GCSE OCR 21st Century Triple Science (CBP1-7) Thread

What the.... I wish I didn't see those diagrams. Now I'm confused :/


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Don't worry I've sorted it out
Mitosis:
1) dna separates and duplicates itself. It forms an 'x' shape with its 'twin dna strand'
2) the 'x's line up in the middle
3) the two arms get pulled to the opposite sides
4) at each side of the cell you have genetically identical material.
5) nucleus membrane forms around each of the two cells
6) they split
7) they have genetically identical chromosomes, 46 strands each

Meiosis:
1) DNA duplicates itself, forms an 'x'
2) DNA 'x' shapes with similar genes pair up. Some genes are swapped around (variation)
3) the pairs are pulled apart (one x from each pair goes to one side, one goes to the other)
4) this results in two cells
5) now in each of the two cells, the 'x' lines up in the middle
6) each arm of the 'x' is pulled apart, just like in Meitosis
7) now you get four individual cells
8) they each have 23 single chromosomes

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Ohh thanks, I get it now urgh Bio is so much content it's annoying.

DOONE! I've finished my bio spec notes thing! I've noticed so many words in the spec are ones you must include in exams. Going through it really helped

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Where do you find this spec

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http://www.ocr.org.uk/qualifications/gcse-twenty-first-century-science-suite-biology-a-j243-from-2012/
Under 'key documents' is the specification for biology and scroll down the the B456 section

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Please could someone explain how ecstasy affects the transmission of impulses across a synapse?

Please could someone explain how ecstasy affects the transmission of impulses across a synapse?

Woah, what table? What flame test? What topic is this? D8 XDDD

I'm sure you guys are all really busy with your own revision, but would any of you be able to explain why impulses in synapses only go one way?

Please could someone explain how ecstasy affects the transmission of impulses across a synapse?

Don't worry I've sorted it out
Mitosis:
1) dna separates and duplicates itself. It forms an 'x' shape with its 'twin dna strand'
2) the 'x's line up in the middle
3) the two arms get pulled to the opposite sides
4) at each side of the cell you have genetically identical material.
5) nucleus membrane forms around each of the two cells
6) they split
7) they have genetically identical chromosomes, 46 strands each

Meiosis:
1) DNA duplicates itself, forms an 'x'
2) DNA 'x' shapes with similar genes pair up. Some genes are swapped around (variation)
3) the pairs are pulled apart (one x from each pair goes to one side, one goes to the other)
4) this results in two cells
5) now in each of the two cells, the 'x' lines up in the middle
6) each arm of the 'x' is pulled apart, just like in Meitosis
7) now you get four individual cells
8) they each have 23 single chromosomes

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B4 Six Markers:


Comparing parts of plant/animal cell, what they do, how they help respiration.
Explaining how enzymes work + analysing/explaining data? How pH/temperature affects? Graphs?
Comparing aerobic and anerobic respiration and the advantages/disadvantages?
Comparing uses of fermentation. (Biogas/Bread/Alcohol). Maybe some explanation.
Explaining rate of photosynthesis, limiting factors, etc + analysing/explaining data.
Taking a transect/using a quadrat/light meter/ identification key.
The differences between diffusion/osmosis/active transport. Perhaps analysing/evaulating data? (I HOPE THIS ONE ISN'T USED! ><)
Comparing respiration between human cells/plant cells/bacteria cells.



B5 Six Markers:

Explaining how proteins are made by ribosomes.
Comparing Meiosis and Mitosis.
Comparing Adult Stem Cells and Embryonic Stem Cells + ethics?
Explaining how to clone using stem cells.
Explaining how to clone plants. (Cuttings, meristems, rooting powder, etc).
Explaining Phototropism and Auxins + analysing/explaining data?

B6 Six Markers:

Comparing CNS and PNS. Maybe just explaining either?
Explaining how the CNS coordinates a response with a given scenario (like, a bird sees a cat).
Explaining Synapses + why impulses can only go one way.
Explaining the reflex arc with a given scenario. (Sarah's leg still reacts when the doctor hits it with a hammer).
Explaining simple relflexes with different examples. (Sea anemones wave their tentacles when stimulated by pray's chemicals, molluscs close their shells, human eye contracting with increased light, etc, etc,).
Explaining Pavlov's dogs/conditioned reflexes.
Comparing brain development between child and adult + explain. Possibly explaining data. Maybe even comparing normal and feral children.
Different ways to study the brain + ethical issues.
Explaining how memory works + model.

(Updated version. The possible 6 markers in bold have already been asked in previous papers, HOWEVER, this doesn't mean they won't come up!!)

Ecstasy blocks the sites in the Brain's synapses where the neurone transmitter (serotonin) is removed. This means that the concentration of serotonin increases in each synapse and the frequency of the impulse too.

Why does the frequency increase also? Is this correct:
the serotonin concentration in the spynapse will increase as it cannot get absorbed by the post synaptic neuron therefore since there is an increase in serotonin concentration more molecules will be available to bind to the receptor molecules therefore increasing the frequency of nerve impulses??
or does ecstasy block all receptor molecules
im really cnfused!

In the spec it says that candidates don't need to know the intermediate stages of meiosis/mitosis
Spec: http://www.ocr.org.uk/Images/82526-specification.pdf (page 50)