# biology help urgent Watch

1. i have no clue how to do this question
2. Is the answer C? because that is what i got.
3. If this is a GCSE question, I think it is C as water potential is probably the energy held by the concentration of sucrose, and if that is exactly the same as the cell sap (the natural substance in the vacuole without any additional sucrose) then it would be (initial length/final length) 1/1 which equals 1. On the graph this is produced by a concentration of 0.45 mol/dm cubed
4. (Original post by Gav107)
Is the answer C? because that is what i got.
how did u do it
5. (Original post by yeah1106)
how did u do it
Basically, the x-axis shows the change in length after being in the solution. If there is no change in length, the ratio of initial length to final length will be 1.00 (If something starts at 1cm and ends at 1cm, the ratio is 1:1)

If something has the some water potential as the plant, there will be no net movement of water in or out so the length with remain the same as nothing is moving in or out to stretch or shrivel it. Because of this, you read across from the x axis where it says 1.00 and then read down to find the concentration where there is no change in size and therefore no difference in water potential.

I'm doing A2 biology at the moment so if you need anything explaining I'll do my best.
6. (Original post by scidak)
Basically, the x-axis shows the change in length after being in the solution. If there is no change in length, the ratio of initial length to final length will be 1.00 (If something starts at 1cm and ends at 1cm, the ratio is 1:1)

If something has the some water potential as the plant, there will be no net movement of water in or out so the length with remain the same as nothing is moving in or out to stretch or shrivel it. Because of this, you read across from the x axis where it says 1.00 and then read down to find the concentration where there is no change in size and therefore no difference in water potential.

I'm doing A2 biology at the moment so if you need anything explaining I'll do my best.
do u know why the answer is b to this question
7. Yes sorry i was meant to reply, but the guy who responded was right.
8. (Original post by yeah1106)
do u know why the answer is b to this question
Because uracil replaces thymine in RNA, you can figure out that C is thymine, because when uracil is present, C is not. Then because Thymine always bonds with Adenine, you look for the other column that has very similar percentages to the C column. In this case that's B so B is adenine.
9. (Original post by yeah1106)
do u know why the answer is b to this question
Were these gcse or a level questions?
10. (Original post by yeah1106)
do u know why the answer is b to this question
Surly it would have to be sample 3 because uracil is (U) found in RNA and bonded to A (adenine) in DNA. As in DNA thymine (T) is replaced by Uracil in RNA, therefore sample 3 is Adenine as it matches 25 each i.e base 3 as it has 25 matching uracil as well.
11. (Original post by Gav107)
Surly it would have to be sample 3 because uracil is (U) found in RNA and bonded to A (adenine) in DNA. As in DNA thymine (T) is replaced by Uracil in RNA, therefore sample 3 is Adenine as it matches 25 each i.e base 3 as it has 25 matching uracil as well.
The samples are samples of DNA or RNA, not bases. The letters at the top represent a nitrogenous base each, and the question asks which of these represents adenine. OP knew the answer was B anyway, and just wanted to know why.

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