Author Topic: Edexcel BIOLOGY Doubts!!!!  (Read 133127 times)

Offline Weaam

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #240 on: December 04, 2010, 02:54:36 pm »
The graph below shows changes in the blood pressure in the aorta and the left ventricle during two complete cardiac cycles.
(a) On the graph, draw an arrow to show when the left atrioventricular (mitral) valve closes.
(b) Use the information in the graph to calculate the heart rate. Show your working.

Don't know how to calculate the heart rate (b) ,  anyone  explain
Markscheme says: (b) 60 รท 1.0 ; [accept equivalent calculations] = 60 beats per minute ; [accept range 60 to 64], but how does 60 beats come only pressure and time in seconds is given? Thanx in advance  :)
I had this question in an exam xDD
anyways to calculate the heart rate:
1 beat -----> 0.96sec (from graph, since a full beat finishes then)
X beats ----> 60 seconds

Then cross multiply it to get the answer
X = 60/0.96 = 62.5
See the picture if u still dont get it.
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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #241 on: December 04, 2010, 03:35:26 pm »
I had this question in an exam xDD
anyways to calculate the heart rate:
1 beat -----> 0.96sec (from graph, since a full beat finishes then)
X beats ----> 60 seconds

Then cross multiply it to get the answer
X = 60/0.96 = 62.5
See the picture if u still dont get it.

+rep ;)

Offline Weaam

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #242 on: December 04, 2010, 03:41:48 pm »
- The man who smiles when things go wrong has thought of someone to blame it on. - Robert Bloch.
-I saw weird stuff in that place last night. Weird, strange, sick, twisted, eerie, godless, evil stuff... and I went in. - Homer
+ Rep me if i have been of any assistance to you ;D

Offline -Cornea

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #243 on: December 04, 2010, 04:50:10 pm »
how can i explain ionization:D i know stupid question though=p
Laughter is the shock absorber that eases the blow of life ! =)

Offline Weaam

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #244 on: December 04, 2010, 05:10:43 pm »
how can i explain ionization:D i know stupid question though=p
Ionization is chemistry ?
- The man who smiles when things go wrong has thought of someone to blame it on. - Robert Bloch.
-I saw weird stuff in that place last night. Weird, strange, sick, twisted, eerie, godless, evil stuff... and I went in. - Homer
+ Rep me if i have been of any assistance to you ;D

Offline -Cornea

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #245 on: December 04, 2010, 05:35:13 pm »
nah about the  water part :D
Laughter is the shock absorber that eases the blow of life ! =)

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #246 on: December 04, 2010, 06:39:01 pm »
how can i explain ionization:D i know stupid question though=p

Ionization is the physical process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. ;)

But did you mean polarization? or it is ionization? :-\
« Last Edit: December 04, 2010, 07:03:47 pm by Hamlet »

Offline xstrawberryswingx

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #247 on: December 08, 2010, 02:15:55 pm »
June 2010 Unit 1 Question 3 a ii)

Offline xstrawberryswingx

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #248 on: December 08, 2010, 02:17:13 pm »
The mark scheme just says "Reference to .. Reference to.." but that doesnt help =/

Offline MKh

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #249 on: December 08, 2010, 08:08:43 pm »
Iz any1 preparing 4 edexcel A2 unit 6B?...cud any1 suggest me hw i shud prepare 4 it?... ??? Thanks in advance

Offline MKh

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #250 on: December 08, 2010, 08:27:57 pm »
hey guyz...i hav a doubt in edexcel biology unit 6B...cud any1 help me wid d statistical tests part?
i know dat v r not expected 2 know d  formulae or fine details of each test n i even know dat v must only concentrate on selecting d correct type of test and demonstrate our understanding on how 2 interpret d results-this has been stated in the revison guide.
cud any1 plz temme how 2 select d correct type of test and demonstrate our understanding on how 2 interpret d results???

Offline Amii

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #251 on: December 08, 2010, 09:23:00 pm »
June 2010 Unit 1 Question 3 a ii)

Molecule A --->Phospolipid

Phospolipids consists of a polar phosphate group which carries a negative charge and is soluble in water - hydrophilic(water-loving).The fatty acid chains(lipid tails) of a phospolipid are neutral and insoluble in water- hydrophobic(water-hating).The hydrophobic molecules are attracted to each other. In water, phospholipids form double layer with the hydrophilic heads pointing into the water and the hydrophobic tails away from water in the centre. The attraction between the hydrophobic tails in the centre and between the hydrophilic heads and the surrounding water makes membranes very stable.

Hope it helps
Take care  :D

« Last Edit: December 08, 2010, 09:26:19 pm by Sherlock Holmes »

By my sweeett nephew ;D

Offline Deadly_king

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #252 on: December 09, 2010, 11:33:39 am »
hey guyz...i hav a doubt in edexcel biology unit 6B...cud any1 help me wid d statistical tests part?
i know dat v r not expected 2 know d  formulae or fine details of each test n i even know dat v must only concentrate on selecting d correct type of test and demonstrate our understanding on how 2 interpret d results-this has been stated in the revison guide.
cud any1 plz temme how 2 select d correct type of test and demonstrate our understanding on how 2 interpret d results???


How to choose the right statistical test?


If you've been given measurements, i.e specific values of a certain thing, you should use :

(i) Standard deviation and standard error when you're looking for variability between the measurements.

(ii) T-test when you're looking for the difference between means.

If you've been given frequencies and you're asked to find the number of individuals in a particular category, then the chi-squared test is used.

Offline moon

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #253 on: December 09, 2010, 12:03:49 pm »
Is the chi-squared test in the syllabus???

Offline Deadly_king

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Re: Edexcel BIOLOGY Doubts!!!!
« Reply #254 on: December 09, 2010, 12:09:26 pm »
Is the chi-squared test in the syllabus???

Hmm..............I don't know about EDEXCEL but it is for CIE. ;)