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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

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Original post by master y
One of them has been answered now... but what would you guys write on energy trasnfers.. especially out of spec stuff? Thanks :smile:


Hi, you may find this essay useful to look at. Again, it would score 25/25
image.jpg556.5KB
Original post by nathaan5
anyone got a 3/4 markscheme answer of

1. what is transcription?

and

2 what is translation?

thanks :biggrin:


Transcription is the process where a pre-mRNa is formed from the template strand of a DNA which is a gene which codes for a protein. DNA helicase breaks the hydrogen bonds in the dna and then RNA polymerase joines the complementary nucleotides together to form a single RNA strand. This moves out of the nuclear pore into the nucleus. It is then spliced so that the introns are removed and the exons remain.

Can someone tell me if the wording of "formed from the template strand of a DNA which is a gene which codes for a protein" is correct... for example it wouldnt be "DNA codes for a gene which codes for a protein"....
Reply 3222
Avatar for bad8oy
bad8oy
14
Original post by peebs123
Why is the ADA gene inserted into T cells?


SCID is because of faulty ADA gene that codes for a defect enzyme. Normal ADA gene codes for enzyme that destroys toxins that otherwise kill white blood cells. If the ADA is injected into Tcells the T cells can produce the enzyme that destroys the toxins


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Original post by peebs123
Why is the ADA gene inserted into T cells?


Because T-cells develop into b-cells and hence antibodies
Reply 3224
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YWArtist
Original post by bad8oy
SCID is because of faulty ADA gene that codes for a defect enzyme. Normal ADA gene codes for enzyme that destroys toxins that otherwise kill white blood cells. If the ADA is injected into Tcells the T cells can produce the enzyme that destroys the toxins


Posted from TSR Mobile


Don't t-cells activate b-cells which divide into plasma cells, which have antibodies that bind to and neutralise toxins produced by pathogens..
Reply 3225
Avatar for igloo1
igloo1
DOES ANYONE HAVE ANY GOOD VIDEO RESOURCES, for especially coordination and nerves chapter?
is this right?

In an unsuitable environment, an organism will decrease it's rate of movement and it's direction will change more rapidly
Original post by peebs123
Could someone clarify.... Is kinesis and increase in random movements? Does that mean when they are in an unpleasnt environment they move more and rapidly change direction to find a more pleasant environment? thanks


Kinesis is rapid movement in different directions caused by an unpleasant stimulus that allows the organism to reach more suitable conditions... An example of this might be woodworms or maggots, as they live in dark conditions eg under a rock, so light would be the unpleasant stimulus that causes it to move around randomly (kinesis) until it reaches darker conditions
Hope that helped :smile:
Original post by cheesypuff
is this right?

In an unsuitable environment, an organism will decrease it's rate of movement and it's direction will change more rapidly

No
In unsuitable environments, its direction will change less frequently. An organism will move more rapidly. :smile:

An example of kinesis as stated above.
(edited 10 years ago)
Original post by LegendX
.

Thank you :smile: You are a legend
Original post by frogs r everywhere
No
In unsuitable environments, its direction will change less frequently. An organism will move more rapidly. :smile:

An example of kinesis as stated above.


can u explain this please? thank u .
Reply 3231
Avatar for Aimee18
Aimee18
What did everyone get at AS and Unit 4? (just out of curiosity)
Original post by frogs r everywhere
If they are in unpleasant environments, they do not rapidly change direction. They change direction less frequently.

If they are in pleasant environments, they then rapidly change direction which causes the organism to remain in the same place.


waaaa? that's confusing...
Original post by cheesypuff
is this right?

In an unsuitable environment, an organism will decrease it's rate of movement and it's direction will change more rapidly


An organism will change direction more rapidly to find suitable conditions (kinesis), but the rate of movement depends on the intensity of the stimulus, although usually I think its an increase in movement, because it means the suitable conditions are reached faster.
Reply 3234
Avatar for peebs123
peebs123
Original post by frogs r everywhere
If they are in unpleasant environments, they do not rapidly change direction. They change direction less frequently.

If they are in pleasant environments, they then rapidly change direction which causes the organism to remain in the same place.


The nelson thornes book says, 'the more unpleasant the stimulus the more rapidly it moves and the more rapidly it changes direction. A kinesis therefore results in an increase in random movements'. Now i'm confused....
Original post by Aimee18
What did everyone get at AS and Unit 4? (just out of curiosity)


Isn't Aimee a french name? :tongue: Both A's. (lets pray for Unit 5)
Retook unit 4 for an A*.
(edited 10 years ago)
Original post by peebs123
The nelson thornes book says, 'the more unpleasant the stimulus the more rapidly it moves and the more rapidly it changes direction. A kinesis therefore results in an increase in random movements'. Now i'm confused....


The more unpleasant the conditions = the faster/ increased rate of movement
Reply 3237
Avatar for Anjna
Anjna
9
Original post by peebs123
The nelson thornes book says, 'the more unpleasant the stimulus the more rapidly it moves and the more rapidly it changes direction. A kinesis therefore results in an increase in random movements'. Now i'm confused....


yeah I thought if it is moving more rapidly and randomly sure it changes direction frequently
Original post by Anjna
yeah I thought if it is moving more rapidly and randomly sure it changes direction frequently


Original post by gingerandice
waaaa? that's confusing...



Original post by peebs123
The nelson thornes book says, 'the more unpleasant the stimulus the more rapidly it moves and the more rapidly it changes direction. A kinesis therefore results in an increase in random movements'. Now i'm confused....



Original post by master y
can u explain this please? thank u .


Hello

No the book has it wrong (in my opinion)

when in favourable conditions a kinesis would be that the organism slows down movement and changes direction more.
When is unfavourable conditions, the organism will speed up and change direction LESS

http://www.thestudentroom.co.uk/attachment.php?attachmentid=101092&d=1305044171

The top image shows an organism in unfavourable conditions
The bottom image shows an organism in favourable conditions
(edited 10 years ago)
Original post by EllieSp
well hello there,

Severe combined immuno deficiency is caused by a defect in the gene for the enzyme that destroys toxins of white blood cells. It is inherited.

Sufferers do not show cell mediated immune response and do not produce antibodies

These are those people that have to live in bubbles that are sterile (isolation tents) and they inject the enzyme.

You can treat it by isolating the normal gene using restriction enzymes and then inserting it into the T cells of the patient using retro viruses that inject DNA into the cells
Then put the transformed T cells back into the person :colone:


OMG YOU FOUND ME :borat:

Thanks pal :cool:

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