How was Biology Paper 5?

[deathvalley]

the second question was so easy , the first one does require a lot thinking

 

[Umarfb]

I said, to find the water potential OF THE TISSUE, draw a line of best fit through the plotted points on graph and at the conc of x-intercept( rate=0 ) the water potential of sucrose equals that of cells... And yeah it was t-test...! But i don't expect the gt to b above 20...! PAPER surely gave us hard time duhh!

 

[beacon_of_light]

And didn't we have to explain or discuss abt the other points above or below x-axis ?

 

[Newbie]

I was such an a** .... I couldn't remember the word plasmolysed and wrote shrink and what not .... I just couldn't remember the word ... damn .. I hate my self :x :x :x :fool: :fool: :fool:

I wonder if examiner will accept my word "shrink" and the diagram :Yahoo!:

 

[honeycoveredcookie]

Oh, and one more thing.
It asked us how we can determine the water potential of the plant tissue.

I said that we should keep them all in distilled water for around 20 minutes, and then look at the under the microscope to see whether they're all uniformly turgid.
At the start of my experiment too, I mentioned that all the plant tissues must be first kept in distilled water for around 15 minutes so that they have similar water potential so that the results are accurate when measuring the water potential for sucrose.

You'll get points for mentioning the need to equilibrate the plant tissues to the same water potential, I didn't mention that. As for the oocytes. The hypothesis was testing the effect of the activator compound on the maturation of immature oocytes and in order to keep them immature, you cannot let them move on to the secondary stage, else meiosis would start and using the compound wouldn't matter much.

It didn't ask us how to determine the water potential, it asked us how to estimate it, which gives a clearly different meaning. On the graph, there will be a point where the line cuts the x-axis, which would mean the diffusion of the droplet is zero at that point. That point would correspond to a certain sucrose concentration and it would mean the water potential of the sucrose solution and the plant tissue are the same at that point. So, we can use that particular concentration of sucrose and find its water potential to estimate the water potential of the plant tissue.

Also, the specific term is not flaccid, it is Plasmolysed

Yupp. I'll get marks for the oocyte thing. I wrote things along those lines.

Okay, so the water potential is going for a toss. Losing 2 marks there.

What's the exact definition for standard error? I said that its the amount that the number can vary about the mean without being due to any significant reason (due to chance.)

DAAAAAAAAAAMN. Plasmolysed. I didn't think of it. UGH.

Hmm. I hope I don't lose more than 7 - 8 marks over all. Just hope the GT isn't too high. -.-

 

[nisurju]

what is the hypothesis?
and what does the value of the table suggest??

 

[honeycoveredcookie]

This is what I wrote for the long experiment procedure.
1. Make up 6 solutions of sucrose (with the conc that was mentioned). Make up 6 more sucrose solutions of the same concentration.
2. Keep all the solutions in test tubes in a water bath regulated at around 25 degrees C.
3. Cut up 6 pieces of plant tissue with the same dimensions each and place them in distilled water for 15 minutes.
4. Take all the tissue out after 15 minutes and place one of them into the 0.00 dm3 sucrose solution for 10 minutes.
5. Use a pipette to draw some of the solution out of the solution with the plant tissue, and release one drop into the test tube with just sucrose solution at the same concentration.
6. Start the stop watch.
7. Stop the stop watch once the drops reaches the bottom of the test tube.
8. Time taken is used to measure the rate by 1 / time.
9. Repeat this 3 more times to remove anomalies and obtain accurate results.
10. Repeat the entire investigation with different concentrations of sucrose solution.
11. At (i dont remember the exact conc) the droplet will start to move upwards due to a great decrease in density as the water potential of the sucrose solution is the high.
12. It is a low risk experiment.
13. Ensure that the volume of sucrose in each test - tube is constant.
14. Ensure that the droplets are all the same size.

I wrote some other junk too. Can't remember it all now though.

 

[MukeshG93]

Oh, and one more thing.
It asked us how we can determine the water potential of the plant tissue.

I said that we should keep them all in distilled water for around 20 minutes, and then look at the under the microscope to see whether they're all uniformly turgid.
At the start of my experiment too, I mentioned that all the plant tissues must be first kept in distilled water for around 15 minutes so that they have similar water potential so that the results are accurate when measuring the water potential for sucrose.

You'll get points for mentioning the need to equilibrate the plant tissues to the same water potential, I didn't mention that. As for the oocytes. The hypothesis was testing the effect of the activator compound on the maturation of immature oocytes and in order to keep them immature, you cannot let them move on to the secondary stage, else meiosis would start and using the compound wouldn't matter much.

It didn't ask us how to determine the water potential, it asked us how to estimate it, which gives a clearly different meaning. On the graph, there will be a point where the line cuts the x-axis, which would mean the diffusion of the droplet is zero at that point. That point would correspond to a certain sucrose concentration and it would mean the water potential of the sucrose solution and the plant tissue are the same at that point. So, we can use that particular concentration of sucrose and find its water potential to estimate the water potential of the plant tissue.

Also, the specific term is not flaccid, it is Plasmolysed

Yupp. I'll get marks for the oocyte thing. I wrote things along those lines.

Okay, so the water potential is going for a toss. Losing 2 marks there.

What's the exact definition for standard error? I said that its the amount that the number can vary about the mean without being due to any significant reason (due to chance.)

DAAAAAAAAAAMN. Plasmolysed. I didn't think of it. UGH.

Hmm. I hope I don't lose more than 7 - 8 marks over all. Just hope the GT isn't too high. -.-

DW about the standard error, you got it right and 'sides, it was just a mark. It also measures the reliability (unreliability) of the data

 

[shahzaibbajwa]

After going through all these posts, I have realized that I did well. Hoping to get a good score here.
and how did everyone's P22 go? I took both AS and A2 together. It was damn easy.

 

[honeycoveredcookie]

what is the hypothesis?
and what does the value of the table suggest??

The null hypothesis was that that compound that they mentioned has no effect on the mean rate of meiosis.

 

[honeycoveredcookie]

DW about the standard error, you got it right and 'sides, it was just a mark. It also measures the reliability (unreliability) of the data

Oh goody. I just scraped an A in As. 80%. If this paper goes bad, i'm afraid it might upset my grade. -.- Paper four better be good.

 

[MukeshG93]

This is what I wrote for the long experiment procedure.
1. Make up 6 solutions of sucrose (with the conc that was mentioned). Make up 6 more sucrose solutions of the same concentration.
2. Keep all the solutions in test tubes in a water bath regulated at around 25 degrees C.
3. Cut up 6 pieces of plant tissue with the same dimensions each and place them in distilled water for 15 minutes.
4. Take all the tissue out after 15 minutes and place one of them into the 0.00 dm3 sucrose solution for 10 minutes.
5. Use a pipette to draw some of the solution out of the solution with the plant tissue, and release one drop into the test tube with just sucrose solution at the same concentration.
6. Start the stop watch.
7. Stop the stop watch once the drops reaches the bottom of the test tube.
8. Time taken is used to measure the rate by 1 / time.
9. Repeat this 3 more times to remove anomalies and obtain accurate results.
10. Repeat the entire investigation with different concentrations of sucrose solution.
11. At (i dont remember the exact conc) the droplet will start to move upwards due to a great decrease in density as the water potential of the sucrose solution is the high.
12. It is a low risk experiment.
13. Ensure that the volume of sucrose in each test - tube is constant.
14. Ensure that the droplets are all the same size.

I wrote some other junk too. Can't remember it all now though.

WHOA, that's really something! Nice going! I mentioned keeping the temperature and the pH constant (using a thermostatically controlled water bath and using a Phosphate buffer) I also mentioned using more concentrations for accuracy and repeating the procedure at the same concentrations for reliability. Missed out on a lot of stuff you put up, good job! Yeah, low risk is a cheap mark. I mentioned how to serially dilute and explained what volumes are to be used to prepare solutions of 0.8 and 0.6 mol/dm3 and mentioned the use of pure water for the 0.0 mol/dm3. Meh, overall I expect a 6 - 7, but I wish CIE'd surprise me with an A* overall, I had gotten a 85 for my AS.

 

[honeycoveredcookie]

This is what I wrote for the long experiment procedure.
1. Make up 6 solutions of sucrose (with the conc that was mentioned). Make up 6 more sucrose solutions of the same concentration.
2. Keep all the solutions in test tubes in a water bath regulated at around 25 degrees C.
3. Cut up 6 pieces of plant tissue with the same dimensions each and place them in distilled water for 15 minutes.
4. Take all the tissue out after 15 minutes and place one of them into the 0.00 dm3 sucrose solution for 10 minutes.
5. Use a pipette to draw some of the solution out of the solution with the plant tissue, and release one drop into the test tube with just sucrose solution at the same concentration.
6. Start the stop watch.
7. Stop the stop watch once the drops reaches the bottom of the test tube.
8. Time taken is used to measure the rate by 1 / time.
9. Repeat this 3 more times to remove anomalies and obtain accurate results.
10. Repeat the entire investigation with different concentrations of sucrose solution.
11. At (i dont remember the exact conc) the droplet will start to move upwards due to a great decrease in density as the water potential of the sucrose solution is the high.
12. It is a low risk experiment.
13. Ensure that the volume of sucrose in each test - tube is constant.
14. Ensure that the droplets are all the same size.

I wrote some other junk too. Can't remember it all now though.

WHOA, that's really something! Nice going! I mentioned keeping the temperature and the pH constant (using a thermostatically controlled water bath and using a Phosphate buffer) I also mentioned using more concentrations for accuracy and repeating the procedure at the same concentrations for reliability. Missed out on a lot of stuff you put up, good job! Yeah, low risk is a cheap mark. I mentioned how to serially dilute and explained what volumes are to be used to prepare solutions of 0.8 and 0.6 mol/dm3 and mentioned the use of pure water for the 0.0 mol/dm3. Meh, overall I expect a 6 - 7, but I wish CIE'd surprise me with an A* overall, I had gotten a 85 for my AS.

Low risk is a joke. Haha.

85, then A* shouldn't be that hard. Work hard for paper 4.
Chem is just simply killing me. Haha.

A* is practically impossible if you get just 80% in As.

 

[MukeshG93]

And didn't we have to explain or discuss abt the other points above or below x-axis ?

Not for the water potential of the plant tissues we didn't. We, however, had to discuss them when it came to the comparison between the 0.2 mol/dm3 and 0.8mol/dm3 solutions' effects on the plant cells. I even labelled the nucleus and the vacuole along with the cell wall and cytoplasm (LOL)

 

[honeycoveredcookie]

And didn't we have to explain or discuss abt the other points above or below x-axis ?

Not for the water potential of the plant tissues we didn't. We, however, had to discuss them when it came to the comparison between the 0.2 mol/dm3 and 0.8mol/dm3 solutions' effects on the plant cells. I even labelled the nucleus and the vacuole along with the cell wall and cytoplasm (LOL)

I didn't mention the graph when answering that question. I just answered whether the water would move from the cell to the sucrose, or vice versa due to a water potential gradient and stuff. :/

 

[MukeshG93]

Yeah, you'll have to get a 100% or more (uniform %-wise) to get an A* now and I ain't hoping for it. My bio is bad, after it hit A2, my straight topping streaks in Bio dropped to a dead-end, but I will try. P4 is a pain. I got a 90% in Chemistry in AS, I think I can pull an A*, I am pro at P4 (Rhyme intended). Meh, I just hope the P5s go well, that's all, cuz, personally, I'm not much of a practical guy, it's all theory for me.

 

[MukeshG93]

And didn't we have to explain or discuss abt the other points above or below x-axis ?

Not for the water potential of the plant tissues we didn't. We, however, had to discuss them when it came to the comparison between the 0.2 mol/dm3 and 0.8mol/dm3 solutions' effects on the plant cells. I even labelled the nucleus and the vacuole along with the cell wall and cytoplasm (LOL)

I didn't mention the graph when answering that question. I just answered whether the water would move from the cell to the sucrose, or vice versa due to a water potential gradient and stuff. :/

I didn't mention the graph either, I was just saying the values would be used for reference to oneself, not in the exam, lol. We had like 3 lines, who would mention the graph for the explanation?

 

[honeycoveredcookie]

I did so badly in Chem As that I'm repeating it again this year. Haha.
Hoping for an A, but its almost impossible for me.
I screwed up As practicals this time. Paper 5 was fine, like Bio. Paper 2 I expect an A. Paper 4 next week i HAVE to kill. PLEASE give me tips.

 

[honeycoveredcookie]

Okay thank goodness. You almost scared me.

 

[beacon_of_light]

And didn't we have to explain or discuss abt the other points above or below x-axis ?

Not for the water potential of the plant tissues we didn't. We, however, had to discuss them when it came to the comparison between the 0.2 mol/dm3 and 0.8mol/dm3 solutions' effects on the plant cells. I even labelled the nucleus and the vacuole along with the cell wall and cytoplasm (LOL)

I didn't explain the graph in those 3 lines... lol But I discussed the graph in the experiment ... just to show what the other points apart from the one on x-axis meant...