GCSE Biology OCR 21st century B4,5,6. 9th June 2017

Original post by samwesttt

Memory (2) I talked about forming neural pathways and the ability to recall memories. I also talked about how it enables us to remember how to perform skills.
Starfish (6) I basically defined how the human nervous system works and then compared it to the starfish. Similarities; the receptor that detects the stimuli, I said it was sort of similar that there is a nerve that links the receptor to the central nerves (radial nerve in starfish, sensory neuron in humans), both have some form of relay (spinal cord and the ring nerve thing), both have reflexes. Differences; humans have a brain which can override the reflex, humans have a spinal cord, humans can make conscious choices, starfish only exhibit simple reflexes.
Transport in plant roots was 1 mark, it was osmosis I believe.

There was 2 marks on cystic fibrosis mucus, I first defined osmosis and said it was sticky because the calcium/water was unable to leave the cell like normally they can, to enter the mucus? I think I said that the calcium is in the water, hence its osmosis, but cant remember or know if that is right.

Ecstacy and PTSD conclusion (1) Ecstacy, when used in conjunction to regular therapy, is more effective than therapy alone.
Scientists being sure of the conclusion (2) I know I mentioned other scientists would need to repeat, and explain the mechanism linking the ecstacy to better recovery.

Calculations: 0.0012%
9000 people with the specific gene?

how did you get 0.0012%?

Reply 6

what did everyone get for the serotonin question? i put C A E B D but then changed it to C A B E D

Reply 7

Deliciate

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Original post by tanishaevans

what did everyone get for the serotonin question? i put C A E B D but then changed it to C A B E D

Can't remember. Do you vaguely remember what the letters stand for?

Reply 8

username3167456

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Original post by tanishaevans

how did you get 0.0012%?

3 genes out of 250 000, so (3/250 000)
(3/250 000)*100 = 0.0012%

Reply 9

Original post by tanishaevans

what did everyone get for the serotonin question? i put C A E B D but then changed it to C A B E D

Can't remember the letter order but it was 1) serotonin goes back to first neutron 2 concentration of serotonin increases in gap 3) more serotonin on next neuron membrane 5) more impulses generated

Reply 10

Original post by samwesttt

3 genes out of 250 000, so (3/250 000)
(3/250 000)*100 = 0.0012%

I did that but kept it in standard form

Reply 11

Deliciate

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Original post by tanishaevans

what did everyone get for the serotonin question? i put C A E B D but then changed it to C A B E D

I don't remember putting C A B E D; C A E B D looks more familiar.

Reply 12

Original post by samwesttt

3 genes out of 250 000, so (3/250 000)
(3/250 000)*100 = 0.0012%

i could not figure out how to do it >_< i was trying to do something like this but doing 250000/3 instead, makes sense now. ugh.

Reply 13

For the question of faulty DNA , did you have to mention how protein is made? I just talked about the amino acid coding and the fact that it codes for protein and described the structure of DNA as the question said 'describe DNA and why a mutation would cause a faulty protein being made'

Reply 14

Original post by menna123

Can't remember the letter order but it was 1) serotonin goes back to first neutron 2 concentration of serotonin increases in gap 3) more serotonin on next neuron membrane 5) more impulses generated

ok, i'm pretty sure that's what i put. i was confused w/ the order of "concentration of serotonin increases" and "more serotonin on next neurone" if that's right then i'm sure CABED is the correct letter order! thanks

Reply 15

Deliciate

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Original post by menna123

For the question of faulty DNA , did you have to mention how protein is made? I just talked about the amino acid coding and the fact that it codes for protein and described the structure of DNA as the question said 'describe DNA and why a mutation would cause a faulty protein being made'

I assume that you have to describe how a protein is made via the mRNA and in the cytoplasm by ribosomes. However, the main idea is that you have to say that the faulty order of bases will code for the sequence of amino acids which therefore makes a faulty protein. You should be good if you described the mRNA process (although I doubt it has to be in too much depth). The examiners report highlighted how candidates fail to use the terms 'sequence' and 'amino acids' in their answers so they wanted to test our ability there.

Reply 16

Original post by menna123

For the question of faulty DNA , did you have to mention how protein is made? I just talked about the amino acid coding and the fact that it codes for protein and described the structure of DNA as the question said 'describe DNA and why a mutation would cause a faulty protein being made'

i didn't talk about the ribosome or mRNA or anything, i just wrote about the two strands being coiled together in double helix shape and being made up of nucleotides and how they're attached by the bases, thymine adenine cytosine guanine A-T C-G and if the order is changed the protein wont code for what it was supposed to code for or something. anyone know if this is right?

edit* also spoke about triplets coding for one amino acid and them being joined to make a protein but not where it happens or how

(edited 6 years ago)

Reply 17

I said something on these lines:
DNA is a double helix of paired bases which always pair up in the same way A-T C-G, the order of bases in DNA (tripled code) code for one amino acid. Amino acids are joined together to make proteins, each amino acid has a unique set of three bases and each protein requires a particular order/sequence of amino acids. The change of the base order means that a different amino acid is coded for and so therefore a different/faulty protein is made as different proteins have different sequences of amino acids.
I think that would be worth 2 marks lol

Reply 18