EdExel Biology Unit 5 Watch
That eye question threw me as well because i'd been revising from the CGP books, which don't have anything about the eye. So i hadn't revised the eye and got completely thrown. Fortunately i had this faint recollection of rhodopsin turning into retinal and opsin when exposed to light, and the rods being involved in detecting light intensity. Is that right?
does changing shape count as stretching?
muscular walls (muscularis externa+media+interna) - to prevent arteries from bursting under high blood pressure
elastic fibres - which can stretch + recoil, to maintain blood pressure
You could include something on vasoconstriction/vasodilation aswell. but I can't remember where..
I thought that was easy :P
I just dissolved into tears when I got out of that exam, I hated it! And I have revised for hours and hours, been over every single past paper since 2001 and I do know my stuff -just felt like i was trapped in sinking sand when I opened it! goodbye uni
Snap! so did i...still cnt get over it..and the worst thing is...that i have 2 go over it all AGAIN cause of synoptic...its gona b such a killer realising all the mistakes i made...and all the stuff i didnt know
doesnt the question say that the disease develops due to a recessive allele. if 3/4 had the ressecive allele then would they have a chance of the disease developing?
recessive inherited from both parents: double recessive: rr
the question did not say that it is caused by homozygous resessive
And because the parents have already had a child with the disease you know that they must both be heterozygous. Rr x Rr gives RR, Rr, Rr, rr. So there's a 25 % chance of the next child developing the disease.
ahh this question pissed me off i made up some crap about the mule not having the same characteristics as donkeys and horses both physically and genetically so they cant have the same genus but nothing about goddamn interbreeding. edexcel expect us to memorize every detail of the whole specification and they just bring up random questions out of 1000 possibilities its just impossible to get every question completely right.
and for the question about the bonds i stupidly wrote covalent and ionic, since disulphide bonds are covalent it doesnt really count. otherwise the answer is ionic and hydrogen which are both weaker than the disulphide. in chemistry for those who are wondering hydrogen>dipole dipole>van der waals but these are all between polar molecules covalent bonds are stronger...