Edexcel GCE Biology Unit 4 6BI04 June 2013

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That was well weird, NO DATA ANALYSIS :O

Tiny little bit on global warming, no tree rings, peat bog etc

No succession as well omg

Got a feeling a made daft mistakes though :/

I put Cystine instead of Cytosine lawl. :|

Omg! I know no data!! That was a god send though...!

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Reply 521

SKK94

Original post by blue21

It was about the enzyme that was made from the virus and how it caused lysis to the cell membrane I think, it was quite confusing :s-smilie:

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Was it how the enzyme broke down the cell membrane?
I said, the enzyme is specific, and acts on cholesterol molecules in the membrane. I said that the cholesterol gives rigidity to the membrane, and when they are broken down by the enzyme, the membrane would rupture easily. Dunno if that's right :frown:

(edited 10 years ago)

Reply 522

blue21

Original post by Alia223

What did you write for the last question about changes in phenotype being too slow? I spoke about allele frequency and evolution =/

I thunk it was about the selection pressures being the same for both as they both occupy similiar niches etc...

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Reply 523

blue21

Original post by SKK94

That sounds like a pretty good answer, it was just suggest so I'm hoping if we talked about any part of the cell membrane we will get the mark, I started rambling on about the phospholipid bi layer!

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Reply 524

Lgambo

Original post by Ziggy_72

What about why measure the KJ over a year and not just the mass on one day for the NPP? I think I rambled on a bit there...

I BS that one. Put something about it takes a mean for the year as the energy available changes with seasons.
What did people put for the investigation to see what affect light had on the organism?

Reply 525

Lgambo

Oh and why can't virus survive a cut in the skin?

Reply 526

C94

Original post by Lgambo

Oh and why can't virus survive a cut in the skin?

I put about skin being impenetrable, and that the skin was made of Keratin.
It formed a tough barrier.

No idea if it is right though.

(edited 10 years ago)

Reply 527

SKK94

Original post by C94

I put about skin being impenetrable, and that the skin was made of skin.
It formed a tough barrier.

No idea if it is right though.

I said that too.
I also mentioned that maybe the pH of the skin causes the protein coat to deform, hence the virus becomes inactive?

Reply 528

C94

For the question regarding enzymes "S" and "T" or something. And they asked what their roles/function was....

For that I was saying that these were the enzymes : Integrase and Reverse transcriptase. I was talking about their roles, how Reverse transcriptase reverses transcription, and changes Viral RNA into Viral DNA, and how integrase integrates the Viral DNA in the host's cell.

Is this what we were supposed to do, or have I wrote BS?

Reply 529

SKK94

Original post by blue21

Yeah, they might allow for a range of answers, as long they make sense? :smile:

Reply 530

Taylor Swift

Original post by Lgambo

Oh and why can't virus survive a cut in the skin?

Inflammation

Reply 531

C94

Original post by SKK94

I said that too.
I also mentioned that maybe the pH of the skin causes the protein coat to deform, hence the virus becomes inactive?

Yeah, Good answer.

Reply 532

C94

Original post by Taylor Swift

Inflammation

Surely it has to get past the skin for any inflammation to occur ?

Reply 533

Taylor Swift

Grade boundaries on this paper??? I think it was WAY harder than others ...
I think I did really badly -.- (silly mistakes), need to really do well in unit 5! LOL

Reply 534

Taylor Swift

Original post by C94

Surely it has to get past the skin for any inflammation to occur ?

The first part was the skin has keratin protein which is hard, and this is seen as a physical barrier.

The second part of why it can't enter cells was inflmmation.

Reply 535

Lgambo

Original post by C94

Surely it has to get past the skin for any inflammation to occur ?

There were two questions,
Something like- why does the skin act as a barrier?
And- if a virus was to get into a cut, why wouldn't the body be infected?

Reply 536

C94

Original post by Taylor Swift

The first part was the skin has keratin protein which is hard, and this is seen as a physical barrier.

The second part of why it can't enter cells was inflmmation.

Yes that part would be correct

Reply 537

Taylor Swift

Original post by Lgambo

There were two questions,
Something like- why does the skin act as a barrier?
And- if a virus was to get into a cut, why wouldn't the body be infected?

It was keratin/protein ... Hard skin - Physical barrier
This was a question I saw from a past paper before!

Reply 538

vsmahal

Original post by Taylor Swift

It was keratin/protein ... Hard skin - Physical barrier
This was a question I saw from a past paper before!

I also put that the skin flora would prevent the colonization of bacteria and viruses.

Reply 539

Qwob

Original post by SKK94

I said that too.
I also mentioned that maybe the pH of the skin causes the protein coat to deform, hence the virus becomes inactive?

The skin acts as a physical barrier to the inside of the body, and skin flora (healthy bacteria on the skin) take up any space that otherwise pathogens would and the skin flora outcompete them.

Also the common cold virus won't infect any cells inside the blood stream because 1) it binds to a specific protein receptor in cells in the nose - these receptors might not be present in the blood stream or surrounding tissues so the virus can't infect any cells, and 2) any macrophages present will recognise the virus particles as foreign and ingest them through phagocytosis.

Honestly, I thought that was the easiest Biology 4 paper I've done out of the past papers. Definitely easier than January also. In recent years the grade boundaries have been highest of 67 for A*, but I can see it being 69-71 for an A* for this paper.

I probably dropped 5 marks on virus question, as I was confused about S, T and U, but hopefully I picked up 1 or 2 marks each on these questions. On the other questions I probably dropped the odd 1 or 2 marks, I'm expecting 75+ on raw marks.

Several of the questions seemed to be literally copied from other papers, e.g. the 'how cellulose is produced from the Calvin Cycle' question - I was revising that exact question the evening beforehand in a past paper. The question about reproductive isolation due to the behavioral differences of the chiffchaffs and worblers and their different mating songs - that was another question I've seen before.

I was also suprised at the fact they missed out a lot of key topics. Photosynthesis wasn't covered in too much detail, there was nothing on succession if I remember correctly, or entomology, I can't remember that either. Couldn't believe the fact there was no 3-4 mark data analysis questions as well!

Edit: Negging me? Because I found it easy? I'm allowed to find it easy, I wasn't being cocky or arrogant about it though! This was one of the easier papers in my opinion, sorry about that.