Joker37

Hi everybody, What can a general 3 year science degree majoring in Biochemistry lead to? What sort of jobs are available to people after completing this type of degee? Would honours increase your employment prospects considerably? If so, how so? Should you get industrial experience before moving onto a phD if that is what you plan to do? Is it wise to do a double major?

When will petroleum engineers become redundant due to low oil recovery because of depleting amounts of oil throughout the world? At what year will getting a degree in petroleum engineering be not worth it? A close friend of mine is interested in become a petroleum engineer and I am asking here because I am curious too, if anyone knows or has any ideas...

Is this true? I keep hearing this everywhere. If so, what are the root causes for the higher proportion of women to be on this planet than men? Thanks

For how long have humans known of any of the negative effects of alcohol consumption on the human body? As most people are aware today, alcohol is a poison. It can cause cancer (http://ama.com.au/node/6639), someone to go into a comber or even death. My question, were many of the negative effects of alcohol consumption known say 1000 years ago? Or have most of them only been discovered recently? If so, what's the earliest recorded observations of the negative effects of alcohol consumption on the human body? I ask because I am interested in knowing whether the negative effects of alcohol consumption have only recently been discovered (i.e. similar to smoking). Thanks

What does everybody think? Also, do the benefits in polygamy outweigh the benefits in monogamy? Which one is better?

Can you provide any sources for your claim?

How does a computer get an infection from internet usage? And iff you did get a virus, trojan etc...would you be able to know which website the virus/trojan came from? How would I do this if I wanted to find out? Is there a way?

A student titrated an aliquot of standard sodium carbonate solution with hydrochloric acid in a burette. State whether the concentration determined for the hydrochloric acid would be likely to be higher, lower or unchanged compared with the actual value if the student had previously washed with water, but not dried, the following apparatus: a)the pipette used to deliver the aliquot of sodium carbonate solution b)the flask containing the aliquot c)the burette. Any help with the reasoning/explanation/walkthrough of the above question will be greatly appreciated! :)

What does everyone think? What's the most recent scientific data suggesting? At what age should we humans be making babies as to reduce complications/birth defects? And generally, is the human population reproducing babies at a significantly older age compared to the ideal age?

I was just curious, heard that the Islamic version of holy water (from Mecca - think it's call zam zam or something along those lines) had high levels of arsenic. In general is holy water any different than regular water? Has the use of holy water been associated with any supernatural phenomena (e.g. in the Bible or in real life)?

I heard that animals are disappearing faster and faster thanks to global warming. But how fast is this extinction rate estimated to be? How many animals are going extinct because of global warming? Anybody know?

What makes dogs loyal to humans? Is it based on hereditary information or environmental factors? Please provide examples from everyday life with your stance.

Thanks for telling me! Definitely gonna read the whole thread and most (if not all) the links within. :)

Hi everybody! I am thinking of doing an oral for school to persuade people that whaling is legitimate and should continue. I am wondering whether anybody would be able to give me some rough points to include for my arguments or refer me to any sites/resources that may be of use to me. I am also curious whether there are any movies (or even documentaries) about whaling out there that I could watch? Any help would be appreciated! :rolleyes: And I am also curious what everyone thinks? Should whaling be illegal? Is there no right or wrong answer?

Is it true that Israel is racist? In what ways is it racist? I keep hearing that it's racist but don't know how.

Chemically speaking, what's the difference between holy water and regular water? Have there been any recent scientific investigations on this?

The potato discs which gained mass were put in a hypotonic sucrose solution. Because there was a higher concentration of sucrose molecules within the potato cells a net movement of water molecules was observed coming into the potato cells in an attempt to maintain an equilibrium position between the concentrations of sucrose within and outside the potato cells. The potato discs which lost mass were put in a hypertonic sucrose solution. Because there was a higher concentration of sucrose molecules outside the potato cells a net movement of water molecules was observed coming out of the potato cells in an attempt to maintain an equilibrium position between the concentrations of sucrose within and outside the potato cells.

Also, what could be a variable and a limitation to this experiment?

Also, is it legitmate to assume that all the potato discs which gained mass were placed in a hypotonic sucrose solution? (and hence became turgid) And those that loss mass were put in a hypertonic sucrose environment? (a thus became more flaccid)

is it just because of the net movement of water molecules that are responsible for the change in mass of the potato discs? ok just made up some rough random answers...don't really know the answers. what are should have i said?!? Using 15 petri dishes would have taken far too long. Using 2 petri dishes wouldn't have sufficiently eliminated outlying measurements. ? The sucrose cannot pass through a semi-permeable cell membrane because it is too big of a molecule to do so and because of this any change in mass in the potato discs must be due to net movement of water molecules either entering or leaving the potato cells through the process of osmosis. Ethyl alcohol can pass through the semi-permeable membrane of a potato cell and therefore if this was used instead of sucrose it wouldn't be clear whether any osmosis did occur. The purpose of this experiment was to investigate the effects of osmosis in potato cells placed in varying concentrations of sucrose. Usage of ethyl alcohol instead of sucrose places doubts on the extent of osmosis and hence sucrose solution is best to be used. The skin from the potato cylinders may not allow the passage of water into or out of potato cells and hence had to be removed. This ensures that the processes of osmosis can be undertaken in the experiment and thus the validity of the method. Thinner potato discs means a larger surface area-to-volume ratio. This means more water molecules per unit time will be able to move into or out of the potato discs. Essentially, the more slices that are weighed than the more reliable the measurements are going to be due to the reduction of random errors and outlying data (e.g. because of oddly cut potato discs). However at the same time cutting 35 slices would have taken far too long and made the task far more tedious where experimentors would have been more likely to become more prone to make mistakes. On the otherhand if only 2 slices of potato discs were weighed then outlying data may not have got accounted for and thus extreme values from either ends of the scale could have been recorded, leading to inaccuracies.

Does the hypothesis have to be written down in past tense? I heard that it does but just want to make sure.

Also, I was wondering whether people could help make me more questions for the discussion and then I could probably make up answers to them. I've also been told that my class will actually be tested on the experiment with a bunch of questions regarding the activity some time next week. So, it would definitely help me a lot in preparing if people could post up some more questions (as much as possible if you can). Thanks again to the people who made a post in this thread! Very helpful and I appreciate it all.

Also, does anyone know which of the potato discs should have gained the highest percentage mass change? And, would any be expected to lose mass? (i.e. the potato discs which were put in 0.1 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, 1.0 M sucrose solutions or the distilled water) I just want to check whether my results are consistent with what's expected. And if they're not then I could probably try finding reasons for why they're not consistent. Thanks

Thanks for the help so far! Really appreciate it Rade. Thanks. :) Also, while we're at it do you know what the difference is between a discussion and a conclusion in a typical biology practical report? I have to go somewhere now but I'll definitely be making some extra questions for my practical report later.

Hi there everybody! My biology class has just completed a practical activity on osmosis. I am supposed to write a practical report for the experiment however my teacher didn't give us any questions and I have to build up by discussion page so that my report will be lengthy, so I am wondering whether anyone would be able to provide me with questions that I could put in the practical report to include, answer and consider myself. Below is what was written on my practical sheet for the experiment. Any help/guidance from you biologists for this activity would be much appreciated and I would be eternally grateful if anyone could help me with things to think about the experiment and any complexities I need to think/consider and put in my practical report. It seems like a pretty simple experiment just involving the placement of potato discs in different sucrose concentrations for 30 mins and recording the changes in mass. What are the expected changes in mass of the potato discs that were put in a lower concentration of sucrose compared to the ones which were put in a higher concentration of sucrose? What do you guys think? Is this a common biology experiment by the way? Anyway, I emphasize any assistance would be highly appreciated! Introduction: This activity focuses on osmosis and the effect of different concentrations of sucrose solutions on plant (potato) cells. All substances passing into a cell have to move through a plasma membrane. The plasma membrane is partially permeable. Movement can occur via a number of processes including diffusion. Materials: Fresh potato Scalpel Plastic ruler Petri dishes Measuring cylinder Distilled water Sucrose solutions – 0.1M, 0.2M, 0.4M, 0.6M, 0.8M, 1M Paper towelling Tweezers Electronic balance Felt pen Method: 1. Label 7 Petri dishes (on lids) with the concentrations of sucrose solution. 2. (A cylinder of potato has been cut for you). Trim the ends flat so that no skin is left. Slice into 1-2 mm slices. You need 70 slices of potato for your group. Using tweezers make 7 groups of 10 slices- place gently on paper towel. 3. Weigh the first ten slices. Record the total mass of these ten slices in a table. 4. Place these ten slices into Petri dish 1 and cover slices with 30 mL sucrose solution of 0.1M. Cover dish with labelled lid and leave 30 minutes at room temperature. 5. Repeat procedure for remaining concentrations of sucrose and distilled water. 6. Carefully remove the ten slices from 0.1M solution and place on paper towel. Gently dab the top of slices to remove excess solution. Transfer to new towel when weighing. 7. Weigh the ten slices and record the mass in your table. 8. Repeat for the remaining dishes. Discard potato and clean up. 9. Calculate the change in mass and record findings in your table. 10. Also calculate the percentage increase or decrease in mass and place answers in the third column in the table. 11. Graph results (sucrose concentration x axis, %change in mass y axis). Remember you may have positive and negative changes and thus your y axis should allow for this. The graphs should be a line of best fit graph – in pencil. Remember to fully label the axes and give the graph a heading.