OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

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acdunn

Argggh, please help, I was revising epistasis, but I don't understand the difference between 'recessive epistasis' and 'genes working in a complementary fashion'

In the OCR (purple) biology textbook page 133 Q4 it asks if the whole 'agouti mice/white mice/black mice' thing is an example of recessive epistasis or complementary gene action or both???????????????

It depends.

If the recessive allele is for white, for example bb, and this masks the expression of the allele for black say BB wherever it occurs, this is an example of recessive epistatis, as the white allele is masking the expression of the black allele. If the mouse is Agouti, it needs a mixture of both white and black hairs I guess, and it needs to be able to make the enzyme for both, so for example:
Colourless->White->Agouti. If both alleles are needed for the agouti colouring and it does not say that one masks the expression of another, then this would be complementary epistasis as both of the alleles are needed to make agouti.

Not sure if this makes sense.

Reply 2101

Remarqable M

Module 1 +2 PAck :wink:

received it kindly from OP in this thread

http://www.thestudentroom.co.uk/showthread.php?&p=25715037#post25715037

credit to user: Waffles n Further Waffles

Biotechnology and gene tech questions F215.rtf1528.0KB

Biotechnology and gene tech answers F215 (1).rtf140.7KB

Cellular control answers F215.rtf225.7KB

Cellular control questions F215.rtf1235.1KB

Reply 2102

PJ991

Exam is next week. I have done some revision but have focused on earlier exams. Can I cover ~150 text book pages, which is probably about 70 spreads, in a week?

It's gonna be a challenge.

Reply 2103

Remarqable M

Ecosystems and Sustainability
:wink:

again credit to user: Waffles n Further

Ecosystems and sustainability questions F215 part 1.rtf1044.0KB

Ecosystems and sustainability questions F215 part 2.rtf733.4KB

Ecosystems and sustainability questions F215 part 3.rtf772.3KB

Ecosystems and sustainability answers F215.rtf60.5KB

Reply 2104

aiden1234

anyone able to give a quick overview of homeobox genes? are they just genes that code for transcription factors, and these control the early development of organisms, such as coding for segmentation etc. etc.?

Reply 2105

mikey_g

PJ991

Exam is next week. I have done some revision but have focused on earlier exams. Can I cover ~150 text book pages, which is probably about 70 spreads, in a week?

It's gonna be a challenge.

it's very possible! but not easy

Reply 2106

PJ991

mikey_g

it's very possible! but not easy

I look at it this way:

Some areas I'm good on so I don't need to spend as much time on them. For the ones I need to do, I can read and do notes in 20 minutes or so per spread.

If I get it down to 15 minutes per spread, 6 hours a day, that 24 per day which will be it all done in 3 days, leaving a bit of time for past papers etc.

And I only need a B so have a bit less pressure than otherwise if I needed an A in it.

Reply 2107

Falcon91

aiden1234

Homeotic genes: Master control genes for development. Proteins code for a body plan which is set by the homeotic genes.
Homeotic genes are found as maternal effect genes - they determine the polarity of the embryo/body and then the segmentation genes - determine the polarity of each segment.

The homeotic genes are found in clusters called homeobox clusters, these appear to be common in many animals are so fundamental to development of bodies.

The homeobox clusters code for proteins that act as transcription factors binding furthur along DNA and act as transcription factors activating or repressing certain genes and so changing the production of proteins and so the body plan.

Vitamin A acts as a mutagen, can activate homeotic genes and thus causes mutation as it will activate/repress them in a different order to develop the body. (Not sure if this is needed by vitamin A seems to come up ALOT throughout our syllabus).

Reply 2108

Rill

Remarqable M

Module 1 +2 PAck :wink:

received it kindly from OP in this thread

http://www.thestudentroom.co.uk/showthread.php?&p=25715037#post25715037

credit to user: Waffles n Further Waffles

The questions in those papers are.... really hard is anyone else finding these difficult?

Reply 2109

dontkillhannah

hi everyone, I was just wondering if any of you knew whether or not we'll be tested on F214 as part of the synopticy bit of F215? Or will it just be AS modules?

Reply 2110

Falcon91

dontkillhannah

hi everyone, I was just wondering if any of you knew whether or not we'll be tested on F214 as part of the synopticy bit of F215? Or will it just be AS modules?

Its likely to include some of F214, synapses, photosynthesis and respiration are the most likely to come up i guess. Maybe endo and ecotherms too depending if they ask about behaviour.

Reply 2111

nbailey8

I hate how the specimin paper is nothing like the real one will be like.
Well, it wasn't for F214 at least..

Reply 2112

dontkillhannah

Falcon91

Its likely to include some of F214, synapses, photosynthesis and respiration are the most likely to come up i guess. Maybe endo and ecotherms too depending if they ask about behaviour.

Ah, thanka (: I'm so so worried about this exam :frown:

I hope they don't ask for too much detail in the synoptic

Reply 2113

Falcon91

dontkillhannah

Ah, thanka (: I'm so so worried about this exam :frown:

I hope they don't ask for too much detail in the synoptic

Me too, im so scared as well lol. Hopefully i just get at least a B. Its all i need for this :biggrin:

And yeah, hate how its not like the spec as i usually get good marks in the spec! and a mock my college put together. Blast it!

Reply 2114

Ohhai

I need chucks revision cards... :frown:

Reply 2115

Ohhai

PJ991

Exam is next week. I have done some revision but have focused on earlier exams. Can I cover ~150 text book pages, which is probably about 70 spreads, in a week?

It's gonna be a challenge.

Same position as you...planning to do about 4 hours a day...you should be okay.

Reply 2116

mikey_g

PJ991

good luck! the first time going through the book (learning) took 2 weeks, but ive just gone through it with a topic a day (so 4 days total), that's with some generous breaks though haha

Reply 2117

MasterJomi

I'm kind of in the same position, but I've got 4 other exams next week which I'm also in the same position... Going to be 'No-life'ing the next week. I've looked at some past papers and tried he odd question and I get like 2 out of % for most of them... Just not using enough detail or just answer the question wrongly.

Reply 2118

s_a_r_a

Ohhai

I need chucks revision cards... :frown:

^^^^^ me tooooooo :o:

Reply 2119

Falcon91

Hmm after doing those questions. I find some of the information a bit strange, such as genetic screening and the part about fireflies, as well as the parts about cross pollination (really did we get taught that somewhen?) lol. But i got the majority of the biotech ones fairly well, just need to watch for those specific words.