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Upcoming Edexcel AS Biology: Unit 2 exam on 26 May 2011

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what did u guys write for the last question when they ask you which data is more reliable the one collected from cold water or hot water?

I said the cold water one, as the error range was smaller, only ±0.6 instead of ±1.4 (I think) for the hot water, so it was more reliable.

Reply 101

heyadinzi

i didnt understand what the golgi question was asking and what did u put for the last question ??

Reply 102

bertiejess

Original post by CJRyan

I put 11,000 because it was number of genes 'not switched off,' which I thought meant the number of genes are switched on :s-smilie:

If 23,000 genes were 'switched on' it would be specialised, because stem cells need the genes activated, switched on, to become specialised

That is so annoying - Edexcel :angry:

Reply 103

heyadinzi

what did you guys write for the golgi one! and i didnt get the last question will someone tell me what they rote

Reply 104

godknows

Original post by Charlesworth

I said the cold water one, as the error range was smaller, only ±0.6 instead of ±1.4 (I think) for the hot water, so it was more reliable.

Original post by heyadinzi

i didnt understand what the golgi question was asking and what did u put for the last question ??

i wrote the same.. tht cold water had smaller range so it is more reliable :biggrin:

what about the question above it asking for the overlapping of range :s-smilie:

i jus found the range of both of them n showed how they overlap :/

Reply 105

heyadinzi

yeh so did i !! what other questions came up that were hard.. the telophase one was annoying !! what did u do for the crossing over one

Reply 106

CJRyan

Original post by heyadinzi

what did you guys write for the golgi one! and i didnt get the last question will someone tell me what they rote

For the appearance of the Golgi i said there would be several cisternae, curving from convex to concave, and you would see vesicles forming around it.

For the functions of the Golgi and rER in the cell I just blabbed about protein synthesis :colondollar:

Reply 107

godknows

Original post by heyadinzi

yeh so did i !! what other questions came up that were hard.. the telophase one was annoying !! what did u do for the crossing over one

for the first one shaded three of the strands in :s-smilie:

n for the second one shaded one of them

Reply 108

CJRyan

Original post by godknowsprerna

i wrote the same.. tht cold water had smaller range so it is more reliable :biggrin:

what about the question above it asking for the overlapping of range :s-smilie:

i just found the range of both of them n showed how they overlap :/

For the overlapping question I showed the range of hot and cold water and then said where the overlapped

Reply 109

godknows

Original post by heyadinzi

yeh so did i !! what other questions came up that were hard.. the telophase one was annoying !! what did u do for the crossing over one

what did u guys write about the endemism questions .. i wrote its in Area D cauz tht was the only area with a unique species o.O to other areas

Reply 110

CJRyan

Original post by godknowsprerna

what did u guys write about the endemism questions .. i wrote its in Area D cauz tht was the only area with a unique species o.O to other areas

Yeah I chose D as well, it had the flag shaped shape; I don't know why but that question reminded of some sort of IQ quiz trying to spot all the shapes :tongue:

Reply 111

godknows

Original post by CJRyan

Yeah I chose D as well, it had the flag shaped shape; I don't know why but that question reminded of some sort of IQ quiz trying to spot all the shapes :tongue:

LOOOOOL ahaha I THOUGHT EXACTLY THE SAME :/ N CRACKED UP :L n then one of the invigilators gave me evils ¬_¬ LOL

Reply 112

heyadinzi

yeh there was also the antimicrobial one and the really weird other experiment one !! what did u right for that and did u get confused in the taxanomic grouping ones when it tells u about archae what did ou write

Reply 113

Charlesworth

Original post by heyadinzi

For the taxonomic groupings, I said eukarota was C and archaea was B :s-smilie:

The antimicrobial one was okay about from the question asking how to put the bacteria in the petri disc. Honestly didn't have a clue.

For the next one about why they taped the disc like that, I said to prevent anaerobic respiration, as many harmful bacteria could be grown in anaerobic conditions. For the 37C question, I said so it won't grow bacteria that prefer 37C, the same temperature as humans, so they are likely to be harmful to humans.

Reply 114

heyadinzi

i also hated he taxonomic grouping one !! what did u put forthe rer and golgi!! nad some weird question about nitrogen!! AND THE crossing over eurgggh

Reply 115

Alakamind

Original post by CJRyan

I put 11,000 because it was number of genes 'not switched off,' which I thought meant the number of genes are switched on :s-smilie:

If 23,000 genes were 'switched on' it would be specialised, because stem cells need the genes activated, switched on, to become specialised

No, all the cells start off as totipotent, it says how many genes are able to be activated in the cell. So 2300 was generally correct, as the active genes mrna can be transribed to form 2300 different proteins thus allowing the most cell types as each protein is unique.

(edited 12 years ago)

Reply 116

britchick

Original post by CJRyan

I put 11,000 because it was number of genes 'not switched off,' which I thought meant the number of genes are switched on :s-smilie:

If 23,000 genes were 'switched on' it would be specialised, because stem cells need the genes activated, switched on, to become specialised

The only downside of coming on Student Room is when you get depressed from all the questions you thought you got right, count towards the ones you got wrong...

SO disappointed. I was really confident for the exam, then hardly anything to do with biology came up?!

With the 6 mark question on Golgi/rER i could answer it yay :biggrin:

i usually do bullet points, but someone said you're marked possibly on structure and grammar... so i wrote it as a continuous long answer (still did it in 6 or 7 sentences though to be able to read it better), but all the steps were chronological. Is that still okay?

(edited 12 years ago)

Reply 117

britchick

Original post by Charlesworth

It was okay. The question about gene locus, my mind went blank. Also, got confused with species richness and species diversity so got ticked the wrong box.

Also the question about which cell was totipotent because of the number of cells 'not switched off,' was the answer the one with 23000 genes or 11000 genes?

And the 5 mark question about zoos and breeding programs, I just babbled on and on.

Think overall thought it went okay, hope for a high B/low A :smile:

I talked about how the gene locus was the "address" of the gene/allele, its what our teacher had taught us XD thing is, questions like that weren't necessarily on the specification, you just sorta needed to know what they were as background information. Which is difficult because it's one of those things where you know what they are, but have no idea how to explain it.

I answered 23,000 because:
above the question the information said humans can be made up of a possible 23,000 genes. If a cell had all these 23,000 genes, then surely it means its cell coded for all proteins? Which means it can be used to perform any function i.e. is totipotent?

Eurgh the zoos question :s-smilie:

I answered:
- keeps them from dangerous conditions they faced in the wild (temperature change/lack of food resources/predators/hunting)
- they can keep stud books to record which organisms they have mated with from other zoos
- this increases the number of rare organisms alive and increases the gene pool; allows for more genetic diversity
- re-introductory programmes make sure that when the dangerous condition from their habitat has been removed, they are able to be re-introduced to the wild and produce offspring successfully to enhance their numbers

I just spent SOO long studying for this exam, literally about 50 hours, and felt like all of that had gone to waste because it was all about data/tables/graphs.

I hated the question about breeds P and Q dogs!!!

Reply 118

snow leopard

Original post by cjryan

i put 11,000 because it was number of genes 'not switched off,' which i thought meant the number of genes are switched on :s if 23,000 genes were 'switched on' it would be specialised, because stem cells need the genes activated, switched on, to become specialised

people - this guy is wrong.

Totipotent is when all the genes are switched on,

Mrna is only transcribed from switched on genes under the correct simulus.

They must all be switched on for the totipotent cell to differentiate into any cell, ask any good bio teacher.

Reply 119

britchick

Original post by godknowsprerna

and i think it was 23000 genes because all the genes have to be available for the cell to be totipotent

and omg i didnt have much to write for the golgi body question even though i knew the basic ideas but still got confused :frown:

n made like random bullet points...

i think the grade boundaries would be really high :/ because the paper was fairly easy [ i didnt like it though :frown:

all the hard stuff i spent ages revising for didnt cum up :angry:

lol ]

I said 23,000 for that reason too, so it could be able to code for all proteins and to carry out all functions etc :smile:

For the Golgi Apparatus question:
- at least 3 convex sacs ranging from smallest to largest
- the largest sac is the sac facing the ER i.e. the smallest sac is where functions are last carried out and is closest to the membrane
- the smallest sac is more condense with enzymes, which might be visible with a stain
- i drew a labelled diagram in case my explanation didnt make sense XD

For the Golgi apparatus/rER question:
- the transcripted RNA comes through the nuclear pores and attaches to the ribosomes (proteins) on the rER's surface
- the protein and genetic information travel through the rER, taking its 3D-like structure along the way
- vesicles pinch off the ends of the rER containing the protein and genetic information
- vesicles travel through the cytoplasm to the ends of the G.A's sacs, where they fuse into
- enzymes in the G.A modify the protein along its journey
- this includes the idea that if certain proteins need to be a certain direction e.g. receptors, the protein is turned in a certin way so it can be facing the rigth direction
- vesicles pinch off the ends of the G.A and travel to fuse with the cell membrane so it can carry out either intercellular/extracellular functions