Qualification > Sciences
ALL CIE BIOLOGY DOUBTS HERE !!!
Amelia:
--- Quote from: Sue T on January 05, 2011, 08:07:07 am ---A2 : section B nov 2008 it says Describe and explain, using an example, the process of artificial selection.
ok so then in th m.s. 2 points wer like:
-background genes ;
-loss of hybrid vigour / increase in homozygosity / ref. inbreeding depression
does ny1 no wat these r?
+ if ny1 hs some notes on all ths speciation, artificial selection things pls do attach - my text book hs become useless :'(
--- End quote ---
- Hybrid vigour (heterosis/outerbreeding enhancement) describes the strength of different characteristics in hybrids; the possiblity of obtaining a genetically superior individual by combining the virtues of its parents.
Homozygosity: The state of possessing two identical forms of a particular gene, one inherited from each parent.For example, a girl who is homozygous for cystic fibrosis (CF) received the CF gene from both of her parents and therefore she has CF.
Interbreeding depression - is the reduced fitness in a population as a result of breeding of related individuals. It results in more recessive deliterious traits manifesting themselves. More homozygous deleterious genes the offspring may have, the more unfit the offspringproduced.
Check out these links.
Speciations - http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Speciation.html
http://www.dr-evans.com/advancedbiology/evolution.html
http://www.sparknotes.com/biology/evolution/naturalselection/section3.rhtml
Sue T:
thanks alot! :D
Amelia:
--- Quote from: Sue T on January 05, 2011, 04:25:03 pm ---thanks alot! :D
--- End quote ---
I dint realize I've quoted your question twice! :D
Welcome!
Sue T:
another question - a small one
(b) Explain the role of gibberellins in the germination of wheat or barley.
among all th points was :
13 gibberellin produced by embryo plant ;
14 passes to aleurone layer ;
15 switches on / activation, transcription enzyme genes / AW ;
16 storage proteins broken down to amino acids ;
17 stimulates synthesis / release of amylase ;
18 amylase diffuses / moves into endosperm ;
now points 15 16 17 - which enzyme is being transcripted? is it like a protease cuz in th nxt step they go like proteins to aminos? & then amylase is synthesised because of the aminos?
Amelia:
--- Quote from: Sue T on January 06, 2011, 07:49:22 am ---another question - a small one
(b) Explain the role of gibberellins in the germination of wheat or barley.
among all th points was :
13 gibberellin produced by embryo plant ;
14 passes to aleurone layer ;
15 switches on / activation, transcription enzyme genes / AW ;
16 storage proteins broken down to amino acids ;
17 stimulates synthesis / release of amylase ;
18 amylase diffuses / moves into endosperm ;
now points 15 16 17 - which enzyme is being transcripted? is it like a protease cuz in th nxt step they go like proteins to aminos? & then amylase is synthesised because of the aminos?
--- End quote ---
The outerlayers of endosperm contains proteins which is the source of amino acids for protien synthesis.
Germination is triggered by soaking the seed in water. After imbibing water the embryo secrets gibberellin which diffuses into the aleurone layer, stimulating synthesis of several enzymes including alpha amylase. These enzymes catalyse the breakdown of food reserve in the endosperm, and the products of digestion diffuse to the embryo, where they are used in growth.
Take a look at the images to understand better. :)
http://4e.plantphys.net/images/ch20/wt2002c_s.jpg
http://forums.mycotopia.net/attachments/testing-formating/30670d1154787401-seed-germination-lab-seedgerm.gif
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