Edexcel 6BIO2 ~ 3rd June 2013 ~ AS Biology

No interphase is NOT a stage in mitosis. Mitosis begins with prophase.

Thanks a lot!



I know I hope that this paper isn't as bad!

Do we need to know it?Posted from TSR Mobile

On page 36 of this thread ... There is a link and then go to page 109 in the booklet for the unit 2 mark scheme.

~ Good Luck

can someone explain the difference in reliability and validity? i always get confused

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1) Reliability refers to the confidence we can place on the measuring instrument to give us the same numeric value when the measurement is repeated on the same object.

Reliability refers to how consistent a measuring device is.


2) Validity on the other hand means that our measuring instrument actually measures the property it is supposed to measure.

Validity This refers to whether a study measures or examines what it claims to measure or examine.

thanks
for one question it says why are all the seeds kept at same temperature? in the mark scheme it stated that temperature is a variable, needs to be controlled to ensure results are reliable.
in another question it says why are seeds taken from the same plant? mark sheme says reduces genetic variation to ensure results are valid.
i would have also put valid for first queestion but would have not got that mark, i dont get why its different in thia case?

I have actually only started revision 3 days ago, but im surprised how well it is going. Notes here are fantastic, they help alot.
I have done 3 Past Papers so far. In the first one i had 55/80, second one 63/80. and third one 65/80. So i am improving and its going great. Kinda getting the technique to answer these questions and alot of questions in papers are repetitive imo. How are you guys going with PP's how are you scoring?

Validity refers to the technique and apparatus used for collecting the data .

thanks

When a question asks you to describe the relationship between 2 things, mark scheme awards a mark for manipulating data, how do i correctly manipulate the data.

January 2011, question 2b)iv) For this question i have stated the overall trend (There is positive correlation between the two things), then i have said that at 400mg it is 6 units and at 800mg it is 12.5units, this is a difference of 6.5 units.
Is this the correct way to manipulate data????

In a simple answer yes you've manipulated the data to prove your point

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basically, tumour suppressor genes are responsible for telling the cell cycle to stop, so don't make new proteins, or divide. If the tumor supressor gene is faulty, it won't be able to carry it out it's function which is marking point 3. And if it's not able to control division, then you know the cell cycle will occur faster (in less time) as it won't have to stop ~ marking point 2. Because it's faster as a whole, mitosis is faster, and interphase will be faster (marking point 1), and finally, because the whole thing is happening so fast and uncontrollably, the cells aren't able to specialise, as they presumabely start to go through the cell cycle, as there's nothing to tell it not too..

hope this helps, if not, let me know

So whenever there is a question which asks to describe the data, i can take two numbers away???