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Author Topic: Biolgy paper 1 help!  (Read 29121 times)

Offline unknown

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Re: Biolgy paper 1 help!
« Reply #195 on: June 07, 2009, 09:18:22 am »
Quote from: madee on June 07, 2009, 09:16:42 am
Quote from: unknown on June 07, 2009, 08:42:04 am
Quote from: kam on June 06, 2009, 12:14:11 pm
can someone explain the o2 in blood
i dont get tht either
hey it was abt to identify x n y remeber
x=lungs n y=blood cells
nw do u get it
it was body cells not blood cells
yeah body cells srry
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Offline 12345abc

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Re: Biolgy paper 1 help!
« Reply #196 on: June 07, 2009, 09:47:46 am »
plz explain this: if a sperm can survive for 3 days and an egg for 2,and if ovulation occurs anytime from day 13 to 15,why is the fertile period 7 days???
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Offline thukon

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Re: Biolgy paper 1 help!
« Reply #197 on: June 07, 2009, 09:57:09 am »
If the sperm is injected into the vagina 3 days before ovulation, the egg could get fertilized after 3 days. So take that date as the 10th.
Now if ovulation occurs on the 15th, the ovum survives for 2 days, thats till the 17th, so the egg could get fertilized.
So the 10th to the 17th. Thats 7 days.
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Offline 12345abc

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Re: Biolgy paper 1 help!
« Reply #198 on: June 07, 2009, 10:05:27 am »
oh ok...thanx a ton!!!!!
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Offline IGCSE hater!

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Re: Biolgy paper 1 help!
« Reply #199 on: June 07, 2009, 10:35:13 am »
can someone please help me with the menstrual cycle?
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Offline goin4dakill

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Re: Biolgy paper 1 help!
« Reply #200 on: June 07, 2009, 10:43:00 am »
Quote from: IGCSE hater! on June 07, 2009, 10:35:13 am
can someone please help me with the menstrual cycle?

Not tooo compicated..

0-4 days- lining breaks down (the bleeding)
4-13 days- uterus lining is built up again
13-28- uterus lining is maintained-awaiting embeddment of zygote

The days are different for everyone- but thats an approximate count.

Now, the hormones.
Oestogen- is to encourage the repair of the uterus lining
progesterone- maintains the lining

FSH and LH (dont know if u have to know it- but oh well)
Follicle Stimuating hormone + luteinizing hormone- to make the ovum

Hope it Helped!
oh and ovulation (when the little egg is realeased-) happens about the 13th day- when the uterus lining is built up
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Offline IGCSE hater!

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Re: Biolgy paper 1 help!
« Reply #201 on: June 07, 2009, 11:01:27 am »
hey Thanks!!! :D
it did help...u gave me the idea of it!
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Offline shafiq_92libra

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Re: Biolgy paper 1 help!
« Reply #202 on: June 07, 2009, 11:15:19 am »
oh and estrogen brings about ovulation
but during ovulation both estro and progesterone are low
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Manifest Destiny

Offline 12345abc

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Re: Biolgy paper 1 help!
« Reply #203 on: June 07, 2009, 11:18:30 am »
why is progesterone used in the pill?
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Offline Kim

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Re: Biolgy paper 1 help!
« Reply #204 on: June 07, 2009, 11:23:06 am »
Quote from: 12345abc on June 07, 2009, 11:18:30 am
why is progesterone used in the pill?
because the progestrone tricks the boidy into thinking that fertilisation has taken place so no oestrogen is produced so no fertilisation is produced
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After all is said and done, more is said than done.

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Re: Biolgy paper 1 help!
« Reply #205 on: June 07, 2009, 02:22:53 pm »
visit this site for menstrual cycle

http://msnbcmedia.msn.com/i/msnbc/Components/Interactives/Health/WomensHealth/zFlashAssets/menstrual_cycle_dw2[1].swf

it has everything + animation

hope u like it
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Offline 12345abc

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Re: Biolgy paper 1 help!
« Reply #206 on: June 07, 2009, 03:03:26 pm »
is the brain not involved in reflex actions???
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Offline shafiq_92libra

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Re: Biolgy paper 1 help!
« Reply #207 on: June 07, 2009, 03:52:39 pm »
no its not
its informed later
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Manifest Destiny

Offline AS girl

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Re: Biolgy paper 1 help!
« Reply #208 on: June 07, 2009, 04:10:33 pm »
Quote from: 12345abc on June 07, 2009, 03:03:26 pm
is the brain not involved in reflex actions???

Feflex actions happen without the intervention of the brain!
Example-when pupil constricts on bright light
When u touch a hot plate.....u would remove ur hhands immediately without thinking!
It's a very fast response!
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Offline IGCSE hater!

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Re: Biolgy paper 1 help!
« Reply #209 on: June 07, 2009, 04:21:55 pm »
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