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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 345627 times)

Offline Dana

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3165 on: June 07, 2010, 07:07:53 pm »
Quote from: ~VIN1094~ on June 07, 2010, 07:05:25 pm
Basically "xylem conducts water", that's what it means ;)


ah yes makes sense :P thank youu!
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3166 on: June 07, 2010, 07:08:36 pm »
Quote from: 8T on June 07, 2010, 07:01:14 pm
True, true so sorry to be wasting your time :(

NO problem at all!  ;)
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Offline Dana

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3167 on: June 07, 2010, 07:09:54 pm »
Quote from: ~VIN1094~ on June 07, 2010, 07:05:25 pm
Basically "xylem conducts water", that's what it means ;)

Sodium ions, Potassium ion, nitrate salts, nitrites salts, Ca and Mg ions .. anything else? (all dissolved in water)

nope, thats plenty thanks so much.
you spend so much time helping out here i wonder when YOU actually get time to study and solve? :P
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3168 on: June 07, 2010, 07:11:07 pm »
Quote from: 8T on June 07, 2010, 07:06:25 pm
And these too if u ppl please?

D
B
B

want explanation?
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3169 on: June 07, 2010, 07:14:54 pm »
A woman is most fertile when she ovulates. I'll fetch you a pic.








^^ Should help :) (Right click> View image)
« Last Edit: June 07, 2010, 07:17:38 pm by ~VIN1094~ »
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3170 on: June 07, 2010, 07:16:47 pm »
Please can someone explain these doubts.
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"In helping others, we shall help ourselves, for whatever good we give out completes the circle and comes back to us."

Offline the_grim_reaper

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3171 on: June 07, 2010, 07:20:12 pm »
Quote from: aangel42 on June 07, 2010, 07:12:16 pm
Okay, this is really frustrating my textbook (Mary Jones) and study guide (Dave Hayward) DO NOT cover fertility in women in depth. I'm getting all the menstrual cycle questions/related questions wrong.
Someone please help with M/J 03 Q27 (attached) and why it's not D, because doesn't the egg take a couple days to pass down?
Also about the lining shedding and thickening and stuff, what are the days this happens? I think I asked before, and Vin said that ovulation happens around day 14?

lol the egg doesn't exactly last "a couple of days." It can only survive for about 24 hours after being released. And sperm can survive inside the female for about 2-3 days. So there's hardly a period of 4 days when fertilisation can occur. Thus it must be C (remember fertilisation should be around ovulation). Secondly, the time period for D is too large. Thirdly, the sperm don't really fertilize an ovum in uterus. They do it when the egg is moving down and is in the oviducts. Thus it must be C.

Do you have IGCSE Biology by DG Mackean?? (the book of that study guide?) it covers this aspect in a lot of detail...
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3172 on: June 07, 2010, 07:21:03 pm »
Quote from: aangel42 on June 07, 2010, 07:19:13 pm
Well the first is D...

Please can someone explain.  I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen.  Why respiration?
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Offline SNA

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3173 on: June 07, 2010, 07:21:15 pm »
Quote from: aangel42 on June 07, 2010, 07:12:16 pm
Okay, this is really frustrating my textbook (Mary Jones) and study guide (Dave Hayward) DO NOT cover fertility in women in depth. I'm getting all the menstrual cycle questions/related questions wrong.
Someone please help with M/J 03 Q27 (attached) and why it's not D, because doesn't the egg take a couple days to pass down?
Also about the lining shedding and thickening and stuff, what are the days this happens? I think I asked before, and Vin said that ovulation happens around day 14?
it is C as that when ovulation (release of an ovum ) occurs thus, the female is most fertile. for D, this is when the lining thicken, in preparation for implantation to occur if fertilisation takes place. if fertilisation does not happen, the thickening uterus wall will break down causing menstruation. hope this helps!^^
.
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Offline SNA

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3174 on: June 07, 2010, 07:22:44 pm »
Quote from: Ivo on June 07, 2010, 07:21:03 pm
Please can someone explain.  I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen.  Why respiration?
without presence of sunlight,(usually at night) plant respire ,releasing co2.
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3175 on: June 07, 2010, 07:24:51 pm »
Quote from: aangel42 on June 07, 2010, 07:19:13 pm
Well the first is D...

And the third is B?

Why B?  And the second is a bit weird.
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Offline aangel42

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3176 on: June 07, 2010, 07:24:58 pm »
Quote from: SNA on June 07, 2010, 07:22:44 pm
without presence of sunlight,(usually at night) plant respire ,releasing co2.

Correction: plants always respire!!!
It involves the same equation as for humans (aerobic respiration = oxygen in, CO2 out)
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3177 on: June 07, 2010, 07:26:26 pm »
Quote from: Ivo on June 07, 2010, 07:21:03 pm
Please can someone explain.  I thought photosynthesis (plant nutrition) absorbs carbon dioxide and gives off oxygen.  Why respiration?

Respiration uses O2 and gives off CO2, these.
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Offline ambitious94

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3178 on: June 07, 2010, 07:26:59 pm »
Heyy can anyone please help me out with June 09 Q 3)
How cum it's not B and it's D...doesnt the plant have just four stamen ..UGHHH... ???
I cant manage more than 37 :(
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Offline aangel42

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #3179 on: June 07, 2010, 07:27:50 pm »
Quote from: Ivo on June 07, 2010, 07:24:51 pm
Why B?  And the second is a bit weird.

Yeah, exactly, I don't get the second at all, to be quite honest.
Ok, so I think it's B, because well major clue, is that heating is only occurring at A and B, so it has to be either one. When conducting a starch test, you must first boil the leaf in water to kill it (= liquid A is water) and then in alcohol, to dissolve the green chlorophyll so that the black coloring from when you put the iodine doesn't interfere and mix the colors up.
Another huge clue is the presence of the test tube, ethanol is a flammable liquid, so even if you have no idea about the starch test stages, you can just narrow it down to A and B, and guess with B since a test tube is present, so there's a higher chance that would be the answer.
Can anyone confirm this? And answer the second one?
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