.

[andrewloppol]

.

[stonecold]

did the experiment last week and had 30 min SAC questions on it last night.
am pretty confident. 

we just used cellulose tubing and a solution containing starch, protein, NaCl and glucose....and we put it in a beaker full of de-ion water with one of those flea-stirrer things to keep the conc. gradient high.

[stonecold]

umm, our teacher isn't following the textbook exactly.
she taught us about the organelles and phospholipid bilayer.  last night we did lipids and carbohydrates.  next week is proteins and nucliec acids.  nice and easy if you do chem.

[stonecold]

^ you mean like glycerol and fatty acids and condensation reactions?
we've done that.  we also did hexoses and pentoses last night.
we made glucose molecules with those chemistry sets and then we joined with another group and made manose lol.....

[akira88]

Yes I've done my membrances SAC already, got 24/25
Not sure where I stuffed up but I hopefully can have a look at it sometime soon...
I think my biology class is going so sloooowly, and the teacher doesn't even "teach". She's very pro about "self-directed learning", where we do the questions ourselves and "self-correct" using these sheets. I don't do it. Lmao too lazy. All she does is sit pretty in front of the class fiddling with her laptop T___T

[stonecold]

i already know like half of them...yay! i <3 bio....
and the other half i read them on the holidays but i sorta forget them haha.

and yeah i agree. pretty easy to teach yourself.  but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

[akira88]

Yes I've done my membrances SAC already, got 24/25
Not sure where I stuffed up but I hopefully can have a look at it sometime soon...
I think my biology class is going so sloooowly, and the teacher doesn't even "teach". She's very pro about "self-directed learning", where we do the questions ourselves and "self-correct" using these sheets. I don't do it. Lmao too lazy. All she does is sit pretty in front of the class fiddling with her laptop T___T

Self directed learning :O?
Duuude..
Year 12 at school is all about spoon feeding . Getting given the answers on a sheet is good though!
Night time is for self directed!
Lazy teacher lol.
Bio's pretty easy to learn solo anyway, it's not very hard to understand! (There are a few hiccups though.)

I'm so glad that you can read from the Biology textbook and learn the content though, so phew! Yup I know... self directed learning T__T

but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

I'm glad I had another teacher explain to me that the textbooks aren't necessarily 100% true, and he told me about that

[lexitu]

Our class is doing a practical SAC using beetroot to explore our understanding of membranes. The main thing that we need to understand is why the solution (that the beetroot was placed in) changed colour.

So here are the different solutions: distilled water, pH 4, pH 7, pH 9.2, alcohol 1%, alcohol 25%, alcohol 50%, detergent 1%, detergent 5%.

Separate to this the beetroot was placed in temperatures of 0,10,25,40,50,60,70 degrees.

The results indicated that alcohol and detergent cause most pigment leakage (about 3-4/5 on a scale). Varying pH had a small effect, as did distilled water (about 2-3/5).

One interesting result was that pH 9.2 resulted in a colour leakage rating of 1 after 30 mins then change to 0 after 24 hours. What is an explanation for this?

For temperature, the colder, the more leakage and the warmer, also the more leakage. Temperatures 25 and 40 both showed little to no colour loss.

How do you explain these results?

[slothpomba]

Mine was similar to stone colds.

Dialysis tubing was featured in all 3 experiments.

We only performed one ourselves and the other two were done as demonstrations due to time constraints and the gas not functioning because of the construction.

Experiment 1: Place a dialysis tube full of starch in a beaker full of water and Iodine solution.  Leave for 30 minutes. (there may of been some heat involved.

Result: After 30 minutes the contents inside the dialysis tubing bag turned purple (indicating starch). This also proves that while iodine and water solution moved into the bag, hence reacting with the contents, no change was observed in the water outside the bag. This is because almost no starch made it through the dialysis tubing due to its size, while water solutions could fit through.
Experiment 2: Cut ~10 chunks of potato as equally as you can, place 2 into a cup, this way filling 5 cups. Label each cup 0%, 0.5% 1% 2% 5%. Weigh the potato contents of each cup and record.  Fill each cup with matching concentration of NaCl (Salt water) and in the case of the 0% cup distilled water.

Leave for 30 minutes.

Remove and weigh the potato slices using the same procedure as before.

Figure out the change in weight, in absolute value and % wise.

Results: Cant remember exactly but the 0, 0.5, gained weight by a relative big amount. 1% barely changed with a little weight gain. 2% and 5% showed weight loss.

This can be explained by osmosis and the osmotic pressure causing water loss.
Experiment 3: ... if i remember ill write back.

[akira88]

i already know like half of them...yay! i <3 bio....
and the other half i read them on the holidays but i sorta forget them haha.

and yeah i agree. pretty easy to teach yourself.  but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

Root cells, for example, aren't exposed to sunlight, so it's really inefficient (waste of resources) to have chloroplasts in there.

Yes I've done my membrances SAC already, got 24/25
Not sure where I stuffed up but I hopefully can have a look at it sometime soon...
I think my biology class is going so sloooowly, and the teacher doesn't even "teach". She's very pro about "self-directed learning", where we do the questions ourselves and "self-correct" using these sheets. I don't do it. Lmao too lazy. All she does is sit pretty in front of the class fiddling with her laptop T___T

Self directed learning :O?
Duuude..
Year 12 at school is all about spoon feeding . Getting given the answers on a sheet is good though!
Night time is for self directed!
Lazy teacher lol.
Bio's pretty easy to learn solo anyway, it's not very hard to understand! (There are a few hiccups though.)

I'm so glad that you can read from the Biology textbook and learn the content though, so phew! Yup I know... self directed learning T__T

but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

I'm glad I had another teacher explain to me that the textbooks aren't necessarily 100% true, and he told me about that

There is also a bit more to learn than just the textbooks!
E.g Cell membranes possess CHOLESTEROL for maintaining fluidity and stability!
That was on the exam last year, but don't remember reading it in Nature of Biology lol.

Oh what?! That's strange because the cholesterol in membranes was mentioned many times in Heinemann... and also in its workbook
Yeah I'm trying to hopefully get more resources for biology so I can go well

[akira88]

Mine was similar to stone colds.

Dialysis tubing was featured in all 3 experiments.

We only performed one ourselves and the other two were done as demonstrations due to time constraints and the gas not functioning because of the construction.

Experiment 1: Place a dialysis tube full of starch in a beaker full of water and Iodine solution.  Leave for 30 minutes. (there may of been some heat involved.

Result: After 30 minutes the contents inside the dialysis tubing bag turned purple (indicating starch). This also proves that while iodine and water solution moved into the bag, hence reacting with the contents, no change was observed in the water outside the bag. This is because almost no starch made it through the dialysis tubing due to its size, while water solutions could fit through.
Experiment 2: Cut ~10 chunks of potato as equally as you can, place 2 into a cup, this way filling 5 cups. Label each cup 0%, 0.5% 1% 2% 5%. Weigh the potato contents of each cup and record.  Fill each cup with matching concentration of NaCl (Salt water) and in the case of the 0% cup distilled water.

Leave for 30 minutes.

Remove and weigh the potato slices using the same procedure as before.

Figure out the change in weight, in absolute value and % wise.

Results: Cant remember exactly but the 0, 0.5, gained weight by a relative big amount. 1% barely changed with a little weight gain. 2% and 5% showed weight loss.

This can be explained by osmosis and the osmotic pressure causing water loss.
Experiment 3: ... if i remember ill write back.

My SAC was like your experiment 2, with potato cylinders and but we had 10% NaCl solutions as well XD

[stonecold]

i already know like half of them...yay! i <3 bio....
and the other half i read them on the holidays but i sorta forget them haha.

and yeah i agree. pretty easy to teach yourself.  but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

Root cells, for example, aren't exposed to sunlight, so it's really inefficient (waste of resources) to have chloroplasts in there.

Yes I've done my membrances SAC already, got 24/25
Not sure where I stuffed up but I hopefully can have a look at it sometime soon...
I think my biology class is going so sloooowly, and the teacher doesn't even "teach". She's very pro about "self-directed learning", where we do the questions ourselves and "self-correct" using these sheets. I don't do it. Lmao too lazy. All she does is sit pretty in front of the class fiddling with her laptop T___T

Self directed learning :O?
Duuude..
Year 12 at school is all about spoon feeding . Getting given the answers on a sheet is good though!
Night time is for self directed!
Lazy teacher lol.
Bio's pretty easy to learn solo anyway, it's not very hard to understand! (There are a few hiccups though.)

I'm so glad that you can read from the Biology textbook and learn the content though, so phew! Yup I know... self directed learning T__T

but there a some things you need to be told.  i.e. most textbooks don't really mention that not all plant cells have chloroplasts!

I'm glad I had another teacher explain to me that the textbooks aren't necessarily 100% true, and he told me about that

There is also a bit more to learn than just the textbooks!
E.g Cell membranes possess CHOLESTEROL for maintaining fluidity and stability!
That was on the exam last year, but don't remember reading it in Nature of Biology lol.

Oh what?! That's strange because the cholesterol in membranes was mentioned many times in Heinemann... and also in its workbook
Yeah I'm trying to hopefully get more resources for biology so I can go well

damn textbooks! heinemann talks about cholesterol in the membrane but doesn't mention anything about aquaporins.  

[akira88]

Aquaporins are relatively new though aren't they? Something like 2003 or so?
I doubt examiners will examine it though, due to many teachers lacking the knowledge of the discovery and not teaching it?

Biol textbooks will have to be re-written!

I know they have to be re-written!
LOL Andrew Douch's podcasts, I fell asleep during the first half of his podcast on enzymes as he attempted to use PacMan as an analogy for enzymes....

[TrueLight]

aqua porins are just small water protein channels that span the whole membrane ....so yeah i don't think you guys need to learn about them specifically, but i think from bad memory...that you have to know the structure and function of the cell membrane
lol pacman......

[TrueLight]

yep