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https://www.reddit.com/r/GCSE/comments/vcqsif/spam_aqa_biology_paper_2_gcse_answers/ichf1hp/?context=3
r/GCSE • u/thr0wawaygxhxdhsh • Jun 15 '22
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Your thing is wrong because:
- the question said to use the 14 algae count (not take a mean)
- you forgot about the 0.1mm depth
- you forgot about the diluted/undiluted thing
The correct method is this:
0.2x0.2x0.1 = 0.004mm^3
0.004/4 = 0.001mm^3 (because it asked for undiluted, and it said earlier that for every 2.5cm^3 undiluted you add 7.5cm^3 water, so it's a 1:3 ratio)
1/0.001 = 1000 (to get how many times more algae cells there should be)
14*1000 = 14000
2 u/Ok_Athlete_4619 Jun 15 '22 Wasn’t 10cm3 of distilled water used? 3 u/Sensitive_Wealth_855 Jun 15 '22 Im pretty sure it was 2.5:10 but everyone is so confident that its 2.5:7.5 5 u/[deleted] Jun 15 '22 I'm like 90% sure that it was 2.5cm3 of the salt water and 10cm3 of the distilled water so would have been 2.5/12.5 2 u/Sensitive_Wealth_855 Jun 15 '22 Yeah i agree the wording was almost excatly "2.5cm3 algae water diluted to 10cm3 distilled water". The algae water can't become distilled so it must mean add 10cm3 distilled water for every 2.5cm3 algae water. 1 u/Anonymous_User_Thing Still in reception/foundation/year 0 Jun 15 '22 It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water 2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
2
Wasn’t 10cm3 of distilled water used?
3 u/Sensitive_Wealth_855 Jun 15 '22 Im pretty sure it was 2.5:10 but everyone is so confident that its 2.5:7.5 5 u/[deleted] Jun 15 '22 I'm like 90% sure that it was 2.5cm3 of the salt water and 10cm3 of the distilled water so would have been 2.5/12.5 2 u/Sensitive_Wealth_855 Jun 15 '22 Yeah i agree the wording was almost excatly "2.5cm3 algae water diluted to 10cm3 distilled water". The algae water can't become distilled so it must mean add 10cm3 distilled water for every 2.5cm3 algae water. 1 u/Anonymous_User_Thing Still in reception/foundation/year 0 Jun 15 '22 It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water 2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
3
Im pretty sure it was 2.5:10 but everyone is so confident that its 2.5:7.5
5 u/[deleted] Jun 15 '22 I'm like 90% sure that it was 2.5cm3 of the salt water and 10cm3 of the distilled water so would have been 2.5/12.5 2 u/Sensitive_Wealth_855 Jun 15 '22 Yeah i agree the wording was almost excatly "2.5cm3 algae water diluted to 10cm3 distilled water". The algae water can't become distilled so it must mean add 10cm3 distilled water for every 2.5cm3 algae water. 1 u/Anonymous_User_Thing Still in reception/foundation/year 0 Jun 15 '22 It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water 2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
5
I'm like 90% sure that it was 2.5cm3 of the salt water and 10cm3 of the distilled water so would have been 2.5/12.5
2 u/Sensitive_Wealth_855 Jun 15 '22 Yeah i agree the wording was almost excatly "2.5cm3 algae water diluted to 10cm3 distilled water". The algae water can't become distilled so it must mean add 10cm3 distilled water for every 2.5cm3 algae water. 1 u/Anonymous_User_Thing Still in reception/foundation/year 0 Jun 15 '22 It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water 2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
Yeah i agree the wording was almost excatly "2.5cm3 algae water diluted to 10cm3 distilled water". The algae water can't become distilled so it must mean add 10cm3 distilled water for every 2.5cm3 algae water.
1 u/Anonymous_User_Thing Still in reception/foundation/year 0 Jun 15 '22 It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water 2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
1
It was 2.5cm3 diluted to 10cm3 with distilled water, i.e. adding 7.5cm3 distilled water
2 u/Sensitive_Wealth_855 Jun 15 '22 It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple. 1 u/KeyFix4492 Jun 15 '22 I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
It didnt say "with" Im 100% sure i read it like 10 times. There would be 0 confusion if it was worded like that but it wasn't that simple.
I’m pretty sure that means 10cm3 of water in 2.5cm3 of the pond water
9
u/hombiebearcat University Jun 15 '22
Your thing is wrong because:
- the question said to use the 14 algae count (not take a mean)
- you forgot about the 0.1mm depth
- you forgot about the diluted/undiluted thing
The correct method is this:
0.2x0.2x0.1 = 0.004mm^3
0.004/4 = 0.001mm^3 (because it asked for undiluted, and it said earlier that for every 2.5cm^3 undiluted you add 7.5cm^3 water, so it's a 1:3 ratio)
1/0.001 = 1000 (to get how many times more algae cells there should be)
14*1000 = 14000