Author Topic: Biolgy paper 1 help!  (Read 29113 times)

Offline unknown

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Re: Biolgy paper 1 help!
« Reply #195 on: June 07, 2009, 09:18:22 am »
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

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???

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.

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!!!!!

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?

Offline goin4dakill

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Re: Biolgy paper 1 help!
« Reply #200 on: June 07, 2009, 10:43:00 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

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!

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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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?

Offline Kim

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Re: Biolgy paper 1 help!
« Reply #204 on: June 07, 2009, 11:23:06 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
After all is said and done, more is said than done.

By the time a man realizes that maybe his father was right, he usually has a son who thinks he’s wrong.

The early bird may get the worm, but the second mouse gets the cheese.

nid404

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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

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???

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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Offline AS girl

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Re: Biolgy paper 1 help!
« Reply #208 on: June 07, 2009, 04:10:33 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!
If i fall along the way pick me up and dust me off...and if i get too tired to make it..be my breath so i can walk!!

Offline IGCSE hater!

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