' we had, there was a question on it that asked about a water soluble substance such as an amino acid.
I still don't understand the answer... (this is where you come in) please explain!


A. In general water-soluble substances will find it difficult to get through the phopholipid layer because they mix with water but not lipids. Only very small, uncharged water soluble molecules will pass through the phospholipid bilayer, such as oxygen and carbon dioxide molecules. Amino acids are larger molecules than these and can be charged, so they will only be able to pass through the protein bits of the membrane. Now, I don't expect you to know specifically about amino acids but rather the general idea of water soluble or lipid soluble substances passing through certain parts of the membrane. VM


Just a question (i'm sure there will be more) about the beetroot prac that we did a couple of weeks ago.
Q. Was it to observe diffusion (the colour from the beetroot diffusing into the substance)?- OS

A. Well, the aim was to investigate the effect of placing beetroot cells in different environments and the fact that pigment leaked tells us that these different environments must have damaged the plasma membrane of the cells. We can say this becuase the one with water didn't have any pigment released, hence the pigment isn't able to simply diffuse out of the cells by itself. In the cases where the pigment did leak, yes you are right in saying that we could then observed the pigment spread out through the petri dish (diffusion). VM


hiii everyone :)
quick question: what else in the digestive system does absorption of nutrients occur?-GR


A. Do you mean where? It depends on what you already think. So where do you think it occurs and then I can add to that. VM
Hey GR! I am waiting for your response. Don't let it be. Questioning is crucial in developing your biolgical understanding. VM

wooops.
i was meant to say where.
the answer (i think) is that 90% of absorption occurs in the small intestine and the other 10% occurs in the large intestine. this is where all the nutrient the body needs is absorbed.

Yeah that's write GR. Pretty much all the absorption of digested material occurs along the small intestine. The large intestine is for reabsorption of water and vitamins that are made by bacteria that live there. Check your mail on the wikispace as I have also left a message there for you. VM


Q. In the area of study test, multiple choice question 6, is confusing me a lot. I answered B as it says movement of water from an area of high to an area of low concentration. The correct answer being D makes sense apart from the fact that it says from a low concentration to high concentration region of dissolved substances. What does this mean? I am confused as to how it is correct as it says from low to high concentration. Could you please explain. Thanks Adam

A. That's a good question that you have raised. When we refer to concentration we can look at it from the point of view of the water molecules or the substances dissolved in the water (solute). A low concentration of solute would represent a high concentration of free water molecules. So water will always move via osmosis from low solute concentration(high free water) to high solute concentration (low free water). Answer D is saying this. B is too vague as it is not indicating a high concentration of what, therefore it is inaccurate. In any answer involving concentration you must specifiy what you are talking about because it does matter. VM